Question PS2 SCPH-77004 only starts for one second

[dawid90u]

I'm asking you for help in repairing my PS2 SCPH-77004 (motherboard model GH-051-02). I received it in unknown condition and I don't know its history.

Before connecting the power supply, I checked for short circuits on the main board. It turned out that the short circuit was on the 47uF/16V capacitor near the 4914 integrated circuit and the coil. I replaced the capacitor.

Its current state is that the red diode on the front panel is lit. After switching on, the green diode lights up for a moment (about 1 second) and the red diode lights up again.

All fuses that I found are OK.
The 78M05 voltage regulators are working. 5V appears for a moment when turned on.
I power it with a laboratory power supply (8.5V/5.1A). During switch-on, there are no voltage drops on the capacitors where the voltage is 8.5V.
Under thermal imaging, it does not appear that any components heat up very much when turned on. The 579A IC heats up slightly.
As I found correctly (I use the SCPH-70000 service pdf), it is a voltage regulator. 3.5V and 1.8V. The resistance on pins 5 and 7 is high. There is a voltage of 3.5V and 1.8V on these pins.

I don't have schematics for this version of the motherboard. I'm wondering if I shouldn't give the required voltages to try to "force" the console to start. But I don't know if that's a good idea. Something is cutting it off and I can't find what.
I will also add that this console had MODBO 760 installed. I removed it but the effect is the same.
When I turn on the console with the button, I can slightly hear the voltage converters turning on in the area of the capacitor that had a short circuit.
I also tried reading data from Serial EE SIO. But I can't locate the pins for this motherboard version. I tried searching but no pins near EE generated Serial data (Checked with logic analyzer).
I am also posting photos of the motherboard from both sides.


Do you have any ideas what I could check?
Best Regards,
Dawid

 

[dawid90u]

Hi again,
In my free time I still try to repair the console.
I have reached the point that no voltage is generated on the DIG_+1.2V1 and DIG_+5V voltage converters. This voltage is generated by MOSFETs controlled by the MB39A116 IC. In the 70000 series schematics, the SN105233DBTR is used.
There are no waveforms at all on the pins (27, 29 and 17, 19) controlling the gates of the mosfets. I thought it was the controller's fault. I replaced it but no change. The mosfets are of course functional.
After turning on the console with the button, the state of the STBY1 and STBY2 pins is high. Does this IC require additional states on pins? Unfortunately, I have not found any documentation for it.

I tried to connect the required voltages after the converters. When applying 1.2V, EE+GS heats up slightly.
After connecting 5V, more integrated circuits heat up. But the one in the picture heats up more clearly. Unfortunately, I am unable to locate it on the diagrams for the 70000 series. Its temperature reaches 70 degrees (C). Its marking on the chip is "I403 983-170" I think this is too much.

Unfortunately I don't have enough converters to connect all the required power supplies and check if the console will come to life. I just ordered them.
What I wonder most is why I cannot start the MB39A116.

In the previous post I wrote that I only have a green diode for one second. For testing I lifted the second leg of the MM1579 chip. The second pin is responsible for RESET. Now the green diode is constantly on, which allows me to verify all voltages.

Maybe someone can help me what I could check next.

Best Regards,
Dawid

 

[FatBaldDad]

I am following your progress with great curiosity. I have a few boards that do this and have set them aside for future endeavors like this—lol!

 

[leftbrainstrain]

What you're doing is far beyond my ability, but I did some digging on the part you asked about.

The part with label "I403 983-170" happens to be in the same place as a Microchip part with label "561H" on a later GH-051 board revision (on the psdeviki site), though the parts look different. On the GH-061 boards used in many 79k models, the Microchip part with label "562F" looks very similar to the "561H" part. In the 79k compendium the "562F" part is in the lower right corner and layers with names "3.5v [Top layer]" and "2.5v reg2 [Top layer]" intersect it.

 

[FatBaldDad]

Any progress?

 

[danringer]

http://www.gmt.com.tw/product/datasheet/EDS-983-XXX.pdf

mine has the 983-170 chip also. says it's a 1.7V regulator.

 

[dawid90u]

Hi again,
Unfortunately, my adventure in motherboard repair has come to the end. I damaged the CXD9209GP...
The 983-170 chip turned out to be functional. Correct IN/OUT voltages.
Generally, I powered the motherboard normally by applying 8.5V to the DC connector. Additionally, using DC-DC converters, I applied 1.2V and 5V to places where they were not.
It looked like it wanted to work. But the fan still didn't work and there was no video on the monitor. And then the worst happened...
I noticed that there is no voltage on the 7805 stabilizers. And I made a big mistake here. I connected the 5V from the converter to the input instead of the output of the 7805 circuits.
Probably after powering the board, 8.5V appeared on the inputs of the 7805 circuits. And 8.5V could have appeared on the 5V line.

Now I have full short circuit on the 1.5V line. During the short circuit test, the CXD9209GP very heats up.
Unfortunately, I do not have preheater to replace this IC and I also do not have a working IC to swap the circuits. It's a shame because I really wanted to fix this PS2.
Still, I'd like to thank you for your willingness to help.

Best Regards,
Dawid