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Replacing Motherboard In Philips DVP3068/94
This DVD player made the second visit to my workshop (after a gap of one year) with the complaint that it stops after playing for some time. This had visited me during July, 2016 with the complaint of ‘NO DISK’, and I had written an article on it earlier. That time, apart from solving the problem, I had also done preventive maintenance service. But as mentioned earlier, this DVD player is being used continuously for hours together by the customer for reasons already explained. (http://jestineyong.com/no-disc-error-dvd-player/)
When I checked, I found that it was intermittently working and stopping when it worked. Checked the voltages on PS Board and found these to be – 8 and + 5 exactly even on load. So that section was ruled out. I noticed that uController was getting extremely hot and one resistor was burnt in the main board. So, I removed it and found that the bottom of the uController IC was dark!
Checked and found that there were no other defective components in the power supply section and ESRs of all caps were within the limit. Hence there was no other go, but to replace the mother board, as getting a replacement of uController was not available in the market and moreover, I am not yet fully confident of replacing the IC with its hundreds of tiny pins! It was rather a ‘spidery’ scare for me!
The mother board that we get readily from the market is a general board that unfortunately will not interface with the front control panel. It will work only from the remote. I connected a universal mother board with a new SMPS which has +5V and -12V required by the mother board. The SMPS of Philips had only +5V and -8V. So, I could not use that. Took two two-pin connectors from my stock and directly soldered the other ends to Power Supply Board. Interchanged the connections of Tray for sliding motor, loading motor and spindle motor by sliding out the metal sockets from the connectors, to suit the connections on the new board, as these were different from Philips mother board. (Since I had already covered about such connections and mother board change in my previous articles, I am not repeating these here). Interchanged the connections of USB connector and made it matching. Did the same for control panel, to enable IR detection and Power LED.
Since the universal mother board needs an ‘end’ (or starting position) switch feedback from the interface with the tray, and these were not there in the Philips original mother board, the need to fix a ‘push to on’ switch arouse again. Unlike last time, when I fixed a salvaged leaf switch, I used a small button switch and after experimenting the movement and studying the position, fixed it like before, wiring it to the two vacant pins on the connector PCB:
Connected the boards and tray after rechecking everything and power it on. It worked, but it was not taking all CDs, especially DVDs, showing either ‘disk error’, ejection or continuously spinning without any indication. The laser light was present in the Eye unit. But I could play only a few CDS. This is an indication that the eye unit has become weaker. So, replaced it with a new one. This eye unit has a peculiar cutting for the sliding gear that moves the eye across the CD.
After that I played the CDs and found that with the new eye unit, though more number of CDs were getting accepted, it was not playing DVDs and certain CDs. So, adjusted the gap of the spindle platter (slightly increased the gap between the motor and platter). It then worked very well. This is important. The focal length of eye unit may not be the same that of the one which was working earlier. So, we need to adjust it on trial and error method. Now the DVD player was working very well taking up almost 26 DVDs/CDs I tried.
Since the arrangement of RC sockets behind the mother board were different from that of the Philips Mother Board, I plucked the RC sockets from the defective board and fixed it at the rear panel and wired these to the mother board externally.
You will notice from the above picture that the Video out was at the bottom left, but in the new board, it was reverse and it had some other connector also under the Video out. That is why I resorted to this transplant! Having seen how the IC got burnt in the previous board. I fixed a mini cooling fan, wiring +12V to the SMPS (This is not used by the mother board and was free) and placed it near the IC for cooling it. (Sorry, forgot to click all these!)
Closed the covers and allowed it to run for many hours continuously, playing one CD after another and intermittently trying USB too. It worked very well without any problem!
So, another job finished to my utmost satisfaction! (Customer took delivery a few days back and reported that her son was very happy to have the player working, listening to his favorite songs!)
This article was prepared for you by Parasuraman Subramanian from India. He is 68 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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