The Sony DVP-N900V and the curious case of the cold IC!

adpopulum

Well-Known Member
Picked up a minty Sony DVP-N900V the other week for free knowing that it was not working. The issue is when I power up the unit it turns on for about three seconds (green light) then goes into standby mode (red light). When in standby mode pressing “play”, “open” etc. will start the cycle over but it won’t turn on. Did a quick search online and found someone describing the same symptoms as well as a temporary “fix” using a hair dryer! Well I immediately though this was a case of someone jumping to conclusions attributing an effect to an unrelated cause and I parked that “solution” in the back of my brain. I got myself a copy of the service manual and lo and behold, right there in the troubleshooting section is described this very condition. Apparently it is a faulty IC. I had a look at the board and found the culprit. Everything looked good (i.e., no signs of excessive heat or water damage). Then I recalled the story of the hairdryer fix and remembered that this fellow had applied heat to the same board that housed this IC… for shits and giggles I went upstairs and borrowed the wife’s fancy new hair dryer and in about 15 minutes the damn thing fired up and was playing CDs perfectly! I listened for about an hour then shut it down. Turned it on and off a few times and all seemed normal so I went upstairs and had some dinner. About an hour later I was back to the same original state of not coming out of standby mode. So back at it with the hair dryer and on she went again. This time I left it on all night (certainly long enough for the heat from the hair dryer to dissipate) and in the morning it was still running properly. I assume as long as there is current running through the IC it will continue to work. After it was off for a while the original state returned.

I doubt there is an easy or cheap fix for this and it will likely wind up as a parts donor but I am curious as to what is going on here? Can anybody explain why heat would temporarily fix the issue?
 
My first thought was a cracked/cold solder joint but I can't imagine that the hair dryer comes anywhere close to the heat needed to melt the solder. Maybe it's hot enough to cause a part to expand, causing it to shift and then make contact until it cools down again? But, I'm not really sure what the IC is you're talking about, could you post a pic of the piece in question, maybe some close-ups of it and where it connects to the PCB, etc.?
 
I agree. My thinking is that it is a faulty chip as opposed to a cold solder. Anyhow, here is a pic of the IC in question (IC104).IMG_3066.JPG
 
The TV in my man cave is like that. I used to flip the power surge protector off when I finished hanging out down there since I only go down there on weekends. The TV began to have a blurry picture upon powering up, which went away after it had been on for 20 minutes. Now, I leave the surge protector switched "on," and have had no problems since.
 
That's a really unusual failure mode. Usually you run into problems from parts overheating, not from being too cold! Unless you're dealing with vacuum tubes, of course. ;)
 
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