Philips MDP 3380/12 Blu-ray Player – No Power, Reset Signal Always High

[ictc]

I'm troubleshooting a Philips MDP 3380/12 Blu-ray player that shows no signs of life. The display remains off, and no buttons respond.

Inside, the power supply is working correctly, and all expected voltages on the mainboard match the service manual specifications. The CPU warms up slightly (checked with a thermal camera), the crystal oscillator is functioning, but the reset signal remains high at all times.

The reset circuit appears to consist of two NPN transistors, one driven by 5V VCC and the other by 3.3V STBY, as shown in the attached schematic. Should the reset signal always stay high in this case? Pressing the buttons has no effect, and the display remains completely off.

Any insights would be greatly appreciated!

[truclacicr]

RESET_ should start at 0V immediately after power-on, and then rise to 3.3V. It should then remain at 3.3V until the next power cycle. You could always short RESET_ to ground to restart the player, if you suspect that it is not resetting properly.

[lotas]

Connect to the UART (TX, Rx, GND) and through the terminal see what it displays, the problem may also be in the NAND memory, a firmware failure...
Also check the signal lines on USB, HDMI and LAN for resistance relative to GND.

[Diah]

its much error at micro switch at CD unit... try to do drive CD in manual with yours finger to rool it up down and the laser head to have up with little click... then inser it in wall see if it reject the CD out

[ictc]

Thank you all for your input, though I still have some doubts. No evidence of shorts was found on the ETH and HDMI ports. However, I did notice signs of corrosion on R190 (a large 0-ohm resistor connected to HDMI_VCC) and a small mark on the PCB that made me think a spark might have occurred. You know when, after a spark, the PCB shows a halo with various color gradients, likely due to the evaporation of some metallic oxide? In this case, the phenomenon is almost imperceptible to an untrained or inattentive eye, and I might have overthought it or exaggerated its significance. There's no actual damage to the copper, just a very slight discoloration on the solder mask, which can probably be removed with IPA. The resistor measures fine, though.

As for the display being completely off, could this really be caused by a microswitch on the DVD unit? I believe that under any operating condition, the display should remain on, both when opening and closing the tray. Since it remains off, I tend to think the issue lies elsewhere—possibly firmware-related, as the display is also managed by the microcontroller.

In any case, I suggested a more in-depth analysis to the customer, but the repair cost would be comparable to that of a new unit. Understandably, they declined the offer. So, I appreciate everyone's help, but I have no option other than to reassemble the product and return it to the customer.

Regardless of whether the issue is firmware-related or a NAND failure, the repair would still be excessive and not cost-effective. That said, does anyone know if there's a way to attempt a blind firmware reflash in this condition? An update is available, but I'm unsure whether it's feasible given the device's current state of total inoperability

[ictc]

update, the client doesn't want it back so I can give a try eventually.

[nomoresonys]

First thing I suspect in old units is bad caps, they can make them show no life in many cases. Might not be the problem but I always test them first.

[ictc]

do you mean the electrolytic capacitors on the mainboard? I allready checked the SMPS and they are fine so far... the unit still perfectly clean inside perheaps not used very often.

[nomoresonys]

Sure, might be worth checking. The led display unit may be bad but if that was the only problem, I think the player would still work thru the tv display and the buttons and such would still work. Can you post some good pictures of these internals.

[nomoresonys]

You did hook it up to a tv yes?

[ictc]

You did hook it up to a tv yes?

Of course, no signs of life. Also tested the only 2 caps on the motherboard and they tested fine too.

[nomoresonys]

Did you try post #4, manually release the tray, things go smoother if you relay that you tried a given suggestion. Before you say I already did that, it IS not clear if you did or not, you just give an opinion.

[ictc]

Did you try post #4, manually release the tray, things go smoother if you relay that you tried a given suggestion. Before you say I already did that, it IS not clear if you did or not, you just give an opinion.

Yes, I'm sorry for not expressing myself clearly enough. I manually released the tray using the access point under the casing, specifically designed for manual ejection. I had to do that at the beginning in order to remove the front panel. I did it once again just to be sure but it didn't have any effect. Thanks again!

[ictc]

By the way I also was unable to find the UART as suggested in another reply ...

[lotas]

Look for contact points RX, TX.