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Posted: 11 Apr 2020, 16:56
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SpyroGyro, You made my day!!! I perused your great photo's and funnily enough I had tried the wheel with the belt, but after a few turns I saw nothing happening! Now, with your help I kept turning much longer and found that in one direction it seems to come to a stop, so I changed to the other direction and sesame (!) after a couple of turns it started to move and had the tray out in a few minutes.
Fantastic, thanks ever so much my dear fellow. Now we can get on with further examinations. :angel: |
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Posted: 24 Jul 2020, 09:41
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O.K. Here's what happened and how it was solved: Somehow the DVD carriage had missed the front switch ( which will remain a mystery why) and had jammed up against the barrier stopat the front as described earlier.
Placing the carriage back re-generated some function but the teeth of the first cam that's driven by the worm wheel was damaged. Under a strong magnifier with a Stanley knife blade that I somewhat heated I was able to "re-model" the teeth to an acceptable level. Takes a lot of patience. Then it worked but not reliably. I discovered that the DC motor now and the stopped and just hummed. Removed it from the carriage after extracting the carriage from the mechanism. Result with the Lab power supply (6V) of the bench: The motor had failed! It measured 12 Ohms in all positions which is good but still it would'nt start on its own and vibrated when running. Found another motor in a slightly older Pioneer LD player and used that one as a replacement. Result: Everything runs beautifully again especially since I also used the better cam from the defective donor unit. It's like new again. |
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Posted: 29 Jul 2020, 17:14
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After extensive exploration the problem is solved and I'll try and give a description of what has been found etc.
The fault that paralysed the unit was the overshoot in forward direction of the DVD laser carriage. It went all the way forward and rid up against the mechanical end stop whilst practically losing contact between the carriage drive cam and the track. With some effort the carriage was placed back on it's track and moved to halfway back. Switching the unit on again resulted in an awakening but after a few trials the same thing happened again.
Clearly the end switches were disregarded. To do the above ánd to get acces to these switches one must remove the upper part of the loading mechanism (the part fastened by 4 black screws) and some attachments. Then the 2 switches (white nylon) become visible through two holes in the bottom of the chassis. Since getting to the switches would require much more disassembly it's good to notice that they are connected with a flat cable to the CLDM assy, see service manual p.17 LMSB assy Switch S 104 & 105 that connect to the lower horizontal CLDM board CN 102.
If you want to check the (normally open) switches, you can check this with your Ohm meter on the flat cable end at CN102. However, the manual has made a mistake that is essential to be aware of. The flat cable is a 10 contact one.
CN101 on page 40 (that shows the board LMSB assy with the switches) shows 12 contacts (!!!!). This is a mistake copied from an earlier model. CN101 is a 10 contact connector. What's even more complicating things is that they have turned the connector 180 degrees around. This alters the numbering. So what is drawn as 10 is actually 1 and 1 is actually 10! (11&12 do not exist). Then 6 is earth switches to be measured against 7 & 8 (contact switches). If the switches show resistance when pressed in gently one could try and give them a short squirt with a mild contact cleaner via the pressed in button(s). A good clean of the flat cable where you do the measuring is also recommended.
When all this is done it's a good time to look at the condition of the gears of the carriage. If the gear that engages with the worm wheel of the motor is damaged, you might use a warm Stanley knife and try and "remold" it under a magnifier. Many have been saved that way and it's a good thing to do carefully because these gears are no longer available. In my case I was succesful in the remodeling. A further complication was that I found the DC motor had lost 1 of it's 3 windings and was a write-off. I ordered a identical looking and numbered one from Aliexpress only to find that the number is a "case-family" nr. and did not relate to voltage.... It was much too fast, which was a diappointment. Luckily a friend had a earlier LD Pioneer parts unit that held the same motor!
So in the end I was able to replace the remodeled cam ánd the defective motor and all is perfect now.
Hope this gives some support to people with the same symptoms. If you progress with care and use a few pages from the service manual ánd take a few pictures before taking things apart, nothing will go wrong. Good luck! |
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