JVC HR-S7722 recap?

[radiokom]

So, yesterday I received JVC HR-S722 from vcrshop.
It worked but to my wonder power supply was not recapped.
Because commonly it is a first job to any old switching power supply.
And I noticed one 2200µf cap goes really hot soon after switch on.
So I decided to recap PS. Now all is fine.
And the moment of truth:
Resistance test of that 2200µf capacitor show 5,2ohm so it is defective.
It means even decks from vcrshop needs additional service.

[lordsmurf]

Most techs live by the motto "ain't broke, don't fix it", because trying to needlessly repair old electronics can be tempting fate, with negative outcomes. Cascade issues are real, and can be a nightmare.

While a cap getting hot isn't good, it's also not necessarily at risk of imminent failure.

Fix it now, or fix after it fails? There's really no one right answer here. Risks exist both ways.

Or he may have just missed a non-obvious failing cap.

[radiokom]

Quote:

Originally Posted by lordsmurf

Most techs live by the motto "ain't broke, don't fix it", because trying to needlessly repair old electronics can be tempting fate, with negative outcomes. Cascade issues are real, and can be a nightmare.

While a cap getting hot isn't good, it's also not necessarily at risk of imminent failure.

Fix it now, or fix after it fails? There's really no one right answer here. Risks exist both ways.

Or he may have just missed a non-obvious failing cap.

Those switching power supplies, if not recapped, is ticking time bomb. Recap is really not a rocket science and new high quality 105degree caps all together are about EUR 6-10. It took me about 2 hours (because I have never disassembled JVC before, Panasonic with K mech is more service friendly because of separate boards) That 2200µf cap with constant 5,2ohm resistance is really dead, so not other tests are required (it would be like doing a blood test on a dead horse). So my rule Nr.1 for those - always to replace all PS capacitors first no matter they are up to specs or not. But only PS capacitors.

[lordsmurf]

That's why, in this specific case, I think he just missed it. How did it look beforehand?

[radiokom]

Quote:

Originally Posted by lordsmurf

That's why, in this specific case, I think he just missed it. How did it look beforehand?

Deck worked as it should (perhaps), simply I was curios how it looks inside and found PS still has original caps. But it is really impossible to measure them without disassembling unit and however there is technology to test capacitors without removing (at least my friend, engineer has devices and know how how to do it, but you need access to legs anyway), in real life you simply test it after removing (and, if removed, replace with new because there is really no reason to solder back old one) or simply replace them all and forget. This is what I do. In this case I simply touched PS capacitors by finger (initial test ) and found one is extremally hot, so there is real failure somewhere. So I recapped all PS and measured this particular capacitor with multimeter (advanced testers I have in another location, now I am in my summer house). Result was as expected.

-- merged --

But aside of that, I starting to understand why you prefer JVC Even if it is not "day and night" if compared with Panasonic, on first sight (at least for my eyes) JVC picture looks a bit better if compared with Panasonic NV-HS950 and NV-HS1000. However it may be an illusion, so further tests needed. But yes - this is very good deck.

[timtape]

A problem with SMPS power supplies is that even in standby mode they can run hot especially certain caps. Heat shortens the life of gel based electrolytic caps.

My approach is to avoid problems before they arise. Avoid this this heat as much as possible. So for my AV appliances which can only be switched into standby mode I plug them into a multi point power board with individual switches. If I can see the clock display lit up in a disc or tape machine and I'm not using it, I switch its mains off at the power board. It's a long term strategy and switching off or on at the power board only takes a moment. Most of my VCR's and disc players are decades old and are still on their original electro caps.

So often in life, prevention is better than cure. Sure the caps will eventually fail but if with a little knowledge and vigilance we can delay that by 10 years we're ahead.

[radiokom]

Yes, but that's like putting off going to the dentist by regularly rinsing your teeth with whiskey instead. Those PS capacitors are well known troublemakers, so - recap with new 105degree and forget. It is cheap and really simple. And if are talking about serviced decks, it always include PS recap (in case of switching PS).

[aramkolt]

I do full recaps of my AG1980 power supplies (including the main filter cap) mainly because their power supplies are kind of noisy (audibly and electrically) to begin with, but it's rare for the original capacitors to actually "test out of spec" ESR or capacitance wise and they don't run hot when in use. This is likely because their power supplies use Panasonic capacitors and the power supply doesn't throw as much heat as some others. I haven't seen any other "professional" AG1980 refurbishers replace anything in the power supply other than perhaps the starting cap on the primary side which is like a 22uf 25V capacitor if I recall correctly.

In my experience, it is relatively rare for Chemicon, Rubycon, Nichicon, or Panasonic caps to to test bad in final generation VCRs unless they are in very high heat areas. Most switching power supplies only have a couple of components that normally run hot.

An example of that being the SVO-5800 that is full of 105C Nichicon caps, but they almost always are all bad because the entire power supply runs quite hot under normal operation as it isn't ventilated particularly well.

[radiokom]

Well, for capacitors is not good if the device is not operated for a long time. Secondly - high loads in switching power supplies, no cooling etc. Thirdly - average original capacitor quality. They die, it is a classic. And when they completely die, they took other parts with them. I have never understood those who do not go to the dentist for a long time, until they finally wait for that Friday evening (always Friday), when the tooth finally starts to hurt so much that they have to go to the blacksmith to pull it out.

[lordsmurf]

Quote:

Originally Posted by radiokom

Well, for capacitors is not good if the device is not operated for a long time.

Again, risks exist both ways. If left plugged in, risks. If left unplugged, risks. All you can do is pick the path with the least perceived risks.

I unplug anything that won't be used for 2+ weeks, because odds are that it may not be used for 4+ weeks or even 4+ months. I'm more worried about power loss (that last longer than UPS). To a degree, I play this both ways. I risk half my gear by leaving it plugged in, and half by leaving it unplugged.

I've done this for decades, and gear loss from power events is much greater than gear left unplugged for extended periods.

Quote:

I have never understood those who do not go to the dentist for a long time, until they finally wait for that Friday evening (always Friday), when the tooth finally starts to hurt so much that they have to go to the blacksmith to pull it out.

For most, it's about costs, followed by time needed (time off work). Not that I agree, but that's it.

[radiokom]

Quote:

Originally Posted by lordsmurf

For most, it's about costs, followed by time needed (time off work). Not that I agree, but that's it.

Hmmm.... If about cost, all capacitors cost me about EUR 6 all together (good brands, Nichicon, Jamicon, Elite etc., they are all about the same quality) from trusted local seller, and 2h to recap (for next JVC it will be 1hour including mechanics cleaning and lubrication).

But if they fails - then you should find a tech who can repair switching power supply, and then it will be different expenses (I have a friend engineer, who do it at sight, but anyway I prefer to "recap and forget").
No, I do not agree that stand-by mode have negative effect on PS capacitors. But in short - "recap and forget". Other capacitors, outside switching PS, fails rarely.

[lordsmurf]

Quote:

Originally Posted by radiokom

Hmmm.... If about cost, all capacitors

I was referring to the dentist.

"Most people" don't recap for obvious reasons: too hard, don't know what to do (or why).

Quote:

But if they fails - then you should find a tech

Back to costs, time needed. No just time to take it (or ship it somewhere), but time to even research why the problem exists, to learn that caps are to blame.

For reasons above, techs are mostly "ain't broke, don't fix it".

Don't get me wrong here -- I think you're doing something great, and going "above and beyond". But you're the unicorn shouting into a void. If I weren't a pragmatist, I'd put my arm around your shoulder, and shout with you.

Quote:

No, I do not agree that stand-by mode have negative effect on PS capacitors.

It really depends on model. JVC DR-Mx recorders, for example, are never "off" unless unplugged. So I leave those unplugged 99% of the time. Used on as needed, excellent DVD recorders.

[timtape]

Quote:

Originally Posted by aramkolt

I do full recaps of my AG1980 power supplies (including the main filter cap) mainly because their power supplies are kind of noisy (audibly and electrically) to begin with, but it's rare for the original capacitors to actually "test out of spec" ESR or capacitance wise and they don't run hot when in use. This is likely because their power supplies use Panasonic capacitors and the power supply doesn't throw as much heat as some others. I haven't seen any other "professional" AG1980 refurbishers replace anything in the power supply other than perhaps the starting cap on the primary side which is like a 22uf 25V capacitor if I recall correctly.

In my experience, it is relatively rare for Chemicon, Rubycon, Nichicon, or Panasonic caps to to test bad in final generation VCRs unless they are in very high heat areas. Most switching power supplies only have a couple of components that normally run hot.

An example of that being the SVO-5800 that is full of 105C Nichicon caps, but they almost always are all bad because the entire power supply runs quite hot under normal operation as it isn't ventilated particularly well.

Yes, apart from cap quality, heat and time seem the usual causes of elecrolytic cap failure. As you say, poor ventilation in some decks can shorten capacitor life due to higher average temperatures. I have too many decks both audio and video to be regularly recapping even all of the PSU's. When a customer asks me to play or digitize their tapes I first test my relevent machine and if needed service it. For that is the time a deck is used.

There are different opinions about full recapping vs recapping only the caps that are causing deck faults. As so often in life there are tradeoffs. It's not always clear cut.

[radiokom]

Quote:

Originally Posted by timtape

There are different opinions about full recapping vs recapping only the caps that are causing deck faults. As so often in life there are tradeoffs. It's not always clear cut.

If we are talking about devices with switching power supply there is a reason to recap only power supply, but to replace all caps in PS (if you started why leave there old caps?). In audio cassette decks (they has normal, not switching PS), like Nakamichi CR7 there are only few potential troublemakers in PS, bet if you start to replace 2 caps why not to replace them all. In Studer and Revox all capacitors should be replaced no matter where they are. Frako all tends to short, blue Philips loose their value (some are 2/3 out of specs). But in VCR I would not mess with those caps aside PS. They fail very rare and after full recap full calibration could be needed, but after PS recap you do not need to calibrate anything.

[timtape]

I agree with some of what you say. It also depends on who is doing the recapping.

For a wider representation of views and comments, here is a discussion thread on a UK forum specifically dedicated to repair of vintage electronic equipment. You will probably find your own views represented there.

https://www.vintage-radio.net/forum/...d.php?t=131568

[dpalomaki]

Be aware that in switching PS some (not all) caps may be marked on the schematic as requiring exact replacements for safety reasons.

The 5.2 ohm reading needs to be qualified. Was it DC with correct VOM lead polarity, reversed polarity, steady reading, a starting reading that changed as the cap charged, ESR, etc.

[radiokom]

Quote:

Originally Posted by dpalomaki

The 5.2 ohm reading needs to be qualified. Was it DC with correct VOM lead polarity, reversed polarity, steady reading, a starting reading that changed as the cap charged, ESR, etc.

Constant 5.2ohm reading has only one qualification - cap is dead. Dead as a brick. What health tests, and for what purpose, are you going to perform on a dead horse?

[dpalomaki]

Quote:

What health tests, and for what purpose, are you going to perform on a dead horse?

A little snarky there. For a confirmed failed cap, none beyond check for physical fit of a replacement, and verify specs in the service manual.

However, unlike resistors, capacitors often can give different readings depending on how they are measured and the results can all be stated in ohms.

[radiokom]

For capacitors are 2 basic tests - capacitance and ESR. None of them should be performed on dead caps, because it is considered desecration of a corpse (at least in the PAL zone) and is punishable.