Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 1804619 times)

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Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32675 on: June 06, 2019, 06:50:49 am »
@med good work, I agree, leaving the wiring as is otherwise it a virtual complete rebuild and nobody would any wiser by you doing it. What is the normal B+ voltage when loaded then? I like to have the caps rated at 50% higher otherwise their lifespan could be quite short and a transient take them out [emoji849]

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Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32676 on: June 06, 2019, 07:26:51 am »
@med good work, I agree, leaving the wiring as is otherwise it a virtual complete rebuild and nobody would any wiser by you doing it. What is the normal B+ voltage when loaded then? I like to have the caps rated at 50% higher otherwise their lifespan could be quite short and a transient take them out [emoji849]

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Thanks.  :-+ Actually I don't know what the B+ voltage should be. The schematic doesn't list it and that's the only documentation I've been able to find so far. It would be nice to have the complete assembly manual and so far no dice.

The original can contained caps with 450V rating so I used the same.
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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32677 on: June 06, 2019, 07:38:10 am »
Correction....the schematic does list the transformer secondary AC voltage into the 6X4 full wave rectifier as 360V. So there should be a considerable drop in the DC voltage as soon as I get a load on it.
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Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32678 on: June 06, 2019, 07:43:42 am »
Correction....the schematic does list the transformer secondary AC voltage into the 6X4 full wave rectifier as 360V. So there should be a considerable drop in the DC voltage as soon as I get a load on it.
That sounds more like it  :phew:, I was having visions of a cap spilling its guts everywhere.
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Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32679 on: June 06, 2019, 08:06:37 am »
Today, after I get back from shopping I'll be evicting those lockfit transistors as it turns out that 2N3904 (I have loads of these) is a good replacement for a BC148 and also BC108. Strange that because the schematic shows those as being BC108 and yet I have 3 Hackers, 2 are Sovereigns RP25's and the amp module is identical in all of them and they all have BC148 fitted which make me wonder if Hackers fitted them and never bothered to update their schematics or have these been fitted as replacements?

I noticed that on the good amplifier, the output transistors AC128 and AC176 that the coloured sleeving on their legs has melted calling for further investigation to find out if they have been subjected to high internal temperature or has someone lingered with the soldering iron to long when installing. I'm leaning towards the former as the heatsink has also turned blueish , better check the biasing on them. :palm:
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Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32680 on: June 06, 2019, 08:26:58 am »
Correction....the schematic does list the transformer secondary AC voltage into the 6X4 full wave rectifier as 360V. So there should be a considerable drop in the DC voltage as soon as I get a load on it.
That sounds more like it  :phew:, I was having visions of a cap spilling its guts everywhere.

There's a number of factors at play that will affect the B+ voltage. First, the power transformer is currently completely unloaded except for driving the filament on the 6X4 (6.3VAC) and the 1V2 (.98VAC). Second, when this scope was designed most residential line voltages were 110VAC - 115VAC. My line voltage is about 125VAC. After all is assembled and loaded I'll check the B+ and see where it's at. There is the outside chance that I may have to install a dropping resistor on the output of the 6X4 to bring it down so as to not stress the components.
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Offline bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32681 on: June 06, 2019, 09:03:13 am »
Today, after I get back from shopping I'll be evicting those lockfit transistors as it turns out that 2N3904 (I have loads of these) is a good replacement for a BC148 and also BC108. Strange that because the schematic shows those as being BC108 and yet I have 3 Hackers, 2 are Sovereigns RP25's and the amp module is identical in all of them and they all have BC148 fitted which make me wonder if Hackers fitted them and never bothered to update their schematics or have these been fitted as replacements?

I noticed that on the good amplifier, the output transistors AC128 and AC176 that the coloured sleeving on their legs has melted calling for further investigation to find out if they have been subjected to high internal temperature or has someone lingered with the soldering iron to long when installing. I'm leaning towards the former as the heatsink has also turned blueish , better check the biasing on them. :palm:

BC108 replaced BC148 mostly when the lockfits started failing. Probably expected them to release lockfits that weren't crap at some point but that never happened!

Check AC transistors for pin to case shorts. Occasionally they grow tin whiskers from the lead frame to the case. You can clear them by desoldering the transistor, soldering all its legs together, filling up a 2200uF electrolytic capacitor and stuffing it across case to the soldered together legs. The opposite transistor in the final pair gets pretty hot if the first one is short.

Anyway back to resolving my little nightmare. This planet's date and time handling is way too complicated :-- ...
 

Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32682 on: June 06, 2019, 09:34:06 am »
Anyway back to resolving my little nightmare. This planet's date and time handling is way too complicated :-- ...

Oh, tee hee.

Time/date is one of my favourite examples of "it is 10* more complex than you realise, recursively".

When I've come across arrogant ignorant developers/managers/specifiers/etc and they mention time, I start asking them questions like "how many milliseconds in 1s?" "how many seconds in 1min?"  through hours, days, months, years, century.

I've yet to have anybody give answers that are vaguely correct.

Then we can move onto the physics (and metaphysics) of how closely it is possible to sync the time of two computers. Very few have heard of Leslie Lamport, and it is a pain trying to explain it to them.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32683 on: June 06, 2019, 09:51:43 am »
Give them one of these and be done with it.  :-DD
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Offline bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32684 on: June 06, 2019, 10:17:54 am »
Unfortunately that brings meteorology, astronomy and astrophysics into the mix  :scared:

Anyway back to resolving my little nightmare. This planet's date and time handling is way too complicated :-- ...

Oh, tee hee.

Time/date is one of my favourite examples of "it is 10* more complex than you realise, recursively".

When I've come across arrogant ignorant developers/managers/specifiers/etc and they mention time, I start asking them questions like "how many milliseconds in 1s?" "how many seconds in 1min?"  through hours, days, months, years, century.

I've yet to have anybody give answers that are vaguely correct.

Then we can move onto the physics (and metaphysics) of how closely it is possible to sync the time of two computers. Very few have heard of Leslie Lamport, and it is a pain trying to explain it to them.

Indeed. This one is less concerned with second level accuracy but with what time things happened and are going to happen and to whom based on the interpretation of where all parties are currently. All parties and locations are potentially travelling humans who move across different time zones so perspective is important. Unfortunately nearly all the humans operators don't understand it either. To boot, the current scenario is pure ignorance of all of this. So here I am currently researching theoretical user scenarios to apply as test cases. I love doing this if I'm honest.

As for Lamport, yes indeed. It's sad but even compsci grads from the red bricks I have worked for give blank stares when talking about anything deeper than the organisational pattern of the magic beans someone sold them. Even if eating depends on it working. I actually mentioned paxos as a consensus algorithm in a pitch about 15 years ago and how they could be used to build a product for handling dynamic configuration management. I was laughed out of the room. Now everyone is all over it to the point that someone got a $1.9bn valuation and $100m in investment capital for it. Typical!  ::) ... could have bought some nice scopes with that.
« Last Edit: June 06, 2019, 10:19:58 am by bd139 »
 

Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32685 on: June 06, 2019, 11:01:56 am »
Unfortunately that brings meteorology, astronomy and astrophysics into the mix  :scared:

... and probably astrology as well. Too many people don't know the difference.

Patrick Moore gave a talk at my school, many decades ago. The local newspaper article called him a well-known astrologer.

Quote
Anyway back to resolving my little nightmare. This planet's date and time handling is way too complicated :-- ...

Oh, tee hee.

Time/date is one of my favourite examples of "it is 10* more complex than you realise, recursively".

When I've come across arrogant ignorant developers/managers/specifiers/etc and they mention time, I start asking them questions like "how many milliseconds in 1s?" "how many seconds in 1min?"  through hours, days, months, years, century.

I've yet to have anybody give answers that are vaguely correct.

Then we can move onto the physics (and metaphysics) of how closely it is possible to sync the time of two computers. Very few have heard of Leslie Lamport, and it is a pain trying to explain it to them.

Indeed. This one is less concerned with second level accuracy

Too many perps can't even get time ordering right at the hour level. I've see phone calls that have finished before they began.

Quote
but with what time things happened and are going to happen and to whom based on the interpretation of where all parties are currently.

Oh, that's more interesting. Do you have to account for the parties being asleep/drunk/have fat fingers etc?

Quote
All parties and locations are potentially travelling humans who move across different time zones so perspective is important. Unfortunately nearly all the humans operators don't understand it either. To boot, the current scenario is pure ignorance of all of this. So here I am currently researching theoretical user scenarios to apply as test cases. I love doing this if I'm honest.

In some ways that makes life easier for you, provided you have sufficient escape clauses in your contract and/or work. I once wrote a proposal for some hospital high intensity care equipment that stated it would not be suitable for life support applications. I pointed that out in the covering letter, and the client accepted it :)


Quote
As for Lamport, yes indeed. It's sad but even compsci grads from the red bricks I have worked for give blank stares when talking about anything deeper than the organisational pattern of the magic beans someone sold them. Even if eating depends on it working. I actually mentioned paxos as a consensus algorithm in a pitch about 15 years ago and how they could be used to build a product for handling dynamic configuration management. I was laughed out of the room. Now everyone is all over it to the point that someone got a $1.9bn valuation and $100m in investment capital for it. Typical!  ::) ... could have bought some nice scopes with that.

In ~1985 I wrote a proposal for something that would have been similar to Visio. I couldn't fund it. Oh well.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32686 on: June 06, 2019, 11:18:19 am »
"Escape" and "clause" are my middle names. Plus it's difficult to prove that I didn't make anything worse  :-DD

As for drunk / fat fingers, that's my worry. Because the blame is already assigned to a 100% correct running system before the user is considered at fault and it's the job of a support team to prove to the user that it's them.
 

Offline Brumby

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32687 on: June 06, 2019, 11:45:46 am »

"Lockfit" transistors? Never heard of them. Must be a British thing.  :-//
They are.

Not exclusively.  We had them here in Australia as well.

Lucky us.
 

Offline bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32688 on: June 06, 2019, 11:46:42 am »
Yeah we are well known for sending all our crap to Australia  :-DD
 

Offline Brumby

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32689 on: June 06, 2019, 11:50:14 am »
Hence the reason we send Fosters your way.
 
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Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32690 on: June 06, 2019, 11:55:29 am »
Update, lockfits not evicted yet, got wind of some special D day painted F15s departing Lakenheath for Normandy,. So I shot of to catch them on their return, snatched them on the 7D so may post them later. Might as well make a day of it now avoids the wasting of fuel then[emoji106]

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Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32691 on: June 06, 2019, 12:02:19 pm »
Let's see....do I want to wash the car this morning and work on the OL-1 this afternoon or vice versa?  :-// These are the heavy and earth shattering decisions you have to make everyday when you're retired and the rest of the world can go F themselves.  :-DD

The RCA scope will be worked on again next week. The parts for the HV supply won't be here until Monday. What to do this weekend?  :-// Oh, the humanity of it all.  :o ;D

Edit...that's right, I have to sweep/vacuum too. Now it's getting to complicated. I think I'll go back to bed.  :-+

« Last Edit: June 06, 2019, 12:07:56 pm by med6753 »
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Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32692 on: June 06, 2019, 12:15:09 pm »
"Escape" and "clause" are my middle names. Plus it's difficult to prove that I didn't make anything worse  :-DD

As for drunk / fat fingers, that's my worry. Because the blame is already assigned to a 100% correct running system before the user is considered at fault and it's the job of a support team to prove to the user that it's them.

I consider a prime use of "surplus unnecessary" inbuilt measurement and logging to be to deflect blame onto the other system that doesn't have it. I suppose that can be extended from "system" to "people".

It is a remarkably pleasant feeling when you can have a peacful weekend knowing that the other bustard is sweating away with their management on their backs. Bliss.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32693 on: June 06, 2019, 12:18:22 pm »
What to do this weekend?

In my case it is playing with HP3458As, some, LTZ1000s and a few other voltnuttish toys. Other people would be welcome to come.

Have to go over the bridge to another country, though, but get to see my daughter afterwards.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
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Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32694 on: June 06, 2019, 12:37:01 pm »
What to do this weekend?

In my case it is playing with HP3458As, some, LTZ1000s and a few other voltnuttish toys. Other people would be welcome to come.

Have to go over the bridge to another country, though, but get to see my daughter afterwards.

I'll do the yearly oil change on the Honda Civic on Sunday.

"Bridge to another country" ???? Last time I checked you had to take a tunnel to get to France, not a bridge. Or do you consider Scotland and Wales "another country" ? I guess in strict terms they are.   
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Offline paschulke2

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32695 on: June 06, 2019, 12:42:21 pm »

"Lockfit" transistors? Never heard of them. Must be a British thing.  :-//
They are.
Not exclusively.  We had them here in Australia as well.

I always thought they were a german thing. The BC148B in the image certainly is (manufactured by Siemens in West Germany)
« Last Edit: June 06, 2019, 12:46:03 pm by paschulke2 »
 

Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32696 on: June 06, 2019, 01:29:23 pm »
What to do this weekend?

In my case it is playing with HP3458As, some, LTZ1000s and a few other voltnuttish toys. Other people would be welcome to come.

Have to go over the bridge to another country, though, but get to see my daughter afterwards.

I'll do the yearly oil change on the Honda Civic on Sunday.

"Bridge to another country" ???? Last time I checked you had to take a tunnel to get to France, not a bridge. Or do you consider Scotland and Wales "another country" ? I guess in strict terms they are.   

Scotland is another country, with significantly different laws and legal system. Start by considering that trials can have three verdicts: guilty, not guilty, and not proven.

Wales likes to think of itself as another country, but is really just a principality[1]. >:D To emphasise their difference, all texts are written twice, once in English and once in a language where consonants appear in strange places and have even stranger pronounciations. Usually, but not always, the two texts mean the same thing.

English pedestrians in Cardiff were told to "Look Right" but Welsh pedestrians were told to "Look Left". I'm not sure which nationality was more likely to become strawberry jam.


This sign in Swansea told Welsh-speaking lorry drivers that "I am not in the office at the moment. Send any work to be translated".


But in this case the voltnut meetup will be in Caerdydd, which I am sure you will recognise is the capital city. I strongly suspect that is actually pronounced Cardiff, despite appearances to the contrary. That certainly isn't guaranteed, e.g. Newport/Casnewydd.

[1] yes, I expect that to provoke a, possibly justified, response in some people :)
« Last Edit: June 06, 2019, 03:25:15 pm by tggzzz »
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline grbk

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32697 on: June 06, 2019, 01:47:08 pm »
*snip*

*snip*

Unrelated, but did you install a backlight on your 8050A or is it a trick of the light?
 

Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32698 on: June 06, 2019, 01:50:38 pm »
I wish I could install a backlight on the 8050A. Just to the left hanging down is a small LED light pointed at the LCD.
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Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #32699 on: June 06, 2019, 01:55:59 pm »


Scotland is another country, with significantly different laws and legal system. Start by considering that trials can have three verdicts: guilty, not guilty, and not proven.


I definitely got that impression when I visited Scotland in 2001. They had just been given more autonomy to run their own affairs. And the Scottish flag was everywhere and the Union Jack was no where to be found.
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