Panasonic top-loader VCR Issues

[vortalexfan]

Its finally working! I just left the VCR plugged in over night and tried it out this morning and its been working fine ever since.
I watched Bruce Lee Enter the Dragon all the way through without any issues.

[redk9258]

I'll bet it's a cap that's bad. Maybe leaving it powered on reformed it.

[vortalexfan]

Originally Posted by redk9258

I'll bet it's a cap that's bad. Maybe leaving it powered on reformed it.

That's what I was thinking, but I wasn't sure where the cap was, or what board to begin to look at for that cap, because there are about a dozen circuit boards inside of this VCR and some of them aren't the easiest to get to, and the Sam's wasn't much help in regards to telling me which board controlled what, and they didn't really have a troubleshooting section in the manual to trace down certain issues with.

[vortalexfan]

Well I just started working on the PV-1650 VCR the other day and I replaced all of the Belts and had the play idler rebuilt by Gary over at the Voice of Music Enthusiasts and the VCR is still having issues with not wanting to play a tape after loading the tape up to the heads.

I have a copy of the Factory Service Manual from Panasonic that I got from Sam's which they sent me that because they didn't have their own service manual for the PV-1650 uploaded into their server database and that manual was very helpful (a lot more helpful than the Sam's Photofact manual for the PV-1750 was).

I figured out that there is a board that specifically drives/controls the loading and playback mechanism of the VCR (more or less the logic board for the VCR that controls whether the VCR mechanism plays, rewinds, fast-forwards, pauses, etc.) and so I removed that board from the VCR and looked it over and sure enough basically every single capacitor on that board was bad (either dead or had an ESR measurement of 2 Ohms or higher) and was also leaking electrolyte.

So I'm working on recapping that logic board so I can see if that will fix the VCR so it will play again.

Hopefully I'll have an update soon that will be a positive update where the VCR is working again (or at least mostly working again.)

[redk9258]

Good luck!

[vortalexfan]

An Update on the PV-1750:

I had an issue with it not working again and it turned out that the Audio Board and the Servo board both had some higher capacitance capacitors on them that I wasn't able to change previously because I didn't have those capacitors on hand, the servo board had a 100μF 16V capacitor and a 220μF 16V capacitor and the Audio board had a 220μF 16V capacitor that all three of those caps were leaking electrolyte out of the bottom, and so when I was finally able to replace them, the VCR started working properly again and its been working fine since.

The only thing I've noticed is that, when I go to turn on my 1974 GTE/Sylvania 25" Color Console TV that I have it hooked up to (so I can have a vintage setup) and play a tape on the PV-1750 the fine tuning on the TV gets screwed up and I have to re-fine tune the tuner on the TV until the picture locks in, any ideas as to what might be causing that issue?

Attached is a picture showing a bag full of capacitors which are all of the capacitors I replaced in the PV-1750 VCR to get it going, the other picture is showing my 1974 GTE Sylvania 25" Color Console TV with my Panasonic PV-1750 VCR hooked up to it and sitting on top of it, which is my vintage/retro TV Setup for watching VHS movies on and playing my NES and SNES games on, also I've noticed that after un-pausing a video the picture takes a few seconds to stabilize once its stabilized the video is perfect and plays fine.

[redk9258]

Good work!

[ARC Tech-109]

The RF modulator is off frequency internally, don't know if they can be trimmed back. The electrolytic capacitors are always a problem. 35+ years of heat/cool cycles and rubber seal deterioration they're going to fail, some show it more than others. My first Sony DVW-A500 DigiBeta died from leaking electrolytics, they dissolved the traces from the PC boards.

[vortalexfan]

Originally Posted by ARC Tech-109

The RF modulator is off frequency internally, don't know if they can be trimmed back. The electrolytic capacitors are always a problem. 35+ years of heat/cool cycles and rubber seal deterioration they're going to fail, some show it more than others. My first Sony DVW-A500 DigiBeta died from leaking electrolytics, they dissolved the traces from the PC boards.

Thankfully none of the traces were damaged in this unit.
And I was able to remove the capacitors without any damage to the solder pads.

As for the RF Modulator goes, I'm not sure if it can be adjusted or not, I'll have to look and see if the RF Modulator is actually removeable in the PV-1750, I know the PV-1650 has a removeable RF Modulator module that has adjustments, but I'm not sure about the 1750.

[ARC Tech-109]

Most were a module as some areas needed a channel 2/3 or 3/4, I've even seen a channel 5/6 that was in a JVC Vidstar. Sony used a trimmer cap in theirs but anything goes with Matsushita, you could try tweaking the core slug in the modulator to see if that shifts the frequency enough for your sets AFC to grab on to, the other issue might be the AFC in the set is thermal and cold causes it to drift outside it's range. Without actually checking the carrier of the sources against a known standard it's difficult to say whos drifting around. I use a Motorola R2670 service monitor for my reference, it's only +8hz off a Stamford FS725 rubiduim standard on the 9th harmonic.