I can highly recommend this (pretty cheap) device: https://www.ebay.com/itm/324672136249 (no, I don't know the seller 😀 )
I can't even begin to tell you how many issues (which were not apparent) I've fixed with it. 😀
It will show you ESR, VLoss, capacitance, everything you need to know to determine a cap's health (and many times, with just some exceptions, you can even test the cap while in-circuit)

Here's an example that I have from just this week.
The green capacitor is dead (the "well known" Chhsi bad brand), originally a 470uF/16V 😀, I removed it from a SS7 board that refused to POST, no matter how many times I tried. Notice that it doesn't appear to have any issues (no bulging, no leaking), in fact it looks pretty good.
The purple capacitor is a good 330uF/6.3V Sanyo cap, I removed it from a Socket 8 motherboard (VS440FX) that was in top shape, but I still wanted to give it the VIP treatment (since it's the only Socket 8 board I have), and replaced all its capacitors with new Panasonic FM caps.

The pics are probably self-explanatory (look at the ESR/Vloss/capacitance values on the green cap).
And, yes, the SS7 is alive and kicking after the recapping.

Bottom line, any retro enthusiast should have one of these. 😀

bloodem wrote on 2021-08-14, 09:43:

I can highly recommend this (pretty cheap) device: https://www.ebay.com/itm/324672136249 (no, I don't know the seller 😀 )

Bottom line, any retro enthusiast should have one of these. 😀

Well, thanks for the explanation!!
This is pretty straightforward.
Astonishing how it can affect a healthy board.

Aaaaaaaaaaaand... it's bought.
I added a recap job to the to-do list.

I removed a couple of caps and the board POSTs 4/5 times without too much trouble.
Less is better I think 😀

Nexxen wrote on 2021-08-14, 10:21:

Well, thanks for the explanation!!

You're welcome. 😀

Nexxen wrote on 2021-08-14, 10:21:

I removed a couple of caps and the board POSTs 4/5 times without too much trouble.
Less is better I think 😀

Well, depending on the circuit and on the health of those caps, I'm guessing that removing them could sometimes improve things. 😀
I would not use the board without those caps, though. Depending on their purpose, there's a chance that using the board like this might result in permanent damage of some other components (like ICs).

bloodem wrote on 2021-08-14, 12:15:

You're welcome. :-) […]
Show full quote

Nexxen wrote on 2021-08-14, 10:21:

Well, thanks for the explanation!!

You're welcome. 😀

Nexxen wrote on 2021-08-14, 10:21:

I removed a couple of caps and the board POSTs 4/5 times without too much trouble.
Less is better I think 😀

Well, depending on the circuit and on the health of those caps, I'm guessing that removing them could sometimes improve things. 😀
I would not use the board without those caps, though. Depending on their purpose, there's a chance that using the board like this might result in permanent damage of some other components (like ICs).

Not using it until recapped.
I'm already happy enough with it working again.
Unbearably hot summer days yield something finally!

Personally I can't see why such old boards can't get free schematics for repairs.
The retro community is there and kicking and it's not going to push down $$$ figures 😀

These testers are a good idea. I'm gonna get one myself. It seems using old boards with original caps is a disaster waiting to happen.

bloodem wrote on 2021-08-14, 09:43:

I can highly recommend this (pretty cheap) device

Which one of these do You have? The fake (FEJK) clone allegedly has altered PCBs, a smaller battery and a high failure rate.

Ydee wrote on 2021-08-15, 09:54:

Which one of these do You have? The fake (FEJK) clone allegedly has altered PCBs, a smaller battery and a high failure rate.

I didn't even know there were two versions. 😀
Anyway, yeah, I just checked right now and I have the fake/clone, with a 350mAh battery (I actually have two). I bought them 1.5 years ago and so far they've been great, had no issues with them.
Although, yeah, now that I think about it, the battery could last a bit longer. However, this has never been an issue for me... I'm not using them professionally anyway. 😀

Ydee wrote on 2021-08-15, 09:54:

bloodem wrote on 2021-08-14, 09:43:

I can highly recommend this (pretty cheap) device

Which one of these do You have? The fake (FEJK) clone allegedly has altered PCBs, a smaller battery and a high failure rate.

BTW, which is the best among the models?
I'm going to check and see what I'll get.

I really don't know about the versions and how many clones there are. I just want to buy some and I came across this link: http://www.hezkyden.cz/archiv/tc1-a-cinske-padelky/
That's why I wanted to know what version he had when he was happy with it and it worked.

Does the mfg of the originals have an eBay store?

There are a ton of different listings and would like to make sure I get an original.

cyclone3d wrote on 2021-08-15, 15:12:

Does the mfg of the originals have an eBay store?

There are a ton of different listings and would like to make sure I get an original.

I really don't know, but I wouldn't worry too much. I have the "fake" ones and they've really been great. 😀
I paid $30 for two, and have had them for a year and a half. If they last for 3 - 4 years it's all good, I got my money's worth. 😁

There seem to be multiple models - TC1, T7, T7-H. T7-H seems to be upgraded T7 with bigger display. TC1 is cheapest and should be enough.

There is also T4 model which works with regular 9V battery and comes without a plastic box. However it is possible to buy a transparent box for it. Another option is GM328A.

cyclone3d wrote on 2021-08-15, 15:12:

Does the mfg of the originals have an eBay store?
There are a ton of different listings and would like to make sure I get an original.

The original was designed and created (according to web sources) in Germany, The Chinese just "initially" took over and started production. On Ebay, Ali and elsewhere are then quality and lower quality clones. Probably the cheapest will be the most simplified, but a higher price does not automatically mean higher quality. They're identical on the outside.
We have a two-year guarantee here in the Czech Republic, so I'm not that worried about buying a clone or an "original". But of course I don't want to bother with RMA.

bloodem wrote on 2021-08-15, 15:49:

I paid $30 for two, and have had them for a year and a half. If they last for 3 - 4 years it's all good, I got my money's worth. 😁

Here they are with two-year warranty prices from $20 to $35, which is ok price. Thanks for answer!

AlexZ wrote on 2021-08-15, 17:35:

There seem to be multiple models - TC1, T7, T7-H. T7-H seems to be upgraded T7 with bigger display. TC1 is cheapest and should be enough.

There is also T4 model which works with regular 9V battery and comes without a plastic box. However it is possible to buy a transparent box for it. Another option is GM328A.

Yes, I know, everything built on ATmega.

Tested 2 caps, 6.3V 1500µF:

≃1620µF with 1.3 and 1.6% V-loss
Rubycon

Doesn't look bad for 20+ yrs electrolytic caps.

Well... if they're Rubycon, then that says it all. 😀
How's the ESR?

bloodem wrote on 2021-08-17, 05:48:

Well... if they're Rubycon, then that says it all. 😀
How's the ESR?

Shoot, I forgot to write it!

0.09 ohm and 0.06.

Probably I can leave all Rubycon a Nichicon and desolder all the others before starting with the more reliable brands.
20+ years and still doing well, kudoz!

I have to find a way to buy at stock prices in the EU, always wait from China makes every repair a months long job.

I got new caps and decided to desolder some and test them.
All Rubycon were still above spec, max 2% Vloss and 0.12 to 0.18 ohm.
And they are 20+ years old...

A few non Rubycon were 10% lower than rated and I replaced them.
These non Rubycon were moving on one leg or the other. Bad soldering job. By replacing them the board starts up as expected, no delays, no nothing.

Someone replaced them and I didn't check thoroughly.
My misery!!