Update on the Blackout that I'm struggling to get into attract mode: I'm pretty new to the hobby, but not entirely clueless... I've spent a good bit of time reading the various troubleshooting guides for Williams sys3-7 and I'm not getting anywhere, so asking for some help...
This blackout is a bit Frankensteined; its got a system 4 MPU and the power supply from one of the games that still had the -300v line for priming the displays. My understanding is that that shouldn't matter, but it has made things more than a bit confusing having to look at 3 different sets of schematics and trying to cross reference everything and make sure that the PS is sending out the voltages that the other boards actually want to see.
So I've double checked all that and it all looks good from what I can tell.
Weird stuff: The Solenoid line from the transformer to the PS reads 40v (it should be 28 according to the schematic). The guy who owned it before me said he was always blowing the 2.5A solenoid fuses.... Seems like this may be why, right?
Q1: why is that high?
Q2: is it a problem
Q3: how do I get it down to 28v?
The +16v Lamp lines are also a bit high. They test at 20v... That doesn't seem like a big deal, but I thought I'd mention it.
The Bridge rectifiers that feed these lines test at 15VAC and 29VAC. The schematics want them at 13.5 and 25.5.
Q4: are those within normal tolerances? Or do I need to look into this...
Things I've tried: All voltages powering the boards look good (haven't tested anything beyond power getting to the boards, don't know how!)
I toasted a ROM, so I got new ones and replaced the SCANBE sockets with machined pin ones, Same for the two 6810 RAM chips. I tried that because I was getting the 'lower LED stays on' error code pretty consistently and I read that meant there was a read/write error on those chips... Having replaced the chips and sockets i still get the same error. So...
Q5: What else could cause that error? Or what else should I be looking at?
I haven't done the 40 pin interconnect yet, but it tests good on all pins for continuity. I have parts to replace it in the mail...
Q6: is there any way it could pass continuity testing across the pins and still be causing problems?
Q7: How to I go about isolating the problem that is keeping the machine from booting into attract mode?
Thanks very much for any help you can offer!