Seeburg DRD1 Short

So here is my situation.... I have been working on a Seeburg USC-2 & a Seeburg SPS-2. The USC-2 has been coming along, after fixing the DCC-2 & the TSA-10 (recap and board replacement, etc...), I was able to get the unit to at least scan when numbers are pressed but not pickup, which is fine, it was progress. The SPS-2 has been sitting with a newly capped DCC-4 waiting for a SHP-1 so I have not done much with that unit.

So tonight working on the USC-2 all of a sudden I heard what sounded like a solenoid trip. I found out it was the counter, and seemed to be stuck but the machine was on but not doing anything except for lights were on (I was actually cleaning & painting parts). I turned off the unit as I did not want it to fry anything, well guess what. I turned the unit on again to try and troubleshoot and the F3102 8/10A fuse blew on the Power Board in the DCC. So I disconnected everything, the black box (DTP1) the grey box (DRD1), the service switch replaced the fuse and turned the unit back on, the fuse was OK. Turned it off and continued to add pieces back, first the service switch and was able to move the mech, then the DTP1 (black box) and the fuse was still OK. I added the gray box DRD1 and POP the fuse goes. I replaced the fuse (I have a lot of them ) and disconnected the 1 cable that connects to the gray box from the DCC, leaving the 1 joint connection wire and turn the unit on, the fuse was OK. The minute I plug in the other cable (which primarily if the Blue connector on the DCC-2) the fuse Pops. So thinking it may be the Gray box, I swapped it for the one on the SPS-2 and POP, the fuse goes again.

Now if I put either Gray box in the SPS-2, the same fuse in that DCC-4 pops, so apparently I fried both my gray boxes, is this even possible? How would I troubleshoot the gray box? I took the covers off of one and could not see anything first visibly burned and testing some of the caps on there they seemed fine. Keep in mind the 1 gray box was in my SPS-2 and the machine was working fine now both gray boxes trip the same fuse in to different machines with 2 different DCC units.

Any suggestions? Not sure I want to buy another gray box and fry that one too so I need to figure out what happened.

I would assume that troubleshooting procedures of this kind would require the knowledge of an experienced technician - one who's background in electronics theory is substantially more than just "swapping out modules".
At this point, a solid background in component-level troubleshooting is mandatory, and, sorry to say, way beyond a novice's putzing and hoping.

I have an extensive background in electronics repair of 1960's & 1970's Gottlieb & Bally pinball machines, as I have been doing restorations for 20 years. No, I do not have experience with 1970's jukeboxes and their components but again am skilled with electronics and troubleshooting as I have recapped amps and receivers for my HF100r, USC-2, SPS-2 and 146 Trashcan, so I do know how to read and follow schematics. I also worked for 15 years as a technology research specialist in a high end IT infrastructure and now work in IT Security for 10 years. So I maybe a Novice in jukeboxes but not in electronics and troubleshooting.

So do you happen to have the schematic breakdown for the 2 boards in the graybox?
Are you a skilled technician that can troubleshoot and repair the 2 gray boxes I have?

Sounds like the static-sensitive devices in that module have been compromised somehow. (it must have the warning labels on it)
Either by careless handling practices, or surges due to improper connection.
I'd locate the B+ short.

Ron,
If you want that info, you will need to purchase, and read, a copy of the late Tony Millers "Black/gray box book".
Those are LSI based, units, and are often compromised, by just opening them, without proper static protection.
Yes--I have, and do repair them. Ron Rich

When I got both of these, neither had the "Warranty" paper across them but they seemed to be working prior, well atleast they were not shorting out the fuse

Ron, I did buy you're The Seeburg Microlog Jukebox Troubleshooting Guide, just has not been delivered yet. I will look into getting Tony's book.
How much to troubleshoot & repair one?

Hi Ron,
Thanks--but why didn't you buy it from me directly ?
See PM for price quotes, as I do not post "stuff" like that--
Ron Rich

Well I have been able to make 1 DRD-1 out of 2.
So I narrowed the problem to the 70-311285-A receiver board. There is a direct short when testing across C28, I replaced C25, 28 & 29 because they were reading to high as well but did not fix the issue. I will hold onto this one and continue to try and find the short, but atleast I have one working one. The other problem was when I took apart the other DRD-1 the 311033-2 Tormat board was cracked, looks like someone took it apart and jammed the cover back on and broke the board, not much can be done to fix that.