Now that I've got the linear power supply to acceptable stability (https://forums.arcade-museum.com/showthread.php?t=409438), I've moved on to the MCR stack.
Here's what I've done so far:
- Replaced Caps
- Reflowed Headers
- Replaced Ribbon Cables
- Replaced Power Cable Connector/Pins at Linear Power Supply J4/J5, and Super CPU Board J1.
The image on the screen didn't change much afterwards. It was basically the same (pic1). Troubleshooting the MCR seemed to be the next step.
A close inspection of the board stack showed that
The Video Gen board:
- looks good - no mods or fixes.
The Super CPU board:
- A couple traces had been cut & jumper wires soldered in. Behind R159 & R160 on the solder side, and next to the Analog De/Multiplexor Chip 1G (MC14053B).
- Jumpers JW2, 11, 14, and 15 have been snipped, and both JW1 & JW13 have a resistor in its place.
The Super Sound I/O board:
- Caps C104 - C111 have been snipped, as has the SIP Resistor at RM3.
- LED 1-3 are missing (they don't appear to have been installed).
Are these common mods? Or are they something you'd find on a problematic board set?
I'd like to fill in those LEDs also, but I can't find specs on them.
Here's what I've done so far:
- Replaced Caps
- Reflowed Headers
- Replaced Ribbon Cables
- Replaced Power Cable Connector/Pins at Linear Power Supply J4/J5, and Super CPU Board J1.
The image on the screen didn't change much afterwards. It was basically the same (pic1). Troubleshooting the MCR seemed to be the next step.
A close inspection of the board stack showed that
The Video Gen board:
- looks good - no mods or fixes.
The Super CPU board:
- A couple traces had been cut & jumper wires soldered in. Behind R159 & R160 on the solder side, and next to the Analog De/Multiplexor Chip 1G (MC14053B).
- Jumpers JW2, 11, 14, and 15 have been snipped, and both JW1 & JW13 have a resistor in its place.
The Super Sound I/O board:
- Caps C104 - C111 have been snipped, as has the SIP Resistor at RM3.
- LED 1-3 are missing (they don't appear to have been installed).
Are these common mods? Or are they something you'd find on a problematic board set?
I'd like to fill in those LEDs also, but I can't find specs on them.
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