Quasar VCR Model VH-420 - Testing of Power Supply?

Peter Smith: Forget trying to measure voltages, if they were not near being proper the machine would not be operating as well as it is, and if you were to measure voltages you really need a scope to look for ripple and regulation problems.... The fault is most likely dry, leaky or otherwise faulty electrolytics. If you do not have an ESR meter to test them, just replace ALL of the electrolytics in the SMPS, not that many and not that expensive. After you are done fixing the power supply you need to clean the VCR tape path paying special attention to the A/C head..... build up on the lower part of that head will cause tracking problems and fluctuating tape flow...... so will a bad tape.

-- Best Regards, Daniel Sofie Electronics Supply & Repair

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The most probable diagnosis is high esr electrolytics in the power supply. Don't waste your time trying to test them unless you have an esr meter. Replacing all of them in the power supply (approx 8 - 12 ) will likely cure the problem you are having with the VCR. electricitym . . .

Peter Smith wrote:

Thanks for the fast replies.

Sofie, I cleaned the heads and the tape path first, and I didn't notice any improvement. I really am not comfortable repairing the PS myself, I was just going to tell them the cost of a rebuilt supply if they wanted to get it fixed. I doubt they'll want to spend much on this unit considering it's age, but I do want to make sure that I made the correct diagnosis. Is there much of a chance that it might be something else? To describe the picture a little further, it's mostly black & white with a lot of snow and lines, in addition to the speed fluctuating about twice per minute. Thanks Again.

Hi Peter...

Can't get my TV to turn on yet; but I've done about a gazillion or so vcr's...

If I get a vote I cast it in favor of cleaning the tape path. Pay extraordinary attention to the control head (furthest left viewed from above, head the tape contacts first before the video heads)

A few new q-tips and a little isopropyl alcohol. After you finish cleaning it then clean it again :)

Then re-do the video heads. And again.

Don't be tricked into testing by playing a tape that's been recorded on this same machine (at least not while it was 'dirty') Playback a tape from a known good machine. Or a commercial tape.

Take care.

Ken

Ken: You are right about the control head, but actually Ken, the control head (A/C Head) is the furthest right..... after the video heads and exit roller guide.... right before the capstan and pinch roller. The lower part of that head, if it has any kind of build-up or debris on it can cause the symptoms Peter Smith mentioned in his original posting. The head that you mentioned on the left that first head that the tape touches on the left before it goes past the roller guides and video drum is the FULL ERASE HEAD and problems with that head would not produce any bad symptoms when playing back good pre-recorded tapes.

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Best Regards,
Daniel Sofie
Electronics Supply & Repair
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"Ken Weitzel"  wrote in message
news:cpDwe.120960$El.64286@pd7tw1no...

> Can't get my TV to turn on yet; but I've done about a
> gazillion or so vcr's...
>
> If I get a vote I cast it in favor of cleaning the tape
> path.  Pay extraordinary attention to the control head
> (furthest left viewed from above, head the tape contacts
> first before the video heads)
>
> Ken
>

Ken Weitzel: The head you just described is the full tape erase head and is only activated when recording. The control head certainly could be the culprit as described by Sofie. The A-C head (audio-control) head is the LAST head that the tape touches the right side just before the capstan and pinch roller... then the tape goes back into the cassette housing. A thorough inspection and cleaning of that head is warranted. Also trying other tapes as you suggested is a good plan because as you know, damaged, worn, or improperly recorded tapes can cause the exact symptoms. electricitym . . . . . .

Ken Weitzel wrote:

Arghhh. You're right of course, Sofie.

I did warn you guys that I'm getting on in years, and not handling it at all well, didn't I? :(

Sorry about that.

Ken

Ken: Since Peter mentioned that the problem ALSO shows up on just the TUNER output without the tape playing it is a good guess that the power supply might be the problem. Faulty electrolytics in the SMPS can cause all kinds of picture problems off the tuner and the tape playback mode. Then as we all surmised a good cleaning of the audio-control head and the entire tape path would be in order. electricitym

. .

"Peter Smith" ha scritto nel messaggio news:k6Dwe.13837$ snipped-for-privacy@twister.southeast.rr.com...

Hum, are you sure that the price of the fix is worth the value of the VCR and of a new VCR ? I STRONGLY recommend you to repair your PS by yourself !!! But be careful, there are 200-350VDC on the primary side !!! Let the capacitors descharge before repair it, or connect a small bulb (i.e. 40-60W) to the terminals of the biggest capacitors, to descharge it and work safely !!! To learn more about safety and SMPS read this group's faq at

!!!

I.

It's definitely worth it recapping the power supply in that VCR. That's an early-mid 90's Panasonic-made VCR, and those power supplies were notorious for the electrolytics going bad. He's probably seeing the early stages of capacitor failure, the VCR will eventually not power up at all.

We have the same model VCRs in my wife's store for recording the security cameras. It was in the store when we bought it in 1998, and has been recording 16 hrs/day, 7 day/week since then. (The rest of the video equip. has mfg. dates of 1996, so the VCR was likely put in service about that time) I don't think any new VCR would hold up under that kind of use. Which is why I plan on replacing the video heads on it when they finally go(SP died a couple years ago, but EP is still holding on.)

If the OP doesn't have an ESR meter to test the caps, just replace all the electrolytic caps, except maybe the large 160 - 200 volt cap on the

primary side. I use low-ESR, 105 deg. Nichicon caps, I order from Mouser Electronics. They don't have a minimum order (the caps will total < $10), and they don't rip you off on shipping fees.

Mike WB2MEP

"WB2MEP" ha scritto nel messaggio news: snipped-for-privacy@o13g2000cwo.googlegroups.com...

See:

Those are great VCRs, but making the PSU work is a bit tricky :-)

It didn't need to be changed !!! Change all the caps on the secondary !!!

I.

"nolsar" ha scritto nel messaggio news: snipped-for-privacy@rogers.com...

Yess ! I *love* flea markets and yardsales, because people didn't know what they do have, and I buy some interesting stuff most for 0.50?, 1?, 2? max.

5? !!! At the flea-market of my city there was a good Philips VTR *6 HEADS - HIFI*... the vendor said "I don't know if it works, but for 10? is good" !!!

I.