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CPS3 board issue

BladeZX

BladeZX

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I have a cart from Darksoft and the CPSIII ultra simm kit but when I power on the board with just the cart I get this
It seems to be missing 1, 6 and 7 and there are color issues

Anyone have any ideas?
 

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Start by making sure the cartridge and slot are super clean. Give the cart a good cleaning with cotton swabs and isopropyl alcohol.
 
Are you able to test the CU383’s located at 8D, 9D & 10D? If those go out, those can have color issues as they govern the R, G and B outputs. I might check if any of their pins might be loose. The resistors at R5, R6 or R7 could also have cold solder.

The odds of all three of these dying at the same time, however, are slim. Based on your symptom, I’d also check the pins/chip of that Motorola chip @ 9C as well.

Are any of these mentioned chips running hot when the board’s powered up?
 
Gave everything a good cleaning - still the same
This makes me sad as I just got my ultrasimm kit today LOL

How can I test the CU383s? What would I need to test them

No chips get hot

This does look suspect
 

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Last edited:
Your security cart looks fine. That piggybacked chip in your post from yesterday looks very dodgy - can you post a zoomed out picture so we can see where it is on the board?

Jotego has preliminary schematics available for CPS3 - page 10 has the video DAC which is definitely where your problem lies.
https://github.com/jotego/jtbin/blob/master/sch/cps3.pdf

When you look at the schematic, you'll see the CU383s at 8D, 9D and 10D. You'll want to test them with a logic probe or oscilloscope. They should read High on pin 24 (+5 Vcc), Low on pin 12 (GND) and have logic pulses on every connected pin. If the pulses look weak or nonexistent on some of those connected pins and you've confirmed continuity from the pin to its destination then the CU383 chip should be desoldered and replaced.
 
ShootTheCore said:
Your security cart looks fine. That piggybacked chip in your post from yesterday looks very dodgy - can you post a zoomed out picture so we can see where it is on the board?
Click to expand...
Those are the photocouplers connected to the kick harness at CN1

BladeZX said:
Thanks @ShootTheCore
I have an oscilloscope so I will check those chips and see what I get

For the PS2501-4 chip
Can u tell me where pin 4 and 6 go to on the one closest to the edge of the board
Click to expand...
Look at page 3 of the schematic.
 
The 8D, 9D and 10D chips all seem to have the correct activity on them
I did notice that PPU at 2G gets pretty warm - not sure if that is normal
 
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