Sony DVP-NS700P DVD Player Turns On Then Turns Off

[Optik]

Hello,

New poster here. I have a Sony DVP-NS700P DVD player that is many years old and just recently refused to remain on for more than a few seconds. It would wake up from standby, changing the red led to green, then promptly shut down after ~ 3 seconds, turning the led back to red.

I was able to temporarily revive it after removing the lid and poking around a bit. I checked a few voltages and they appeared OK. When it continued to happen, I searched and found the service manual.

I discovered I could revive it by using a hair dryer on the mother board (MB). It would then play for an entire evening without shutting down. However as time went on, this trick was less effective until it stopped working all together. I gathered that there was either a hair-line crack in a trace or solder joint that the heat 'fixed'.

It's sat on the same shelf for a long time. Hasn't been dropped, had anything spilled on it, etc. It's about 8 years old. I bought it new.

I haven't pulled any boards yet to inspect underneath, but I have looked closely at what I can see and see no evidence of overheating, no charred resistors, no leaking elec. caps, no burn marks. I need more mag on my magnifier though to carefully inspect 120 pin SMD's and all their traces on top of the board.

I've gone through the PS, checking voltages, and all but one are in spec. EVER +11 is spec'd at +- 1v. I read 13.7vdc. Likewise EVER -11 reads -13.7vdc. This is ~ 14% over the upper limit. I haven't yet found a cause. Perhaps parts/voltage variability?

I attempted to check some V's on the pri side of the switching transformer, in the FET switching ckt, but it doesn't stay on long, as it's quickly disabled by the SYS Cntrl IC. The +13.7vdc does stay on all the time. Perhaps this area needs further investigation.

According to the service manual, this thing has quite an extensive self-test/diagnostic test mode. Problem is I can't activate it in its present state.

The SM mentions holding a SELF CHECK pin low to force it into test mode. But the IC is on the underside of the IF-83 board and you have to remove the board to see the underside. Don't know how to do this without disconnecting it from the player. Also mentions shorting a land called "SELF" to enter test mode, but I see no reference to it on the top of the board nor in the reference sections of the SM. In other words, I don't see any separate trace leading to this pin to make access easier.

Found this in the troubleshooting section:

At POWER button ON, LED lights in green but returns to red (standby state) after several seconds. The PONCHK (30 pin) of the IF CON (IC404) on the IF-83 board is abnormal (slow rising from 0.5v to more than 1.5v or voltage not rising to more than 1.5v) The SYSTEM CONTROL (IC103) on the MB-100 board is faulty.
​

According to my Fluke meter, this voltage rises very fast to 3.4vdc, stabilizes there a few seconds, then immediately drops to 0v.

I pulled the transport out to have a look. The laser sled is all the way to the spindle. I'm assuming this is 'home' position. I've pulled & reseated several thin cables. No joy.

My guess is that upon power on, this Sys Cntrl IC checks several things and if one fails or is out of spec, it cuts off the power. Maybe it sees the + & - 13.7vdc, thinks that's a bit high so turns off.

Anyone seen this type of problem before? What was the fix? Suggestions? Comments? Yea, I know it's an old player but now I'm curious what's going on . . .

Thanks!

 

[(*steve*)]

Have a close look at the power supply. Look for capacitors that are bulging or leaking. This can be very subtle. If you have access to an ESR meter, then checking the ESR of filter capacitors is often useful.

When electrolytic capacitors begin to die, warming them up will often restore enough normality for things to happen. As things get worse, even this doesn't help.

So your experience is suggestive of this sort of problem.

 

[Optik]

Have a close look at the power supply. Look for capacitors that are bulging or leaking. This can be very subtle. If you have access to an ESR meter, then checking the ESR of filter capacitors is often useful.

When electrolytic capacitors begin to die, warming them up will often restore enough normality for things to happen. As things get worse, even this doesn't help.

So your experience is suggestive of this sort of problem.

No signs of bulging or leaking caps. I haven't checked the ESR of any yet. There is only one large elec. cap in the primary side that feeds the switcher, a 120uf, 200v. I'll post the PS schematic if you wish.

I didn't aim the hair dryer on the PS board at all. I kept it directed on the other side where the SYS CON. IC is. Thus I looked very closely in that area for physical signs of cracks, etc, since the unit would stay on (at least in the beginning) after heating up that IC and surrounding area.

Also, I'm having trouble searching this site for previous similiar problems. See my post in the forum help (I think. Not sure if I can go back there to get the right name without losing all the comments I've typed here!).

Thanks for the reply

 

[Optik]

Here's the PS schematic along with some voltages I measured. Most were done with the power switch in the on position, but the unit in standby mode. When you see a voltage that reads "11v then 0" or an arrow pointing to 0, it means that voltage was meas. when the PS was "on" for a few seconds before it went to standby. These voltages are software controlled and appear on the schematic as "SW+11v".

Since this PS won't stay on anymore than a few seconds, these v's return to 0v.

The ac v's on the pri side of the switching transformer were meas with respect to the '-' terminal of the diode bridge.

 

[Resqueline]

So the 3.3V & 5V never turn on? Q311 & Q611 should receive base drive as soon as the 11V turns on. Check for a track crack there. 0V on these bases is a giveaway.
Also measure for shorted b-e junctions, shorted C314, & shorted loads, just to make sure. SW stands for switched btw., even if it may be software controlled.
It's the 3.5V that's regulated (by means of IC301), thus the 11V won't be correct until the 3.3V (& 5V) receives a nominal load.

 

[Optik]

So the 3.3V & 5V never turn on? Q311 & Q611 should receive base drive as soon as the 11V turns on. Check for a track crack there. 0V on these bases is a giveaway.
Also measure for shorted b-e junctions, shorted C314, & shorted loads, just to make sure. SW stands for switched btw., even if it may be software controlled.
It's the 3.5V that's regulated (by means of IC301), thus the 11V won't be correct until the 3.3V (& 5V) receives a nominal load.

I believe the 3.3V & 5V do turn on initially, as P-CONT (pin 2 of CN201) rises to 3.3V. However, the sys control IC (on another board) detects some sort of fault or is faulty itself, and puts the unit back in stand-by via P-CONT. Q712's base is tied to P-CONT.

I equated SW for software because the switcher is running even in standby mode. Which means this part of the PS has been running for nearly 9 yrs straight as I've kept SW101 in the closed position, relying on the remote 'power-on' to wake up the player.

In other words, the decision to shut down the player is made on another board by the sys controller IC. What might be interesting is to tie pin 11 & 2 together and force it on. I can post other parts of the schematic if you're interested.

 

[Resqueline]

There's standby power outputs and there's switched power outputs (which are terms unrelated to the switchmode technology).
It's a little hard to assist in finding faults if the one can't trust the measurements/ notes. Don't believe, please measure/ confirm.
P-CONT being turned on is "unrelated" to 3.3 & 5V coming on. Please keep a distinction between measured facts and any theories you might have.
Yes, you could try to force it on like that to get better time to take measurements.
If it has any relevance, I find it odd that P-DET also falls to zero.

 

[dbeardsley]

Did you ever find a solution to this? I'm having the same problem and you've already done quite a bit of legwork. Thanks.

 

[Optik]

dbeardsley,
No I haven't. Had other things to fix, plus not many responded with additional clues. I connected +5V to the chip enable line (I think) attempting to force it on, but no joy. Because I was able to get it to power on for several months by simply pushing on the right hand side of the main board, I thought there might be a hairline crack in a trace, or a solder joint after 1000's of cold/heat/cold cycles, but it's just a guess.

Another idea is to separate the power supply control lines from the control IC, then see if it can be enabled with an external voltage.

Please post back with your symptoms and any clues you may find!

 

[shrtrnd]

Bending the board and seeing a change in operation would indicate to me a bad solder
joint (since you checked the trace). Use a magnifying glass or a loupe, resolder any
questionable connections.
I'm hearing a lot of problems lately with cold solder joints. This RoHS (lead-free) solder
is probably the culprit. It melts at a higher temperature than leaded solder. If the manu-
facturers are using a lower temp when they wave-solder the boards (to keep from damaging
the components or whatever), that might be the issue.
I work a lot of military gear. It's exempt from RoHS specifically because of this type
of problem. Hell. Maybe the RoHS solder is just brittle when they use it improperly.
RoHS sold because (from what I read), by the time these types of problems appeared,
(in cell phones, personal electronics, etc, ...) The devices would have ended their
service life anyway, and the customer should expect to just replace the device.
Big Brother watching out for you.

 

[Optik]

I recently picked up a SMD removal kit made by Chipquik. Worked really well for dealing with the lead-free solder on an iMac MB I repaired. Worked fine with my 30W iron. Amazing how well it works. I've fixed more BAD/COLD solder joints the last several years than ever before.....

 

[KJ6EAD]

Once you've generalized the location of a flaky connection on the board, you can often locate it more precisely by probing with a small plastic rod.

Another possible cause for your control system timeout is a read failure caused by a weak laser. The power output of diode lasers drops with age just like LEDs. Sometimes there's a trimmer pot you can use to turn it up a bit.

 

[Optik]

Thanks for the laser tip. I'll look on the schematic for an adjustment. I'll pull the board to examine the underside for any hairline cracks/solder joints.

I'm glad my thread has come back alive! Thanks to all for chiming in.

 

[Optik]

Stumbled upon this unofficial site for all things Sony. May be useful.

http://www.agoraquest.com/

 

[Optik]

I recently picked up a Sony DVP-NS300 at a garage sale for $15. Very similiar in front panel layout to the NS700P. Upon removal of the cover, I discovered two of the PC boards are common to both units, including the PS. The digital MB is different, as the 700P will output progressive video via YPbPr. If I recall, the IC that runs the power on check is on the board underneath the optical drive. Also, the 700P remote works fine with the 300.

I've been using a 17" PPC iMac as a DVD player. My neighbor was going to trash it due to a dark screen. Investigation revealed defective electrolytics on the MB. I recapped it and it lit on power up. Works great. Glad I got to it before the trashman.