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  #1  
08-18-2020, 12:35 PM
fraghop fraghop is offline
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Hi all,

I have been lurking here for some time as I came into possession of a Panasonic AG-7150 through a church auction. This VHS playback device is my daily driver, and as of late has been having some trouble.

For the first ten minutes or so after the device is powered on, there is a tracking issue where snow comes in from the bottom of the screen to the top of the screen. This will happen every ten seconds or so, and during this time the timestamp does not increment on the device, and the stereo audio signal goes in and out.

I have a feeling something with the tape transport may need to be adjusted, but I am not sure. I was wondering if anyone else has had this issue before and if I simply need to make a slight adjustment.

Thank you!
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Someday, 12:01 PM
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  #2  
08-18-2020, 01:18 PM
latreche34 latreche34 is offline
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Clean the combo sync pulse head and audio with alcohol and q-tip (DO NOT use it on the video drum), Cleaning tapes don't do much on stationary heads especially if the VCR is being heavily used as you described.
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08-18-2020, 02:53 PM
hodgey hodgey is offline
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This guy had a similar tracking issue in the AG7350 (same model with recording capability) caused by a bad cap, may be worth checking if cleaning the A/C heads does not help.
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06-17-2021, 06:21 PM
Shakedown St. Shakedown St. is offline
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I would like to report I am experiencing the same problem with these Panasonics.

My model is the AG7350. The 7350 and 7150 are surprisingly robust machines compared with the 1970 and 1980. Way more reliable and easy to repair than the 7750. The 7350 and your model have only one known problem. There are three or four capacitors on the capstan servo circuit that overheat from lack of ventilation and fail overtime. It will show this symptom as the tape counter not counting, and the tape will constantly go in and out of tracking. Signals from the control head are disabled.

This is one of the few major maintenance requirements when buying a used one. Most of them for sale out there will have this problem or it will eventually fail on yours. Very accessible and easy access. However these decks are worth it because of their great external sync controls, so I can lock them to a TBC and use as a capturing deck. It is known for being the best 6 hour speed VCR that was ever built but will only track in mono audio in that mode.

Ben Klesc
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06-17-2021, 07:09 PM
timtape timtape is offline
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I agree. I have a 7350. They don't do long play though.
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  #6  
06-17-2021, 09:37 PM
Shakedown St. Shakedown St. is offline
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Quote:
Originally Posted by timtape View Post
I agree. I have a 7350. They don't do long play though.
You're probably right but there is a little investigation I am doing. Apparently some of them had the ability to play SLP tape but not LP tape. The PAL version does not. Some NTSC versions do have a separate head and I am determining whether the one I own may have that feature.
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06-17-2021, 09:56 PM
timtape timtape is offline
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Quote:
Originally Posted by Shakedown St. View Post
You're probably right but there is a little investigation I am doing. Apparently some of them had the ability to play SLP tape but not LP tape. The PAL version does not. Some NTSC versions do have a separate head and I am determining whether the one I own may have that feature.
Right. Mine is PAL. Normally I'd expect LP record function to be selectable from the front panel. Maybe with NTSC it's selectable in the menu? Still sounds strange though.

Have had the same cap problems with the capstan servo board. Caps replace fixed it.
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06-19-2021, 09:07 AM
hodgey hodgey is offline
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Quote:
Originally Posted by Shakedown St. View Post
The 7350 and your model have only one known problem. There are three or four capacitors on the capstan servo circuit that overheat from lack of ventilation and fail overtime.
Hm, both the ones (PAL AG7350) we have here have developed two other issues but not tracking problems.

Firstly there is some image disturbance on VHS (but seemingly not s-vhs) tapes. More recently the one I was using has started shutting resetting most of the time when trying to start playback. I haven't found anything about either issue online. I already checked for bad caps in the power supply (and replaced a bunch I probably didn't need to as most seemed to be good) and the video boards, only one that I remember being high ESR was the 400v 1uf one in the power supply, though those are known to fail over time as far as I've seen and cause startup issues.

The SVHS sub-board used in this and other decks also seem to have some SMD caps that can fail over time, and cause bad or missing output for SVHS playback, though that seems to not be an issue so far (it's one of these hybrid IC boards that are annoying to fix.)

Which of the servo board capacitors go bad? I suppose it's not impossible that that could cause other issues too like the reset issue which is presumably some issue on the servo board.
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