Test Equipment Anonymous (TEA) group therapy thread

[Specmaster]

Jim Williams reckons that most scope problems are down to shorted tants, personally I have never found one yet that was shorted causing my issues 

[AF6LJ]

Nice catch.

I am at that point in my life I'll take the easy repairs any day...

[bd139]

Indeed. Quite happy with this

There is a video on YouTube somewhere of Jim Williams fixing a 465B with a shorted tant.

Couple more pictures ... the replacement capacitor with his little ferrite booties. This is a nice modern AVX one. If you ever have to clip these out, cut them close to the body, not the board, then you can pull the remaining legs through and solder replacements in from the top without having to get the interface board out. Plated through holes as always from tek so  to lazy fixes.



Chucked back together:



Identified problems so far:

1. Dirt.
2. The vertical volts/div switch is dicky on channel A. The vernier is crunchy and when you turn the main calibrated switch, it turns the vernier. Will dismantle and clean this out. might win
3. The fine horizontal position control pot is broken. These are ALWAYS broken universally on these. If I'm lucky I can pull the shaft forwards enough and do the grub screw up enough to hold it so it at least feels right.
4. More dirt
5. I have absolutely no idea how to use the time and 1/time settings!
6. Fan filter disintegrated (again normal)

[AF6LJ]

Good deal, another fine piece of gear saved from the landfill. 

[Specmaster]

There is a video on YouTube somewhere of Jim Williams fixing a 465B with a shorted tant.

Indeed and here it is

[mnementh]

Looks like I too am "Irreversibly contaminated" (a toast to anyone who gets that reference); I came in here to find a good home for a 454 with the intermittent HV fault that I've been meaning to fix for 20 years. I haven't used the thing since I got a 2230 at an estate sale before my son was born.

Anyways... I just got that piece of mail every guy dreads; the "Welcome!" letter from AARP. As you can imagine, this does tend to have a bit of a polarizing effect on a man, and after some consideration and a cup of coffee, I figured it was time to just let the old beast go.

I took a few minutes with a rag to clean the front and replaced the fuse "one last time to take photos"; it's been running a while and has that familiar smell of warm dust and wax and of course now I can't. I just can't.


*weary sigh*

mnem
*Raises a glass in memory of Dave*

[bd139]

That ones a beauty. Thanks for the nice photos.. I’d drag that one to the grave with me

[Specmaster]

I have to say, seeing these nice photos of 454 and 475 on here, I'm getting broody, I like construction and the attention to detail, ooer... I can feel my control slipping away here fast, already have enough projects and another arriving any day now, it could be getting joined by another 

[bd139]

You’re well in now. It escalates pretty quickly.

 I’ve actually decided to only buy stuff I need at the moment. In the case of the 475 I’m in the middle of building an HF transceiver PA stage and I suspect that it’s oscillating as there is a vast difference between what my other scope and my RF power meter are reporting. The 475 does indeed show it is oscillating.

[AF6LJ]

You’re well in now. It escalates pretty quickly.

 I’ve actually decided to only buy stuff I need at the moment. In the case of the 475 I’m in the middle of building an HF transceiver PA stage and I suspect that it’s oscillating as there is a vast difference between what my other scope and my RF power meter are reporting. The 475 does indeed show it is oscillating.

I have to say, seeing these nice photos of 454 and 475 on here, I'm getting broody, I like construction and the attention to detail, ooer... I can feel my control slipping away here fast, already have enough projects and another arriving any day now, it could be getting joined by another 

It's all about control and organization, line up the projects for the next couple of years like this...
This year..
Finished HL-2200 amplifier all that is needed is some testing and a pilot lamp replacment.
Next.. (and every second week of the month) radio club paper work, being the secratary I have to get it all together by Thursday.... (fourth week Newsletter)...
Next real project.. HP-8569B number two...
Then..
The Motorola Micom 500E HF radio (microphone preamp design, and control computer hook up)
Tek 2440 next.. (CCD error)
Atlas 350XL and power supply
Tek-475 refresh
Hallicrafters HT-32 transmitter repair and rehab.
Bad Oscar (Heath SB-221 customization)
Tek 453 repair (maybe)
IFR FM/AM 1000s repair.
That is the list for 2017-end of 2018.
That leaves enough wild hair wiggle room. (that spontaneous project that should take a week but takes two months.)

[djos]

Well that was annoyingly easy. The tant on the end of the 15v rail was shorted - C1448.  Diagnostic process:

1. Measure rails and reference voltages.
2. Go through them in order.
3. Measure resistance of the tants. Ooh 0.27 ohms. That sounds like a short! Snip it out.
4. Power up. No explosions.

Bingo:

<SNIP>

Going to replace this (I actually have a replacement in stock for once - 10uF 25v) run through and measure ripple, clean it and calibrate it as best as I can with my limited kit. ESR on ALL of the big electrolytics is good.

 

Nice work sir.

Sorry for the n00b question, how do you accurately measure Capacitor ESR in circuit?

[bitseeker]

Identified problems so far:

1. Dirt.
2. The vertical volts/div switch is dicky on channel A. The vernier is crunchy and when you turn the main calibrated switch, it turns the vernier. Will dismantle and clean this out. might win
3. The fine horizontal position control pot is broken. These are ALWAYS broken universally on these. If I'm lucky I can pull the shaft forwards enough and do the grub screw up enough to hold it so it at least feels right.
4. More dirt
5. I have absolutely no idea how to use the time and 1/time settings!
6. Fan filter disintegrated (again normal)

So far, so good. Looks like a nice save.

It's all about control and organization, line up the projects for the next couple of years like this...

That's quite a to-do list, Sue. Congrats on all the neat gear in the queue.

That leaves enough wild hair wiggle room. (that spontaneous project that should take a week but takes two months.)

Yeah, tell me about it. There are the non-electronics ones, too. My "honey do" list is longer than my workbench.

[bd139]

Nice work sir.

Sorry for the n00b question, how do you accurately measure Capacitor ESR in circuit?

Cheeky hack this one. You don't do it accurately: not possible!

1. Use your DDS to stick a 100kHz 100mV square wave into the cap under test. 100mV so you don't make any silicon junctions conduct.
2. Connect a scope across it.
3. Measure amplitude A.
4. Stick another known good cap across it in parallel.
5. Measure amplitude B.
6. If B is more than about 5% greater than A, then the DUT is likely knackered.

[djos]

Nice work sir.

Sorry for the n00b question, how do you accurately measure Capacitor ESR in circuit?

Cheeky hack this one. You don't do it accurately: not possible!

1. Use your DDS to stick a 100kHz 100mV square wave into the cap under test. 100mV so you don't make any silicon junctions conduct.
2. Connect a scope across it.
3. Measure amplitude A.
4. Stick another known good cap across it in parallel.
5. Measure amplitude B.
6. If B is more than about 5% greater than A, then the DUT is likely knackered.

Lol, nice one!

I Assume DDS = Function Generator? Now I have another item to add to my required equipment list.   

[bd139]

Yep any old function generator will do.

[Specmaster]

Nice work sir.

Sorry for the n00b question, how do you accurately measure Capacitor ESR in circuit?

Cheeky hack this one. You don't do it accurately: not possible!

1. Use your DDS to stick a 100kHz 100mV square wave into the cap under test. 100mV so you don't make any silicon junctions conduct.
2. Connect a scope across it.
3. Measure amplitude A.
4. Stick another known good cap across it in parallel.
5. Measure amplitude B.
6. If B is more than about 5% greater than A, then the DUT is likely knackered.

Thats a handy trick, I always lift a leg out and stick my ESR meter on it then and with tants, just use a multimeter on low ohms. Next time I'll try this trick. 

[mnementh]

That ones a beauty. Thanks for the nice photos.. I’d drag that one to the grave with me

Thanks... there's some history there. Doesn't help the nostalgia a bit that it was likely manufactured the year I was born.

Opinions... like my 2465s and my 2230, the rubber has long ago disintegrated on this one. I'm thinking about trying my hand at designing and 3D printing some replacements. Do you think the Tek gods would frown on such substitutes?

mnem
Things that make you go "Hmmm..."

[bitseeker]

I'm thinking about trying my hand at designing and 3D printing some replacements. Do you think the Tek gods would frown on such substitutes?

Surely, that would be better than the whole thing taking up space in a landfill.

[CalMachine]

Not your Typical Test Equipment but I like to consider this lucky find, an Artifact!    When I find items like this for $200 on Ebay, it makes me want to never log off.   Help... Me...













Now only to put it to use!

[bitseeker]

Wow, with docs!

[URI]

Not your Typical Test Equipment but I like to consider this lucky find, an Artifact!

Great Find! 
..and together with its documentation it's a really precious instrument. Worth the money! 

I have a Philips PM 2535 with a mode for measuring PT100s and show the results in °C with 0.1°C resolution best; that would be like cast pearls before swine.

Do you have an instrument precise enough to use this temperature sensor?
If not so you have to go for it now, urgently! 

[mnementh]

Time to take up chocolate-making as a hobby.


mnem
mmmmmmmmmmm.... chocolate...

[Zucca]

My TEA is getting worse... TopLoser is killing me with those prices. Help please!

[Mr. Scram]

Because I'm careful with my equipment, I bought a case for my Fluke 87V on eBay. That way, I'm sure it will be safe when it's not in use. Today, I got my 87V out and what do you know: black marks on both sides of the holster from the strap of the case. I've been trying to get them off with soap, methanol or gentle scraping, but no dice. It looks like they're here to stay.

Sometimes you just can't win. Stuff like this kills me.

My TEA is getting worse... TopLoser is killing me with those prices. Help please!

Same here. It's terrible!

[bd139]

I have been fortunately way too busy to notice his deals until the stuff is all gone

475 is cleaning up nicely. Did this corner and the CRT bezel today at lunch time: