I've been working on a guy's DE Star Trek which has multiple problems. The first thing was a weird looking Duracell battery had exploded all over the place and battery acid was everywhere. The guy called me because the pin had recently stopped working and he wanted it fixed, naturally. From the extent of the damage, I recommended buying a new MPU and PPB board. I looked the machine over and didn't find any other problems. When the boards came in, I changed out both boards and to increase the probability of the game working, I went ahead and dropped in a new Power Supply board. I turned the game on, but it did not boot up. I had solid red lights on all boards, but no blinking LED on the MPU. I checked all of the TPs and got good voltage on the TPs for the Power Supply, but not the MPU, or PPB board. The MPU +5 volts checked good, but the +28 volts was reading .04 volts. The 28+ volts TP on the PPB read 72.2volts and the 50+ vdc TO read 76.5 volts. I took all of the connectors off of the MPU, except for CN17 and powered up, but the MPU did not boot and all I got was a solid red LED on the +5V and the PIA. The blank did not blink.
All new Rottendog boards (MPU, PPB, and Power Supply).
Any help would be greatly appreciated.

One more thing. When I turn the game on, I get "Scott here" and there is nothing on the display. No fuses blown.

As I explained, the battery corrosion "explosion" had corrupted too much of board for it to boot. I did try and power up the game as it was and I was getting nothing on the MPU. Yes, I checked both of those fuses and they are good. Shouldn't the MPU boot, if it is isolated and not connected to anything else?

I was getting good voltage on the +5 of the MPU, but not the 28+ vdc. I am not that good with schematics, so are you indicating that the lack of voltage on the +28vdc comes from those fuses? Where does the power come from before that point? The transformer? The guy said the game was playing and just stopped, so I naturally was thinking fuses from the beginning, so I checked all of the ones that were not replaced with the new ones on the new boards.

It will have to be later in the week, as the guy has limited availability.

All voltages were checked using the grounding point on the new boards. The boards did not include ROMs, so I replaced the old ones. I visually inspected the ROMs and brushed the legs off before inserting them into the new boards. I did isolate the MPU and had no blinking LED and there was a very decreased power reading coming from the +28 vdc test point.

Used the old ROMs. Would these hamper the voltage input into the MPU? Pardon my ignorance!

Yes. That was the first thing I accomplished after taking it out of the bag.

That sounds very logical; I will order some ROMs and report back.
Thank you very much for the assistance!

I am still waiting on the ROMs for the CPU, but I keep thinking about the incredibly high readings on the test points of the PPB. Any ideas?

This is a Rotten dog PPB. The 28vdc test point was reading 72vdc and the 50vdc was reading 76vdc.

I will check those areas that you mentioned. I will probably go back to the guy's house on Saturday. I will report back then. Thanks for the help!

I received the ROMs and they did nothing to help the board boot. I will be checking those areas that you mentioned tomorrow. I have two machines to work on at the same place (STNG + DE Star Trek), so I had to move on to STNG.
The most difficult part of this is having limited skills and having so many issues (of the re-import type) to deal with, not to mention the guy does not have internet (or wi-fi), so I can't access information while I am working. I also don't have the "phone-a-friend" option!
Thanks for the help!