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Discussion Starter · #1 ·
Hello everybody. First time poster, long time lurker here. I'm a laserdisc fan who had the recent good fortune to pick up an apparently barely used Mitsubishi M-V7057 (rebadged CLD D-704) for cheap. This is about how high up the laserdisc player ladder I plan on climbing unless I happen upon a superior model for dirt cheap. By this logic, I'd like to get this player in perfect running shape to use as my main player. Upon getting the unit hooked up to my av setup and testing it out (last summer) I've run into some issues that I'd like to solve which I'll highlight below. I'd like to preface this by saying that I have a great respect for others who have direct experience working on these players and I'm not the type to ask dumb questions and expect people to provide all of the answers for me. My hope is that these community experts will chime in and guide me on my quest to tune up my unit. I've got basic soldering experience, having replaced faulty capacitors on some old electronics, so I'm not afraid to get into the nitty gritty component replacement.

While using the player the other night, it outright died on me. Now that I have to crack it open to figure out what went wrong, I figured I'd post here first to glean all the info I can from others and be armed with the best knowledge to get this beast in pristine functioning shape. That all being said, here's the rundown of the problems I was experiencing before it quit on me:

The main issue I find is that when the disc spins up from a dead stop, I hear a scuffing/spinning noise for a couple of seconds before it gets up to speed. I understand that this is probably the clamping mechanism not adequately grabbing the disc. When I had the unit open awhile ago just to peek at the innards, the spindle side of the clamp looked clean and free of gunk, so it may be that it is simply old and worn out. I did not look at the upper portion of the clamp as I was just peeking around, but I will address that in this round of examination. Is there a preferred cleaning fluid to restore the "grippyness" for lack of a better term to the clamping mechanism?

The second issue I experience is that about 70-80% of the time when the disc begins to play, the image on the screen looks reminiscent of a VCR with tracking problems, that is to say, large portions of the image are distorted and jump back and forth across the screen. The playback also appears to stutter. By stopping and starting playback a couple of times, the issue usually goes away. I'm hoping someone with specific knowledge of laserdisc circuitry can speculate about what is causing this and what I can do to correct it.

The third issue is that the disc takes forever to stop spinning once playback is finished. Upon reading some other posts on this forum, I gather that this can stem from clamping problems, so hopefully, by addressing the clamp, this problem will go away, but I figured I would mention it in case there are other rpm sensors etc that should be checked while I have it open.

Finally, now that this unit will not power up at all, I have to address the power supply. As I said, I have yet to open it up, but I expect to find a main fuse blown as not even the power indicator light will come on. When the power died, there were no strange symptoms. I hit stop, and the whole thing shut down and would not turn back on. Obviously, I'll try replacing the main fuse, but I'd love to know if anyone has any thoughts on what could cause the power supply to fail in such a non-symptomatic manner, as I would hate to just replace the fuse and have the problem manifest itself again.

Thank you all for taking the time to read this lengthy first post, and I hope to learn from the community here and end up with a working player again!
 

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First hope your good debugging a switching mode power supply as you need to get that working first. Once that is going you need to order a VEB1237 grip ring too replace the one on the spindle motor, it is too old to rejuvenate, will only last a short time, but a new replacement.
 

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Discussion Starter · #3 ·
So I took the deck out of my very crowded entertainment unit. Just for kicks I plugged it in to a wall outlet and glory be, it turned on. At this point I figured I would plug it back in in the entertainment unit. It still works plugged in to the same surge protector it was in the first place when it refused to turn on. It should be mentioned that when it first refused to turn on the other night, I tried plugging it in to 2 other power sources and still didn't get anything. So either there's an intermittent problem with the power supply or I'm losing my marbles. Thank you for the part number Kurtis, I'll order a new grip ring and hopefully that will solve the spinning up/braking issues. Now that the thing will turn on, I'll try to get a video of the distorted picture and post it here so you guys can see what I'm talking about.
 

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Discussion Starter · #4 ·
I looked up the part on pioneer's website and it says they want $14 to ship it fedex ground! That's nuts, for a little rubber ring? I guess I shouldn't complain considering that pioneer still actually carries a part for a player thats about 15 years old :) I guess I'll bite the bullet and get it.

As far as the weird video goes, I recorded a video of the symptom. I had just switched to side B and it started doing it. Sometimes it does it right off the bat on side A when I hit play, sometimes not. The forum requires me to post 5 times before I can attach a photo or video, so I'll do it right.....
 

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Discussion Starter · #10 ·
Update. I haven't yet ordered the grip ring yet, but I was tinkering around with it to try and find some repeatability with the other symptoms. While I had it open to listen for weird noises, I cleaned the grip ring. It helped the first time it spun up but not after that, so as you say Kurtis, it's probably just old and worn out. I'll definitely be ordering a couple spares. I've found some repeatability with the power and skipping issues:

The skipping happens when starting playback on side A. The player makes a sound like it's trying to find the right place to start reading the track. This takes a few seconds longer than normal. Then it starts playback but skips around, forward and back while trying to play. If I skip forward, it will do the same thing on the next couple of chapters, but eventually if I skip forward far enough it will lock on to the track immediately and cease the skipping. At this point if I skip back to the beginning of the disc, it will play normally.

As far as the power goes, after hitting stop on the player, once the disc free-wheels down to a stop, when I press the power button, the power goes off and stays off. It's supposed to click over to standby mode, but it doesn't. If I unplug it for about 30 sec, something resets itself and when I plug it back in, the standby light is on again. This is repeatable. I don't know anything about the construction of switching power supplies, but I suspect that there's some component that is failing to switch it back to standby.

Any advice is welcome regarding these developments. I'd love to shed some light on them especially if it means ordering other parts from pioneer so I can lump them in with the same order to save on shipping.
 

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Sounds like the 1uf starter capacitor may be going in the power supply, Pioneer does not have any replacement parts so I suggest doing a master swap all electrolytic capacitors in the supply. Sometimes you also can see a fluctuation in brightness in the background as the capacitors start to go bad.
 

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Discussion Starter · #12 ·
Sounds like the 1uf starter capacitor may be going in the power supply, Pioneer does not have any replacement parts so I suggest doing a master swap all electrolytic capacitors in the supply. Sometimes you also can see a fluctuation in brightness in the background as the capacitors start to go bad.
I've done some capacitor replacement before. It shouldn't be too bad. I actually prefer working on older electronics because they have bigger solder connections with lots of space around the components. It's a lot harder to foul up than newer stuff. I'll order some caps and report back. In the past I've just made sure that the microfarad rating is the same, but on mouser or digi-key there are tons of other parameters to choose from. Is there any other criteria that needs to be considered for the type of caps for a power supply?
 

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Discussion Starter · #15 ·
Replaced the grip ring. It greatly helps spin up/down and side change operations. I still occasionally get the wobbly lines in the image. Seems to be less so lately, but we have had warmer temperatures and more humidity which i know can affect failing electronics. While I had it open, I jotted down all of the capacitor values on the power board. I'll order them up at some point soon. I also dod a brief check for cold solder joints on the power board, but nothing jumped out at me. I'll post back when I get to the caps. Thanks again for your help thus far….
 
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