Author Topic: Dave's fault finding technique and other stuff.............  (Read 18477 times)

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Offline What_NZ

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Hi there,

I'm a long time watcher of Dave's video's and find most of the things he shows and talks about to be informative, for some strange reason I also enjoy mailbag too. I have no reason to doubt his credentials and life experiences, actually I'm a fellow atheist so I like the guy for that reason alone!
I didn't want to join the forum to be a basher and I hope this first post is not taken the wrong way. Dave is very good at what he does in other areas but fault finding has me thinking most of the time "WTF is he doing......" and the latest Soniq TV repair video was the proverbial straw!
I don't want to make this a rant so will just cut to what I taught Electronics Technicians for some 30 odd years as a Workshop Manager and Trainer for Panasonic.
Do not deviate from these important steps -

1/ Confirm the customers description of the fault, also confirm the correct functionality of overall operation
2/ Check visually the outside for anything unusual or signs of damage, physical damage, liquid ingress etc
3/ Open the unit and recheck customers description of the fault, also reconfirm the correct functionality of overall operation
4/ Start a complete visual inspection looking for anything unusual, charring, over heating, damaged components, corrosion, obvious dry joints

Next -

- Always be aware of jumping to conclusions and following garden paths, don't go too deep too quickly. Reassess every now and then, why and what I am doing.

There are a number of branches the next steps could follow depending on the fault but basically in no particular order -

- Check for intermittents, tap test, flexing the PCB either by hand (safety first of course) or an insulated object.
- Alternating between a can of Freeze and a Hair dryer can help to isolate temperature related faults. Also helpful are small gas powered hot air blowers for pin point heating, even the hot tip of a soldering iron can be useful (be careful it is grounded)

- If you need to start tracing a fault then start with Power supply, Oscillators, Resets
- Don't assume ground is contiguous throughout the whole unit. I have seen many a technician fooled by an open circuit/floating ground while testing another PCB from a common ground point. Shift the ground point to the Circuit/PCB you are testing or check the ground continuity.
- Never assume that just because you have voltage you don't have excessive ripple.
- Before replacing a fuse (of any type) ask yourself "why did it fail?" check the resistance of the circuit on the secondary side.
- Carefully unplug, check and reconnect all relevant connectors
- Never change the design of a circuit or 'band-aid" components. You are not the designer and the circuit worked fine before it failed so fix it properly.

Always be aware of your personal safety, and the safety of the customer. Even if you are repairing your Mum's TV you don't want to kill her or burn the house down due to your shoddy repair - know your limitations and seek professional help if needed.

Of course there are things I have forgotten to mention.

My final point is, you can fault find with just a Multimeter. It is the most useful piece of test equipment you will have, try and get yourself an old type Analogue Multimeter too. An oscilloscope is also helpful, it doesn't have to be a storage one as I still use my analogue scope of 20 years. I know Dave uses some of the equipment he has for educational value but honestly you don't need them, they are just "bling" and can confuse rather than clarify a problem.

If you read this Dave, keep up the good work. I do admire what you are doing.
« Last Edit: June 19, 2014, 02:07:54 am by What_NZ »
 

Offline Richard Crowley

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Re: Dave's fault finding technique and other stuff.............
« Reply #1 on: June 19, 2014, 02:17:00 am »
Hear! Hear! 
Maybe a proper series on the principles of (BrEnglish) fault-finding or (AmEnglish) troubleshooting would be a valuable thing to add to the schedule. It could be of benefit to both young players as well as old hands.  And even better if he could show how to do it without using $1000s worth of test equipment.
 

Offline JoeO

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Re: Dave's fault finding technique and other stuff.............
« Reply #2 on: June 19, 2014, 02:47:42 am »
Minor point What_NZ.

" ... the most useful piece of test equipment ..." is sitting on top of your shoulders.

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Today, only 26,000 remain.
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #3 on: June 19, 2014, 02:52:21 am »
Minor point What_NZ.

" ... the most useful piece of test equipment ..." is sitting on top of your shoulders.

Oh so true......

 

Offline edpalmer42

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Re: Dave's fault finding technique and other stuff.............
« Reply #4 on: June 19, 2014, 02:52:42 am »
Minor point What_NZ.

" ... the most useful piece of test equipment ..." is sitting on top of your shoulders.

I thought that was the least used piece of test equipment.

.......Been there.........Done that.......

Ed
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #5 on: June 19, 2014, 03:02:34 am »
Hear! Hear! 
Maybe a proper series on the principles of (BrEnglish) fault-finding or (AmEnglish) troubleshooting would be a valuable thing to add to the schedule. It could be of benefit to both young players as well as old hands.  And even better if he could show how to do it without using $1000s worth of test equipment.

Yes it would be good but judging Dave's previous repair video's he would need to get back to basic principles. In the 30 (and more) years of repairing just about every type of electronic consumer product Panasonic made, I have never needed to use a Thermal Imaging camera or an ESR meter.
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #6 on: June 19, 2014, 03:08:24 am »
Minor point What_NZ.

" ... the most useful piece of test equipment ..." is sitting on top of your shoulders.

I thought that was the least used piece of test equipment.

.......Been there.........Done that.......

Ed

Sometimes you would think that is also true. I had a Technician trust upon me for training that had been trained (from apprenticeship) by Philips, possibly one of the most illogical thinking tech's I have ever dealt with/(to) - hehe, yes I was a hard task master - lol
 

Online EEVblog

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Re: Dave's fault finding technique and other stuff.............
« Reply #7 on: June 19, 2014, 03:27:45 am »
Yes it would be good but judging Dave's previous repair video's he would need to get back to basic principles. In the 30 (and more) years of repairing just about every type of electronic consumer product Panasonic made, I have never needed to use a Thermal Imaging camera or an ESR meter.

The thermal imaging camera was just for kicks, because I could. I did not mean to imply this is what you should use.
And in-circuit ESR meters are incredibly popular in the TV/consumer repair industry.
 

Offline Mr Smiley

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Re: Dave's fault finding technique and other stuff.............
« Reply #8 on: June 19, 2014, 03:36:24 am »
I've always found Design Engineers to be really awful Repair Engineers. And Repair Engineers/Technicians exceptionally good at repairing and correcting bad designs.

 :)
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Online EEVblog

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Re: Dave's fault finding technique and other stuff.............
« Reply #9 on: June 19, 2014, 03:39:17 am »
1/ Confirm the customers description of the fault, also confirm the correct functionality of overall operation

I did.

Quote
2/ Check visually the outside for anything unusual or signs of damage, physical damage, liquid ingress etc

I did.

Quote
3/ Open the unit and recheck customers description of the fault, also reconfirm the correct functionality of overall operation

I did.

Quote
4/ Start a complete visual inspection looking for anything unusual, charring, over heating, damaged components, corrosion, obvious dry joints

I did. Dry joints are a bit hard without taking out the PSU board, so you do top side visuals first.

Quote
- Check for intermittents, tap test, flexing the PCB either by hand (safety first of course) or an insulated object.

I eventually got to that (and not as long into it as you think, things are done differently and slower because I'm shooting a video at the same time), but it was not my first step in this case because there was no indication that there was a mechanical aspect to this fault. It's not like my mum whacked the set and it came good etc.
The symptoms pointed toward an aging electrical fault. e.g. capacitors, marginal PSU or some such.
Any tech who repaired this TV without at least checking those caps (at least visually), then I would call them a bad tech.

Quote
- Alternating between a can of Freeze and a Hair dryer can help to isolate temperature related faults. Also helpful are small gas powered hot air blowers for pin point heating, even the hot tip of a soldering iron can be useful (be careful it is grounded)

I didn't get that far because the mechanical stress test was next in the list.

Quote
- Never assume that just because you have voltage you don't have excessive ripple.

That's why I used a scope.

Quote
- Before replacing a fuse (of any type) ask yourself "why did it fail?" check the resistance of the circuit on the secondary side.

I did. That was off camera, forgot to include it.

Quote
- Carefully unplug, check and reconnect all relevant connectors

Did that.

Quote
- Never change the design of a circuit or 'band-aid" components. You are not the designer and the circuit worked fine before it failed so fix it properly.

I didn't do that.

Quote
My final point is, you can fault find with just a Multimeter. It is the most useful piece of test equipment you will have, try and get yourself an old type Analogue Multimeter too. An oscilloscope is also helpful, it doesn't have to be a storage one as I still use my analogue scope of 20 years. I know Dave uses some of the equipment he has for educational value but honestly you don't need them, they are just "bling" and can confuse rather than clarify a problem.

Well, there's a shock, a multimeter and an oscilloscope are the two basic electronics troubleshooting tools, who would have thought!
I used both here of course.
A few people commented on the fact that I used an Agilent 3000X series scope for this. And of course that's just a pointless comment.

I honestly don't see how I did anything grossly wrong or out of place here?  :-//
The thermal camera was for kicks as I said.
I opened the case and checked the basics based on the symptoms I had to hand, and found and fixed the fault pretty quickly.
« Last Edit: June 19, 2014, 03:46:01 am by EEVblog »
 

Online EEVblog

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Re: Dave's fault finding technique and other stuff.............
« Reply #10 on: June 19, 2014, 03:43:41 am »
I've always found Design Engineers to be really awful Repair Engineers. And Repair Engineers/Technicians exceptionally good at repairing and correcting bad designs.

Well, yeah, of course. I haven't done professional general repair work since 1989/90, and have never repaired consumer items or TV's.
A professional TV tech probably could likely have told you the fault without even opening the case.
 

Offline sleemanj

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Re: Dave's fault finding technique and other stuff.............
« Reply #11 on: June 19, 2014, 03:45:16 am »
I have never needed to use a Thermal Imaging camera

30 years ago you wouldn't have had a hand held reasonably high resolution real time thermal imaging camera sitting on your desk.

Do we forsake new tools simply because "I never needed them before". 

Paper maps still work, so why do we have GPS?

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Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #12 on: June 19, 2014, 03:57:19 am »
I have never needed to use a Thermal Imaging camera

30 years ago you wouldn't have had a hand held reasonably high resolution real time thermal imaging camera sitting on your desk.

Do we forsake new tools simply because "I never needed them before". 

Paper maps still work, so why do we have GPS?

Yikes!   I never said "30 years ago" maybe read before you post. You obviously missed the whole point. Ever heard of the saying "just because you can, doesn't mean you need to."
 

Offline Mr Smiley

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Re: Dave's fault finding technique and other stuff.............
« Reply #13 on: June 19, 2014, 04:02:24 am »
I have never needed to use a Thermal Imaging camera

30 years ago you wouldn't have had a hand held reasonably high resolution real time thermal imaging camera sitting on your desk.

Do we forsake new tools simply because "I never needed them before". 

Paper maps still work, so why do we have GPS?

Yikes!   I never said "30 years ago" maybe read before you post. You obviously missed the whole point. Ever heard of the saying "just because you can, doesn't mean you need to."

Yes you did, reply #5 :-DD
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Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #14 on: June 19, 2014, 04:03:28 am »
Yes it would be good but judging Dave's previous repair video's he would need to get back to basic principles. In the 30 (and more) years of repairing just about every type of electronic consumer product Panasonic made, I have never needed to use a Thermal Imaging camera or an ESR meter.

The thermal imaging camera was just for kicks, because I could. I did not mean to imply this is what you should use.
And in-circuit ESR meters are incredibly popular in the TV/consumer repair industry.

Yes that's why I said in the first post
<SNIP>
I know Dave uses some of the equipment he has for educational value but honestly you don't need them, they are just "bling" and can confuse rather than clarify a problem. <SNIP>
Some workshops have ESR meters but good techs never need to use them, for instance we never had one at Panasonic.
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #15 on: June 19, 2014, 04:16:37 am »
I've always found Design Engineers to be really awful Repair Engineers. And Repair Engineers/Technicians exceptionally good at repairing and correcting bad designs.

<SNIP>
A professional TV tech probably could likely have told you the fault without even opening the case.

If he had it would have been a guess, you did the right thing by opening it up.
« Last Edit: June 19, 2014, 05:07:49 am by What_NZ »
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #16 on: June 19, 2014, 04:24:41 am »
<SNIP>
I honestly don't see how I did anything grossly wrong or out of place here?  :-//
The thermal camera was for kicks as I said.
I opened the case and checked the basics based on the symptoms I had to hand, and found and fixed the fault pretty quickly.

I am truly sorry if I have offended you, it was not my intention. The repair methodology was general and for everyone, it wasn't directed specifically at you or at that particular repair.
It was when you removed the caps to test with the ESR meter without checking voltages first and then the bodgy job with the connector at the end. It seemed like you ran out of time and said "Oh to hell with it" and the end repair was a big let down. Especially for a tech like me, I have never done that sort of thing in my life.
« Last Edit: June 19, 2014, 04:31:19 am by What_NZ »
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #17 on: June 19, 2014, 05:05:33 am »
I've always found Design Engineers to be really awful Repair Engineers. And Repair Engineers/Technicians exceptionally good at repairing and correcting bad designs.

 :)

Yes in general I would agree. Some designer's don't want to hear about their bad design but it is amazing how it gets corrected in a future revision. I worked with the team that designed the world's first Direct Drive electronically commutated washing machine. It was a great design but the lead designer had the communications lead from the control panel module coming down from the top of the machine and the motor harness going into a plug/socket on the top of the motor drive electronics module. I warned him that any moisture or condensation from a hot wash would collect on the wires and run down into the plug with obvious consequences. He didn't want to know about such a trivial thing and guess what happened after the product was eventually finalised and sold.... It only took a few months before we had trouble with corrosion in the connector. His solution was to make the wires longer so a drip 'U' could be put in and wrap some foam tape around the wires entering the plug.
 

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Re: Dave's fault finding technique and other stuff.............
« Reply #18 on: June 19, 2014, 05:19:14 am »
I am truly sorry if I have offended you, it was not my intention. The repair methodology was general and for everyone, it wasn't directed specifically at you or at that particular repair.
It was when you removed the caps to test with the ESR meter without checking voltages first

I was always going to test the capacitor ESR anyway, along with the voltages, so who cares which way around I measured them?
If that's your only complaint, then, well, nothing to see here.

BTW, there is a bit of "video production" involved here, I may not have necessarily done things the same way if I wasn't making a video.
I speculated on camera up-front that a likely culprit might be the capacitors, so it makes sense to check the capacitors visually and ESR first upon opening.

Quote
and then the bodgy job with the connector at the end. It seemed like you ran out of time and said "Oh to hell with it" and the end repair was a big let down.

I did run out of time. My mum wanted her TV back and I had an adequate fix, so that was that.
Those watching the live feed saw that. I literally fixed it and shot the last scene a minute before I headed out to pick up my mum.
What was I supposed to do, order a new TCON board and cable, and matching SMD fuse and wait a week or two before giving my mum her TV back and then uploading the perfect ending video?

Quote
Especially for a tech like me, I have never done that sort of thing in my life.

Because you are a professional repair tech being paid to fix things professionally for clients.
I am the complete opposite of that, fixing my mums TV in limited time for free. The result was adequate for the occasion IMO.
 

Online EEVblog

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Re: Dave's fault finding technique and other stuff.............
« Reply #19 on: June 19, 2014, 05:21:13 am »
If he had it would have been a guess, you did the right thing by opening it up.

Come on, any experienced person in this situation is going to have a guess up front.
If you, as professional repair tech claim you don't do that, then I'm going to call you liar  :P
 

Offline bitwelder

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Re: Dave's fault finding technique and other stuff.............
« Reply #20 on: June 19, 2014, 05:26:14 am »
Some workshops have ESR meters but good techs never need to use them, for instance we never had one at Panasonic.
I would hope that in a Panasonic product you don't have to hunt for shoddy one-hung-low capacitors  :o
 

Offline ludzinc

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Re: Dave's fault finding technique and other stuff.............
« Reply #21 on: June 19, 2014, 05:34:56 am »
I've always found Design Engineers to be really awful Repair Engineers. And Repair Engineers/Technicians exceptionally good at repairing and correcting bad designs.

 :)

Yes in general I would agree. Some designer's don't want to hear about their bad design but it is amazing how it gets corrected in a future revision. I worked with the team that designed the world's first Direct Drive electronically commutated washing machine. It was a great design but the lead designer had the communications lead from the control panel module coming down from the top of the machine and the motor harness going into a plug/socket on the top of the motor drive electronics module. I warned him that any moisture or condensation from a hot wash would collect on the wires and run down into the plug with obvious consequences. He didn't want to know about such a trivial thing and guess what happened after the product was eventually finalised and sold.... It only took a few months before we had trouble with corrosion in the connector. His solution was to make the wires longer so a drip 'U' could be put in and wrap some foam tape around the wires entering the plug.

God, I hate when people play the 'I told you so' card.

You believed there was a problem with the design, you had one conversation with a stubborn twit, and then let the company deal with the consequences?

If you were so sure of your convictions why did you not pursue this further?

Not a great team player there...

In my career I've done tech, design and now management, and I've learnt a lot from everyone at each phase.  But its surprising how hard it is to get people to COMMUNICATE with each other.  Blame belongs on both sides there.
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #22 on: June 19, 2014, 05:35:12 am »
Some workshops have ESR meters but good techs never need to use them, for instance we never had one at Panasonic.
I would hope that in a Panasonic product you don't have to hunt for shoddy one-hung-low capacitors  :o

See my other Thread https://www.eevblog.com/forum/reviews/repair-3com-basline-switch-model-2808/ about failed Nichicon capacitors in a 3com network switch. A quality product with quality caps. The brand doesn't matter the frequency of failure will so it can happen.
I hope you don't think Panasonic only use Panasonic Capacitors?
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #23 on: June 19, 2014, 05:42:18 am »
I've always found Design Engineers to be really awful Repair Engineers. And Repair Engineers/Technicians exceptionally good at repairing and correcting bad designs.

 :)

Yes in general I would agree. Some designer's don't want to hear about their bad design but it is amazing how it gets corrected in a future revision. I worked with the team that designed the world's first Direct Drive electronically commutated washing machine. It was a great design but the lead designer had the communications lead from the control panel module coming down from the top of the machine and the motor harness going into a plug/socket on the top of the motor drive electronics module. I warned him that any moisture or condensation from a hot wash would collect on the wires and run down into the plug with obvious consequences. He didn't want to know about such a trivial thing and guess what happened after the product was eventually finalised and sold.... It only took a few months before we had trouble with corrosion in the connector. His solution was to make the wires longer so a drip 'U' could be put in and wrap some foam tape around the wires entering the plug.

God, I hate when people play the 'I told you so' card.

You believed there was a problem with the design, you had one conversation with a stubborn twit, and then let the company deal with the consequences?

If you were so sure of your convictions why did you not pursue this further?

Not a great team player there...

In my career I've done tech, design and now management, and I've learnt a lot from everyone at each phase.  But its surprising how hard it is to get people to COMMUNICATE with each other.  Blame belongs on both sides there.

He was the lead designer, I was the junior maybe you never worked in a large company before or maybe you are just different. My concern was heard and documented, I was overridden by the man in charge. Yes, there is no 'I" in "Team" I didn't want to be the no "U" in team either. I am not going to loose my job just for the sake of pride.
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #24 on: June 19, 2014, 06:01:05 am »
If he had it would have been a guess, you did the right thing by opening it up.

Come on, any experienced person in this situation is going to have a guess up front.
If you, as professional repair tech claim you don't do that, then I'm going to call you liar  :P

Wow that's a bit strong. Really you're going to call me a liar?
Your are not in the repair industry and haven't been since 1989/90 but profess to know "A professional TV tech probably could likely have told you the fault without even opening the case." All I said is, "it would have been a guess" anyone can guess of course but that doesn't mean they "know" and if he had said "It is the caps" he would have been wrong, as you found.
 

Offline Towger

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Re: Dave's fault finding technique and other stuff.............
« Reply #25 on: June 19, 2014, 06:05:56 am »
Some workshops have ESR meters but good techs never need to use them, for instance we never had one at Panasonic.

A useful, fairly cheep item of kit, which has come into its own in recent years with the widespread use of cheap switchmode power supplies, with even cheaper Chinese capacitors. Of course not a problem Panasonic should have with their own brand high quality capacitor factories.
 

Offline Towger

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Re: Dave's fault finding technique and other stuff.............
« Reply #26 on: June 19, 2014, 06:17:31 am »
He was the lead designer, I was the junior maybe you never worked in a large company before or maybe you are just different.
Richard Dyson?
 

Online Rasz

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Re: Dave's fault finding technique and other stuff.............
« Reply #27 on: June 19, 2014, 06:25:00 am »
Some workshops have ESR meters but good techs never need to use them, for instance we never had one at Panasonic.

Thats because authorised repair centres deal mainly in warranty repairs = hardware that is less than 1-2, 3 at max years old. Panasonic using genuine Panasonic caps has to help too.
 Ordinary TV/Monitor/switching power supply/other consumer crap repair procedure starts with swapping all the mayor caps, often without even measuring them. This is precisely because of shitty caps being used for the last 10 years. Its faster (=cheaper) to swap 5 caps than to measure and ponder over them.

Wow that's a bit strong. Really you're going to call me a liar?
Your are not in the repair industry and haven't been since 1989/90 but profess to know "A professional TV tech probably could likely have told you the fault without even opening the case." All I said is, "it would have been a guess" anyone can guess of course but that doesn't mean they "know" and if he had said "It is the caps" he would have been wrong, as you found.

Yes, professional repairman can guess correctly from experience with high level of confidence just by symptoms alone. What exactly are you arguing about here? When I see dead Core2 laptop I dont even have to open it to guess its the Nvidia GPU (99% of cases). When I see Benq LCD that fails to start I already know its transistors in the inverter etc. There are plenty of typical faults for particular brands/type of equipment.
« Last Edit: June 19, 2014, 06:28:32 am by Rasz »
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Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #28 on: June 19, 2014, 06:27:19 am »
Some workshops have ESR meters but good techs never need to use them, for instance we never had one at Panasonic.

A useful, fairly cheep item of kit, which has come into its own in recent years with the widespread use of cheap switchmode power supplies, with even cheaper Chinese capacitors. Of course not a problem Panasonic should have with their own brand high quality capacitor factories.

Yikees this is getting harder.... Please don't assume that Panasonic uses only Panasonic Capacitors. Maybe Dave will get the chance to show that most major companies use many other brands of components too. What major companies do, which is probably different from smaller companies is mass testing of second sourced components, this insures somewhat their long term reliability.
I would say most cheap capacitors show visual signs of failure, bulging tops and/or leakage around the base. In circuit testing is not conclusive in all cases.
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #29 on: June 19, 2014, 06:32:19 am »
Some workshops have ESR meters but good techs never need to use them, for instance we never had one at Panasonic.

Thats because authorised repair centres deal mainly in warranty repairs = hardware that is less than 1-2, 3 at max years old. Panasonic using genuine Panasonic caps has to help too.
 Ordinary TV/Monitor/switching power supply/other consumer crap repair procedure starts with swapping all the mayor caps, often without even measuring them. This is precisely because of shitty caps being used for the last 10 years. Its faster (=cheaper) to swap 5 caps than to measure and ponder over them.

Wow that's a bit strong. Really you're going to call me a liar?
Your are not in the repair industry and haven't been since 1989/90 but profess to know "A professional TV tech probably could likely have told you the fault without even opening the case." All I said is, "it would have been a guess" anyone can guess of course but that doesn't mean they "know" and if he had said "It is the caps" he would have been wrong, as you found.

Yes, professional repairman can guess correctly from experience with high level of confidence just by symptoms alone. What exactly are you arguing about here? When I see dead Core2 laptop I dont even have to open it to guess its the Nvidia GPU (99% of cases). When I see Benq LCD that fails to start I already know its transistors in the inverter etc. There are plenty of typical faults for particular brands/type of equipment.

Appears to be the difference between "know" and "guess". Just like you said in your post "I dont even have to open it to guess its the Nvidia GPU (99% of cases)." so you guess but cannot be 100% certain. I really don't want to argue this point as it is really irrelevant. I'm not sure as to why he pounced on it.
 

Offline IanJ

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Re: Dave's fault finding technique and other stuff.............
« Reply #30 on: June 19, 2014, 06:49:34 am »
If he had it would have been a guess, you did the right thing by opening it up.

Come on, any experienced person in this situation is going to have a guess up front.
If you, as professional repair tech claim you don't do that, then I'm going to call you liar  :P

Wow that's a bit strong. Really you're going to call me a liar?
Your are not in the repair industry and haven't been since 1989/90 but profess to know "A professional TV tech probably could likely have told you the fault without even opening the case." All I said is, "it would have been a guess" anyone can guess of course but that doesn't mean they "know" and if he had said "It is the caps" he would have been wrong, as you found.

Not sure I understand the purpose of this thread now..........but all I can say is:-

EEVBlog = Electronics entertainment centred around Dave's many years of professional and non-professional experiences & knowledge. Look over his shoulder as he teaches us, shares with us & guesses with us.

With that in mind......ALL his videos are spot on.

Ian.
Ian Johnston
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Manufacturer of the PDVS2
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #31 on: June 19, 2014, 07:17:19 am »
If he had it would have been a guess, you did the right thing by opening it up.

Come on, any experienced person in this situation is going to have a guess up front.
If you, as professional repair tech claim you don't do that, then I'm going to call you liar  :P

Wow that's a bit strong. Really you're going to call me a liar?
Your are not in the repair industry and haven't been since 1989/90 but profess to know "A professional TV tech probably could likely have told you the fault without even opening the case." All I said is, "it would have been a guess" anyone can guess of course but that doesn't mean they "know" and if he had said "It is the caps" he would have been wrong, as you found.

Not sure I understand the purpose of this thread now..........but all I can say is:-

EEVBlog = Electronics entertainment centred around Dave's many years of professional and non-professional experiences & knowledge. Look over his shoulder as he teaches us, shares with us & guesses with us.

With that in mind......ALL his videos are spot on.

Ian.

Yes it went off track and I'm basically done with it.
Of course anyone is free to continue to pick it apart but for what it's worth I still stand by my first post and first post only.
The intention was to help others out there to follow a logical sequence for fault finding. I thought my 30 years of training Technicians in a major company would be helpful and was using some of Dave's not so logical methods as an example but apparently I failed.
For what it's worth - If I see questions that are on the subject of "fault finding help" and are not just fanboy jives, I will be happy to answer them.
« Last Edit: June 19, 2014, 07:19:09 am by What_NZ »
 

Offline Kjelt

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Re: Dave's fault finding technique and other stuff.............
« Reply #32 on: June 19, 2014, 07:36:32 am »
I think a lot of people forget that Dave is not only the main "actor" in the videos but simultaneously the cameraman and director.
This makes it much harder to be your normal self and show the same capabilities as if you had a discovery channel team filming and doing all the other work,
use multiple takes, etc.
One of the best examples of this is the solder paste demo video with the pcb's and stencil from free_electron's book.
I never ever saw such a worse demo of solderpaste application and use but he had to do three things at the same time.
I am sure that if he had the sole task doing it it would have been much better as others experienced doing it a couple of times.
Still I admire his balls for putting that video on the air, showing he is not infallible and still making his point.
What I do find good in criticism is if there are any safety risks, for instance the person saying an isolation transformer should be used and shown to be used in the video.
Repairing a life opened tv should have a lot of warnings for young ones not to do this if they are not experienced since it potentially could kill you.
At least the old tv's, unsure if the new ones have an isolated SMPS and it is perfectly safe.
Maybe a good idea to place a standard warning before this kind of videos Dave?
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #33 on: June 19, 2014, 08:03:04 am »
<SNIP>What I do find good in criticism is if there are any safety risks, for instance the person saying an isolation transformer should be used and shown to be used in the video.
Repairing a life opened tv should have a lot of warnings for young ones not to do this if they are not experienced since it potentially could kill you.
At least the old tv's, unsure if the new ones have an isolated SMPS and it is perfectly safe.
Maybe a good idea to place a standard warning before this kind of videos Dave?

Oh you are so right!
Repairing anything that is powered by the AC Mains voltage or generates high voltage internally should raise the safety flag as high as a kite! Often but not all manufactures will show on the PCB's warning symbols where there is high voltage or lethal voltages. No matter what the product, personal safety and the safety of the customer is the most important thing, life is way more precious than a $300 whatever product.
Always treat any so called safety product with respect, know how it works and what its limitations are, whether it be an ELCB (Earth Leakage Circuit Breaker), RCD (Residual Current Device) or Isolating transformer. Always assume something is "hot/live" then check whether it is or is not, before touching or connecting any grounded test equipment or any equipment that is Double Insulated but has an exposed metal chassis.
Actually it would be a great idea for a new EEVblog video.
« Last Edit: June 19, 2014, 10:19:32 am by What_NZ »
 

Offline vk6zgo

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Re: Dave's fault finding technique and other stuff.............
« Reply #34 on: June 19, 2014, 08:06:36 am »
Hi there,

I'm a long time watcher of Dave's video's and find most of the things he shows and talks about to be informative, for some strange reason I also enjoy mailbag too. I have no reason to doubt his credentials and life experiences, actually I'm a fellow atheist so I like the guy for that reason alone!
I didn't want to join the forum to be a basher and I hope this first post is not taken the wrong way. Dave is very good at what he does in other areas but fault finding has me thinking most of the time "WTF is he doing......" and the latest Soniq TV repair video was the proverbial straw!
I don't want to make this a rant so will just cut to what I taught Electronics Technicians for some 30 odd years as a Workshop Manager and Trainer for Panasonic.
Do not deviate from these important steps -

1/ Confirm the customers description of the fault, also confirm the correct functionality of overall operation
2/ Check visually the outside for anything unusual or signs of damage, physical damage, liquid ingress etc
3/ Open the unit and recheck customers description of the fault, also reconfirm the correct functionality of overall operation
4/ Start a complete visual inspection looking for anything unusual, charring, over heating, damaged components, corrosion, obvious dry joints

Next -

- Always be aware of jumping to conclusions and following garden paths, don't go too deep too quickly. Reassess every now and then, why and what I am doing.

There are a number of branches the next steps could follow depending on the fault but basically in no particular order -

- Check for intermittents, tap test, flexing the PCB either by hand (safety first of course) or an insulated object.
- Alternating between a can of Freeze and a Hair dryer can help to isolate temperature related faults. Also helpful are small gas powered hot air blowers for pin point heating, even the hot tip of a soldering iron can be useful (be careful it is grounded)

- If you need to start tracing a fault then start with Power supply, Oscillators, Resets
- Don't assume ground is contiguous throughout the whole unit. I have seen many a technician fooled by an open circuit/floating ground while testing another PCB from a common ground point. Shift the ground point to the Circuit/PCB you are testing or check the ground continuity.
- Never assume that just because you have voltage you don't have excessive ripple.
- Before replacing a fuse (of any type) ask yourself "why did it fail?" check the resistance of the circuit on the secondary side.
- Carefully unplug, check and reconnect all relevant connectors
- Never change the design of a circuit or 'band-aid" components. You are not the designer and the circuit worked fine before it failed so fix it properly.

Always be aware of your personal safety, and the safety of the customer. Even if you are repairing your Mum's TV you don't want to kill her or burn the house down due to your shoddy repair - know your limitations and seek professional help if needed.

Of course there are things I have forgotten to mention.

My final point is, you can fault find with just a Multimeter. It is the most useful piece of test equipment you will have, try and get yourself an old type Analogue Multimeter too. An oscilloscope is also helpful, it doesn't have to be a storage one as I still use my analogue scope of 20 years. I know Dave uses some of the equipment he has for educational value but honestly you don't need them, they are just "bling" and can confuse rather than clarify a problem.

If you read this Dave, keep up the good work. I do admire what you are doing.

Back in the day,I was,among other things,responsible for the repair,& availability of Picture Monitors at a TV Studio.

This also included some top end Domestic TV sets.

Management decided to outsource the repair of some of the big Sony 27" Domestics,as they thought things were getting on top of us a bit!

We attached a note to the first set saying what we had checked,hoping it would be useful to the Serviceman.
After a couple of weeks we got a call that it was fixed.

When I picked it up,I noticed their job sheet attached to it.

Under "nature of fault",it said "doesn't work"!

So much for:-
"1/ Confirm the customers description of the fault, also confirm the correct functionality of overall operation"

Ever"tigers for punishment",we sent another of these sets out to another Service company for a few problems.

We got a call:- "The tube is faulty!"

"OK",we said,& despatched a "regunned" tube to them,with strict instructions to return the old one intact so it could also be "regunned".

We got the tube back with the end knocked off,& the TV with the new tube "fitted",but not in any way converged,or any purity adjustments done.
We spent half a day finishing their job!
Luckily,the regunning place still managed to do the tube OK.

There was little talk about "outsourcing" from then on! ;D

With the "in-house " stuff,when Production folk wanted a certain number of Monitors,you needed to supply them--or else!
There was not any case where you could write off a unit as "beyond economical repair",so we went to fairly extreme lengths to keep them available & meeting Broadcast specs.

Due to time constraints,we quite often had to bend the words if not the spirit of  your injunction:-

"- Never change the design of a circuit or 'band-aid" components. You are not the designer and the circuit worked fine before it failed so fix it properly."


With some equipment,it didn't "work fine",so the same fault would recur-----for no other reason than the use of inadequate components in the original design.

Even with good designs,it was often necessary to fit different components because the original ones were unobtainable.
In every case,this led to a reliable & safe repair.


 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #35 on: June 19, 2014, 08:30:14 am »
<SNIP>

Back in the day,I was,among other things,responsible for the repair,& availability of Picture Monitors at a TV Studio.

This also included some top end Domestic TV sets.

Management decided to outsource the repair of some of the big Sony 27" Domestics,as they thought things were getting on top of us a bit!

We attached a note to the first set saying what we had checked,hoping it would be useful to the Serviceman.
After a couple of weeks we got a call that it was fixed.

When I picked it up,I noticed their job sheet attached to it.

Under "nature of fault",it said "doesn't work"!

So much for:-
"1/ Confirm the customers description of the fault, also confirm the correct functionality of overall operation"

Ever"tigers for punishment",we sent another of these sets out to another Service company for a few problems.

We got a call:- "The tube is faulty!"

"OK",we said,& despatched a "regunned" tube to them,with strict instructions to return the old one intact so it could also be "regunned".

We got the tube back with the end knocked off,& the TV with the new tube "fitted",but not in any way converged,or any purity adjustments done.
We spent half a day finishing their job!
Luckily,the regunning place still managed to do the tube OK.

There was little talk about "outsourcing" from then on! ;D

With the "in-house " stuff,when Production folk wanted a certain number of Monitors,you needed to supply them--or else!
There was not any case where you could write off a unit as "beyond economical repair",so we went to fairly extreme lengths to keep them available & meeting Broadcast specs.

Due to time constraints,we quite often had to bend the words if not the spirit of  your injunction:-

"- Never change the design of a circuit or 'band-aid" components. You are not the designer and the circuit worked fine before it failed so fix it properly."


With some equipment,it didn't "work fine",so the same fault would recur-----for no other reason than the use of inadequate components in the original design.

Even with good designs,it was often necessary to fit different components because the original ones were unobtainable.
In every case,this led to a reliable & safe repair.

Yes I can relate to everything you said and it's great to hear your experiences...
I always thought it was funny when the customers said "it doesn't work" then after plugging it in and it working. I would say "oh it is working" then they may say something like "oh yeah but the auto focus is not working." because they were customers you couldn't be upset with them but when a service company did the same thing time and time again, I was on the phone to their manager.
I was also involved with regunning of picture tubes in the early day, personally I never liked it and always gave the customer the choice of new or regun and explained why there was such a price difference. Interesting what you say as our regunning would not regun a tube that had been "cracked", the risk of oxidisation was just too high.
I always asked the service centres to contact us before modifying as there may be an official ECN (Engineering Change Notice), especially for common faults. If it was something we didn't know about, we replaced the unit and investigated it ourselves, with the help and final decision of the Japanese design engineers.
The service industry is surly an interesting one.
« Last Edit: June 19, 2014, 08:40:55 am by What_NZ »
 

Offline all_repair

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Re: Dave's fault finding technique and other stuff.............
« Reply #36 on: June 19, 2014, 09:19:03 am »
So far I read about those that criticised Dave technique but when come to sharing theirs were nothing but an illustration of factory workman checklist that already knew the problem from the database nd fixes that need to be painted. 

It is nothing wrong to go through the ESR of the capacitors especially when they need to be checked anyway.

My technique is:  See See See See See See Think Think Think See See See Think Think See See Think and then "do".  It is a sin to me that Dave did not use his numerous powerful inspection microscopes at all.
« Last Edit: June 19, 2014, 09:53:49 am by all_repair »
 

Offline HackedFridgeMagnet

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Re: Dave's fault finding technique and other stuff.............
« Reply #37 on: June 19, 2014, 09:43:41 am »
Quote
Always treat any so called safety product with respect, know how it works and what its limitations are, whether it be an ELCB (Earth Leakage Circuit Breaker) or Isolating transformer. Always assume something is "hot/live" then check whether it is or is not, before touching or connecting any grounded test equipment or any equipment that is Double Insulated but has an exposed metal chassis.

I've got to admit I don't treat ELCBs with much respect, nobody installs them in switchboards anymore as the Aus/NZ rules mandate RCDs and have done for maybe 20 years.

How do you check something is "hot/live" or not? Just interested in a service technicians point of view on this one.

 

Offline gildasd

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Re: Dave's fault finding technique and other stuff.............
« Reply #38 on: June 19, 2014, 09:51:10 am »
Just a note on FLIR;

My university (HZS Antwerp) competes in solar boat challenges:
http://www.solar1races.com/
http://www.dongenergysolarchallenge.com/

And we have a FLIR that was bought to test IC engine radiators (for a thesis project I think).
It did not take long for the solar racing team to grab the FLIR to check the battery pack (more than a 100 LI-Ion modules) in about a second during pit stops.

Bad cells show up as much hotter or cooler, are quickly isolated for testing and/or replacement in the evening.

A meter would suffice if we were using a lead acid battery.

Or a hand on the forehead if using oars.
« Last Edit: June 19, 2014, 09:56:12 am by gildasd »
I'm electronically illiterate
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #39 on: June 19, 2014, 10:06:13 am »
Quote
Always treat any so called safety product with respect, know how it works and what its limitations are, whether it be an ELCB (Earth Leakage Circuit Breaker) or Isolating transformer. Always assume something is "hot/live" then check whether it is or is not, before touching or connecting any grounded test equipment or any equipment that is Double Insulated but has an exposed metal chassis.

I've got to admit I don't treat ELCBs with much respect, nobody installs them in switchboards anymore as the Aus/NZ rules mandate RCDs and have done for maybe 20 years.

How do you check something is "hot/live" or not? Just interested in a service technicians point of view on this one.

Good point!
One of the biggest limitations with ELCB's or RCD's is they won't necessarily trip if the leakage to earth is too low or if you are directly across the mains as there may not be enough leakage to earth.
Check "hot/live" with respect to ground/earth. Usually the earth of a mains socket is sufficient. It worthwhile checking for both DC and AC voltages.
« Last Edit: June 19, 2014, 10:17:47 am by What_NZ »
 

Online EEVblog

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Re: Dave's fault finding technique and other stuff.............
« Reply #40 on: June 19, 2014, 10:22:59 am »
Wow that's a bit strong. Really you're going to call me a liar?

Relax, I was kidding, and trying to point out that you or anyone else would also have a guess at the fault before opening the case, just like I did. That's the nature of experienced technical people.
My problem is I do it on camera, warts and all for the entire world to see, and hence cop it every time I get anything even slightly wrong, or in this case, supposedly in the wrong order  ::)
 

Offline HackedFridgeMagnet

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Re: Dave's fault finding technique and other stuff.............
« Reply #41 on: June 19, 2014, 10:36:48 am »
Quote
Check "hot/live" with respect to ground/earth. Usually the earth of a mains socket is sufficient. It worthwhile checking for both DC and AC voltages.

My point here is that "hot" is slang for active and sometimes people use this term synonymously with "live".

But in the wiring rules AS/NZ 3000 the neutral is considered "live". I guess this is the case for mains rated equipment.

Anyway the only way to check that the chassis is not live is to pull the plug out of the wall and measure the insulation between the Chassis and both the Neutral and Live conductors.
Measuring the voltage doesn't check this.

 

Online EEVblog

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Re: Dave's fault finding technique and other stuff.............
« Reply #42 on: June 19, 2014, 10:45:32 am »
Still I admire his balls for putting that video on the air, showing he is not infallible and still making his point.

I don't see any "balls" in releasing this at all.
I made a (very reasonable) guess at the fault based on the symptoms, and I said that's what I'd check first and that's what I did.
It didn't turn out to be the problem, but so what? All I said was it was likely.

People have to remember that all up this is probably about 10 minutes worth of actual troubleshooting before I found the problem and few minutes more fixing it. I probably spent more time undoing screws and clearing the bench than finding the problem.  So I see this as nothing but an excellent result.
The videos are longer because that's the nature of the beast.
And if all I got was one person complaining I measured the caps first instead of the voltages, and one person complaining I used a 3000X scope to measure basic ripple, then I see this as a very successful video.
 

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Re: Dave's fault finding technique and other stuff.............
« Reply #43 on: June 19, 2014, 10:50:34 am »
intention was to help others out there to follow a logical sequence for fault finding. I thought my 30 years of training Technicians in a major company would be helpful and was using some of Dave's not so logical methods as an example but apparently I failed.

Please explain how my guessing that it might be the capacitors based on symptoms, and then checking said capacitors (that should be checked anyway), then moving onto the voltages, and then mechanical stuff before the fault was found in maybe 10 minutes, was in any way illogical?
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #44 on: June 19, 2014, 11:35:43 am »
Quote
Check "hot/live" with respect to ground/earth. Usually the earth of a mains socket is sufficient. It worthwhile checking for both DC and AC voltages.

My point here is that "hot" is slang for active and sometimes people use this term synonymously with "live".

But in the wiring rules AS/NZ 3000 the neutral is considered "live". I guess this is the case for mains rated equipment.

Anyway the only way to check that the chassis is not live is to pull the plug out of the wall and measure the insulation between the Chassis and both the Neutral and Live conductors.
Measuring the voltage doesn't check this.
IMO it is common in the Service industry to just say hot or live chassis (it doesn't mean Phase or Neutral) it may not be Electrical standards talk but you would instantly know what they meant by it.
Hmmm. Insulation would certainly test this for some situations but would fail for a chassis sitting at rectified mains voltage. I think I would feel safer measuring the AC and DC voltage. Well that is what is going to knock me for a six if I get it wrong.
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #45 on: June 19, 2014, 11:44:19 am »
Still I admire his balls for putting that video on the air, showing he is not infallible and still making his point.

I don't see any "balls" in releasing this at all.
I made a (very reasonable) guess at the fault based on the symptoms, and I said that's what I'd check first and that's what I did.
It didn't turn out to be the problem, but so what? All I said was it was likely.


People have to remember that all up this is probably about 10 minutes worth of actual troubleshooting before I found the problem and few minutes more fixing it. I probably spent more time undoing screws and clearing the bench than finding the problem.  So I see this as nothing but an excellent result.
The videos are longer because that's the nature of the beast.
And if all I got was one person complaining I measured the caps first instead of the voltages, and one person complaining I used a 3000X scope to measure basic ripple, then I see this as a very successful video.

Dave, Dave, Dave by all means have a go at me but please re-read Kjelts post again, he wasn't talking about the TV repair video. He was being oh so sympathetic towards you.....
 

Offline vk6zgo

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Re: Dave's fault finding technique and other stuff.............
« Reply #46 on: June 19, 2014, 12:08:24 pm »
<SNIP>

Back in the day,I was,among other things,responsible for the repair,& availability of Picture Monitors at a TV Studio.

This also included some top end Domestic TV sets.

Management decided to outsource the repair of some of the big Sony 27" Domestics,as they thought things were getting on top of us a bit!

We attached a note to the first set saying what we had checked,hoping it would be useful to the Serviceman.
After a couple of weeks we got a call that it was fixed.

When I picked it up,I noticed their job sheet attached to it.

Under "nature of fault",it said "doesn't work"!

So much for:-
"1/ Confirm the customers description of the fault, also confirm the correct functionality of overall operation"

Ever"tigers for punishment",we sent another of these sets out to another Service company for a few problems.

We got a call:- "The tube is faulty!"

"OK",we said,& despatched a "regunned" tube to them,with strict instructions to return the old one intact so it could also be "regunned".

We got the tube back with the end knocked off,& the TV with the new tube "fitted",but not in any way converged,or any purity adjustments done.
We spent half a day finishing their job!
Luckily,the regunning place still managed to do the tube OK.

There was little talk about "outsourcing" from then on! ;D

With the "in-house " stuff,when Production folk wanted a certain number of Monitors,you needed to supply them--or else!
There was not any case where you could write off a unit as "beyond economical repair",so we went to fairly extreme lengths to keep them available & meeting Broadcast specs.

Due to time constraints,we quite often had to bend the words if not the spirit of  your injunction:-

"- Never change the design of a circuit or 'band-aid" components. You are not the designer and the circuit worked fine before it failed so fix it properly."


With some equipment,it didn't "work fine",so the same fault would recur-----for no other reason than the use of inadequate components in the original design.

Even with good designs,it was often necessary to fit different components because the original ones were unobtainable.
In every case,this led to a reliable & safe repair.

Yes I can relate to everything you said and it's great to hear your experiences...
I always thought it was funny when the customers said "it doesn't work" then after plugging it in and it working. I would say "oh it is working" then they may say something like "oh yeah but the auto focus is not working." because they were customers you couldn't be upset with them but when a service company did the same thing time and time again, I was on the phone to their manager.
I was also involved with regunning of picture tubes in the early day, personally I never liked it and always gave the customer the choice of new or regun and explained why there was such a price difference. Interesting what you say as our regunning would not regun a tube that had been "cracked", the risk of oxidisation was just too high.
I always asked the service centres to contact us before modifying as there may be an official ECN (Engineering Change Notice), especially for common faults. If it was something we didn't know about, we replaced the unit and investigated it ourselves, with the help and final decision of the Japanese design engineers.
The service industry is surly an interesting one.

As I pointed out,we never had a lot of time to play with,& being a long way from the manufacturers,there was little opportunity to talk to them.
Sony were very good when it came to getting parts,but even with them,we often had to use alternative Semiconductors from other sources.
They also sent the mod updates regularly,which was pretty rare with  the other suppliers.

Wellview in Perth WA did an excellent job with reguns,especially with the Broadcast standard tubes used in Sony Studio Monitors.

Normally we only replaced the tubes in these with new,but when there was a "financial squeeze" on,we used the reguns in this equipment,too.
They met all Broadcast standards,so we continued to use them until we could return to the original rule.

Wellview normally did not regun "cracked" tubes,but as we were good customers,he agreed to try in the case referred to in my last posting,with good results.
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #47 on: June 19, 2014, 12:31:36 pm »
<SNIP>
As I pointed out,we never had a lot of time to play with,& being a long way from the manufacturers,there was little opportunity to talk to them.
Sony were very good when it came to getting parts,but even with them,we often had to use alternative Semiconductors from other sources.
They also sent the mod updates regularly,which was pretty rare with  the other suppliers.

Wellview in Perth WA did an excellent job with reguns,especially with the Broadcast standard tubes used in Sony Studio Monitors.

Normally we only replaced the tubes in these with new,but when there was a "financial squeeze" on,we used the reguns in this equipment,too.
They met all Broadcast standards,so we continued to use them until we could return to the original rule.

Wellview normally did not regun "cracked" tubes,but as we were good customers,he agreed to try in the case referred to in my last posting,with good results.

Distances in NZ are not so great so I was probably tougher on our service centres. Over the years I became good friends with some of the people at Panasonic Australia the guy responsible for Perth and WA told me how he would drive about 12 hours, nearly half way to Broome and the guys from Broome would drive down to meet him at a Hotel so he could run a training course for them. This was all because Panasonic wouldn't pay for him to fly to Broome but driving long distances and getting paid for it was ok. Just seemed so strange to me........
I always wondered if the regunning plant regunned the "cracked" tubes anyway and sold them for a nice profit.
 

Offline Strada916

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Re: Dave's fault finding technique and other stuff.............
« Reply #48 on: June 19, 2014, 02:08:59 pm »
The way I see it. Someone thinks Dave did not go about HIS repair the way someone else would have. If you do not like it don't watch it. I enjoy these types of videos as it shows how HE went about it.

I guess my point is everyone is different, everyone tackles the same job differently. The fact that Dave made a video of it, is to entertain his audience. Not everyone is going to like what he does. If you do not like it then do not watch it. There are plenty of others who enjoyed it.
just my 2 cents worth.
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Offline nitro2k01

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Re: Dave's fault finding technique and other stuff.............
« Reply #49 on: June 19, 2014, 03:22:06 pm »
- Before replacing a fuse (of any type) ask yourself "why did it fail?" check the resistance of the circuit on the secondary side.
This was the only point in that rant that stood out to me as something he had forgotten to do while I was watching the video. Though as he mentioned earlier, he did check that off-camera.
Whoa! How the hell did Dave know that Bob is my uncle? Amazing!
 

Offline Bored@Work

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Re: Dave's fault finding technique and other stuff.............
« Reply #50 on: June 19, 2014, 03:25:26 pm »
It is relatively simple. Someone is talking bull. I haven't seen a classic TV or audio equipment repair shop in the past (when stuff was still repaired) where they didn't have e.g. a transistor substitution book. Part substitutions were done regularly - with or without the help of a substitution list. And not only electronic parts, but also mechanical parts.

So much for
- Never change the design of a circuit or 'band-aid" components.
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Offline crispus

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Re: Dave's fault finding technique and other stuff.............
« Reply #51 on: June 19, 2014, 06:21:52 pm »
Why the video is private?
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Offline FireBird

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Re: Dave's fault finding technique and other stuff.............
« Reply #52 on: June 19, 2014, 07:21:01 pm »
I have no problem to access this video. Or are you talking about #632? It had to be temporarily removed because the video had a flaw.

 

Offline DJ

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Re: Dave's fault finding technique and other stuff.............
« Reply #53 on: June 19, 2014, 07:50:59 pm »
It is relatively simple. Someone is talking bull. I haven't seen a classic TV or audio equipment repair shop in the past (when stuff was still repaired) where they didn't have e.g. a transistor substitution book. Part substitutions were done regularly - with or without the help of a substitution list. And not only electronic parts, but also mechanical parts.

So much for
- Never change the design of a circuit or 'band-aid" components.

For the repair persons perspective,  not substituting / changing is generally good advice.

When I design something,  I may be going through all sorts of worst-case,  derating or other analyses that lead to the specification of a certain part (or alternatives as I will put in each component specification sheet, which is internal only). Changing a part may work short term, but may also lead to unintended consequences.  In general,  better parts are usually ok, as long as one understands what specs are important.  It may be more than value/Tolerance/power/voltage, etc.

On the other hand,  designers and often parts sourcing make mistakes. Sometimes a different part will work better. It is incumbent on the person doing the work to clearly understand a circuit before taking that step.

I will say from a designer's perspective,  that I love to have techs, users and other engineers tear my stuff apart. Much better in the long run for quality product.

 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #54 on: June 19, 2014, 09:02:05 pm »
It is relatively simple. Someone is talking bull. I haven't seen a classic TV or audio equipment repair shop in the past (when stuff was still repaired) where they didn't have e.g. a transistor substitution book. Part substitutions were done regularly - with or without the help of a substitution list. And not only electronic parts, but also mechanical parts.

So much for
- Never change the design of a circuit or 'band-aid" components.

This would have made a better question than a statement.
Transistor substitution is not considered as changing the design (generally). Even companies like Panasonic published such books, many Sanyo Service Manuals actually listed the substitutions in the parts list for the technician. What is important, is the ability of the technician to understand the design of the circuit. For general purpose transistors there is usually no harm in substituting and the designer will have just selected one of many possibilities, probably based on his past familiarity with its specification, cost, availability etc so generally no harm there...... However it is a different story when the transistor has been selected for a critical reason i.e. its specification is why the circuit operates or will continue to operate correctly. Replacing with a substitute part can be a trap that leads you around in circles.
Are you an Electronics Technician in the service industry? because I would have thought you would have encountered a situation already, where substituting a transistor (even from a book) failed to work correctly in the circuit you were repairing. Hence my advise to "Never change the design of a circuit or 'band-aid" components. As you are not the designer........."
« Last Edit: June 19, 2014, 09:22:39 pm by What_NZ »
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #55 on: June 19, 2014, 09:18:48 pm »
It is relatively simple. Someone is talking bull. I haven't seen a classic TV or audio equipment repair shop in the past (when stuff was still repaired) where they didn't have e.g. a transistor substitution book. Part substitutions were done regularly - with or without the help of a substitution list. And not only electronic parts, but also mechanical parts.

So much for
- Never change the design of a circuit or 'band-aid" components.

For the repair persons perspective,  not substituting / changing is generally good advice.

When I design something,  I may be going through all sorts of worst-case,  derating or other analyses that lead to the specification of a certain part (or alternatives as I will put in each component specification sheet, which is internal only). Changing a part may work short term, but may also lead to unintended consequences.  In general,  better parts are usually ok, as long as one understands what specs are important.  It may be more than value/Tolerance/power/voltage, etc.

On the other hand,  designers and often parts sourcing make mistakes. Sometimes a different part will work better. It is incumbent on the person doing the work to clearly understand a circuit before taking that step.

I will say from a designer's perspective,  that I love to have techs, users and other engineers tear my stuff apart. Much better in the long run for quality product.
Thanks and I would say you said it better than me.
Yes, I have seen huge cock-ups in production where parts sourcing substituted a part. Problems with testing had the design engineer  stomping through the testing area mumbling "Why the f__k do they employ me, when they know it all." the rework alone was 10's of thousands just because of one transistor but unfortunately it was used in multiple places.
In general I found design engineers extremely interesting people to talk with, there was always something to learn about why they designed a circuit this way or that. Can be amusing when you see an experienced engineer and one freshly out of university looking over a circuit, the young guy all cocky with new knowledge and the experienced engineer saying "they may teach you to do it like that, but in the real world ........."
« Last Edit: June 19, 2014, 09:28:16 pm by What_NZ »
 

Offline Bored@Work

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Re: Dave's fault finding technique and other stuff.............
« Reply #56 on: June 19, 2014, 10:11:20 pm »
In a repair shop it didn't matter what a designer wanted or desired. You were never going to meet that guy, and you gave a fart about who that guy was. And frankly, the designer was surly giving a fart about any repair technician and had moved on to many other projects.

What matters was the customer breathing down your neck. You found a defect transistor, you didn't stock it? So you turned to the substitution list and were happy if you had one of the suggested substitutions in stock. In it went. Fault was fixed. Customer happy. Customer paying.

That was the reality in every such shop I happened to know. So don't give me this repair technician trainer bull. You know nothing about the reality in a repair shop. So your lecture attempts here are a joke.
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Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #57 on: June 19, 2014, 11:24:38 pm »
In a repair shop it didn't matter what a designer wanted or desired. You were never going to meet that guy, and you gave a fart about who that guy was. And frankly, the designer was surly giving a fart about any repair technician and had moved on to many other projects.

What matters was the customer breathing down your neck. You found a defect transistor, you didn't stock it? So you turned to the substitution list and were happy if you had one of the suggested substitutions in stock. In it went. Fault was fixed. Customer happy. Customer paying.

That was the reality in every such shop I happened to know. So don't give me this repair technician trainer bull. You know nothing about the reality in a repair shop. So your lecture attempts here are a joke.
Wow so protective. So what did I say wrong? I didn't disagree with you. I just expanded as to why it may or may not be a good idea to substitute parts, Transistors was the example.
You have your experiences/knowledge of a repair shop and I have mine of the industry. I am not going to say you don't know what you are talking about so please don't say that of me either. I am trying to make this general information for the home hobbyist or amateur repairer. Of course it may not fit the experience of a tech working in a shop somewhere.
 

Offline onlooker

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Re: Dave's fault finding technique and other stuff.............
« Reply #58 on: June 20, 2014, 01:28:07 am »
Like many others felt, the video was entertaining for me. I never expected everything to be perfect with such a one person crew.

The only point made me nerves to watch was that Dave leaned the LCD screen on a corner of one of his test gears while pressing and tapping on the other side. I think maybe it is better to re-attach the TV stand after taking off the back cover. Anyway, that was what I did when I did my own repair of my 46" LCD TV recently (spanning 6 months, on and off).
 

Online EEVblog

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Re: Dave's fault finding technique and other stuff.............
« Reply #59 on: June 20, 2014, 02:08:43 am »
I think maybe it is better to re-attach the TV stand after taking off the back cover.

You can't with this model, I tried. It screws into the back cover.
 

Offline vk6zgo

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Re: Dave's fault finding technique and other stuff.............
« Reply #60 on: June 20, 2014, 05:48:24 am »
I found that the substitution lists were not always very helpful,as they often had typos & other errors.
Another thing was,depending on their origin,they often had little or no coverage of the other naming conventions (JEDEC-v- the rest).

I tended to look at what other manufacturers used in similar circuits.
For instance,if Philips used a particular Horizontal output transistor in a very similar circuit to the one Sony used,there was a pretty good possibility it would work OK in the Sony circuit.

Fixing Monitors,TVs,etc is not my main line of work,as I was mainly a Transmitter Tech.
That is an occupation with a broad streak of "bush mechanic",as you are always "under the hammer" to restore services.

With my earlier Employer,Telecom Aust,we had the contract to operate, maintain & repair the ABC Transmitters,as well as those of a major regional Commercial TV Network.

In one site,this company had a Thomson-CSF TV Transmitter.
The power supply for the Transistor PA's (TRPAs in NEC jargon) "let the smoke out" in a big way,so they had to go down in power to the 1kW LGT standby.

New parts from France?---Several weeks at the least!

It just happened that a similar supply for the TRPAs of an ABC NEC Tx was sitting as an extra spare at the Bickley site.
The guys from the other site grabbed it,(with permission),tweaked the voltage settings to match the Thomson,sat it outside the Tx ,as it wouldn't fit inside,wired it up (with due care as to safety).
They fired up the Thomson,& up it came,full power back---all good!

That power supply sat there for months before the parts arrived for the original one!
 

Offline What_NZ

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Re: Dave's fault finding technique and other stuff.............
« Reply #61 on: June 20, 2014, 06:47:20 am »
I found that the substitution lists were not always very helpful,as they often had typos & other errors.
Another thing was,depending on their origin,they often had little or no coverage of the other naming conventions (JEDEC-v- the rest).

I tended to look at what other manufacturers used in similar circuits.
For instance,if Philips used a particular Horizontal output transistor in a very similar circuit to the one Sony used,there was a pretty good possibility it would work OK in the Sony circuit.

Fixing Monitors,TVs,etc is not my main line of work,as I was mainly a Transmitter Tech.
That is an occupation with a broad streak of "bush mechanic",as you are always "under the hammer" to restore services.

With my earlier Employer,Telecom Aust,we had the contract to operate, maintain & repair the ABC Transmitters,as well as those of a major regional Commercial TV Network.

In one site,this company had a Thomson-CSF TV Transmitter.
The power supply for the Transistor PA's (TRPAs in NEC jargon) "let the smoke out" in a big way,so they had to go down in power to the 1kW LGT standby.

New parts from France?---Several weeks at the least!

It just happened that a similar supply for the TRPAs of an ABC NEC Tx was sitting as an extra spare at the Bickley site.
The guys from the other site grabbed it,(with permission),tweaked the voltage settings to match the Thomson,sat it outside the Tx ,as it wouldn't fit inside,wired it up (with due care as to safety).
They fired up the Thomson,& up it came,full power back---all good!

That power supply sat there for months before the parts arrived for the original one!

RF equipment was not really my area of expertise, actually to be honest I was always a bit scared of it, well the TX part of it anyway. Panasonic sold at various times some Marine Radio's. I can't remember exactly why but they had an unusually high number of dry joints so we saw quite a few of them, got my second RF burn from the output of one of them and it hurt like a bugger for weeks. The equipment I worked on was a toy compared to what you were servicing also a different set of skills and safety concerns to work on high powered RF equipment.
So thanks for sharing. I always like hearing about servicing in areas I was never involved with. Just shows how diverse the industry is.
« Last Edit: June 20, 2014, 07:59:04 am by What_NZ »
 

Offline gildasd

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Re: Dave's fault finding technique and other stuff.............
« Reply #62 on: June 20, 2014, 07:00:09 am »
Everybody has their own approved technique.

"Licks finger, sticks it in plugged TV set while humming to himself"

If the humming stops, the voltage drops.
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Offline Joule Thief

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Re: Dave's fault finding technique and other stuff.............
« Reply #63 on: June 20, 2014, 08:39:20 am »
Said it before and I'll say it again,

I come for the entertainment and I stay for the - well - the aftermath and diversity of opinions - yeah, that's the ticket !   :-DD
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Offline AlphZeta

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Re: Dave's fault finding technique and other stuff.............
« Reply #64 on: June 20, 2014, 10:55:32 pm »
One thing I like about EEVblog forrum is these often heated debates!

To Dave's defense, he has to make the video interesting enough to get his audience energized and engaged. Don't forget, this is his full time job :). I am sure he could easily have done a lot of his videos with just some very basic equipment, but then we would have missed all the fun!

Most of the time he uses those high-end and expensive equipment just because he has them (as he said, for kicks). Yes, for most repairs, a good analog multimeter, a half-decent digital multimeter and a scope will do the trick. I myself tend to be on the other side of the spectrum, using only the simplest tools I have but I am sure if I have those high end equipment, I'd use them just for fun as well.
 

Offline HighVoltage

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Re: Dave's fault finding technique and other stuff.............
« Reply #65 on: June 22, 2014, 09:03:27 am »
I have learned something from every repair video that Dave has done.
What more can I ask for?

Everyone of us has different ways to go about finding a problem.
Dave has one more challenge: He has to make it entertaining.
Imagine Dave would find the fault in 30 sec.... the video would be boring and over.


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Offline george graves

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Re: Dave's fault finding technique and other stuff.............
« Reply #66 on: June 22, 2014, 10:49:42 am »
I have learned something from every repair video that Dave has done.
What more can I ask for?

Same here.  I learned a lot to on that TV repair.  It wasn't my favorite video - but it was worth putting on in the background while I assessabled a small batch of stuff.

PS - somewhere these is a Dave "rant" on a walk (drive? - think it was a walk in a park or soemthing) that Dave gave about how he's "Not a bloody TV repair man!!!!"

Anyone have a link to that?  That would be funny about now!  Love ya Dave!


Online EEVblog

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Re: Dave's fault finding technique and other stuff.............
« Reply #67 on: June 22, 2014, 11:02:02 am »
Dave has one more challenge: He has to make it entertaining.
Imagine Dave would find the fault in 30 sec.... the video would be boring and over.

Well, that's the trick, which is why I'll throw out a speculator at the start to make it interesting rather than just say "I have absolutely no idea" lest I look a fool, likely involving common issues in repairs, such as the capacitors in this example which followed the symptoms.
So that means I go inside and check those caps I just mentioned straight away in order to keep the continuity there.

This was essentially 10 minutes tops of actual troubleshooting for I found the fault, so it's hardly dicking around not finding anything, it was a very quick and efficient repair. But the problem comes in when you try and shoot a video about it in "real time", and you end up with a much longer video. And in this case, a split video because that extra time setting up filming the first part of the video meant I ran out of time and had to go home. So it turned into a two parter.
 

Offline Kjelt

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Re: Dave's fault finding technique and other stuff.............
« Reply #68 on: June 22, 2014, 02:23:29 pm »
Still I admire his balls for putting that video on the air, showing he is not infallible and still making his point.
I don't see any "balls" in releasing this at all.
I was referring to a previous video where you were demoing solderpaste and stencilling technique from free_electrons book not this video ;)
 


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