Discussion: The relationship between the Fosgate PR-250 and the Pioneer AD-360

I recently acquired a Pioneer AD-360 from the late Jim Fosgates estate. At first, I was hopeful that he threw some secret sauce in this one and i'd get to be the only one to enjoy that. Turns out he didn't. In fact, it didn't even work. So my next guess was a friend left it with him for repair because 'My buddy Jim knows amps' is probably how the rationale went.

So I went looking for a schematic. But I was too cheap to buy the service manual. Then I started looking up part numbers. The part numbers led to a thread here

The drawing note on the PR-250 schematic led me down a rabbit hole as not only was I able to use the PR-250 schematic to service my amp, it bears the 'GM160' stamp!


The drawing note:

fosgate-20-copped.png


The board stamp on my AD-360:

D360-GM160.jpg



At this point i'm just MADE of questions. Both of these amplifiers were released around the same time. It's sitting in Jim's house. One board is referenced in another's drawing. They're both 'Made in the USA' which is not common for Pioneer electronics of the era.


What was the relationship between Jim Fosgate and this product?

Did Jim OEM the AD-360 for Pioneer?

Did Pioneer License the design from Fosgate?

Did Pioneer OEM the PR-250 for Jim and Jim added the processing in house?

Was the 'GM160' a build house design both Pioneer and Fosgate custom tailored for their models?

Another interesting note: I have 2 of these amplifiers. Jim's model has no solder mask and the unit bears no serial number or warranty sticker but my other model does!
 
Last edited:
  • Like
Reactions: 1 user
I recall long ago the story that went sorta like... the Brand NEW Company, PIONEER of AMERICA was founded and soon thereafter they introduced the entire line of new Pioneer products into the American market, Craig/Pioneer dissolved and Craig became it's own entity. Lots of GROWTH in the Autosound world in 77'... By 78 Pioneer needed an amplifier offering that could compare with the American High Powered offerings available at the time and it was decided that Fosgate Electronics would build an amplifier under the PIONEER brand name. I believe the GM-160 labeling on the PCB was later used for the GM-120 etc. Not exactly a big seller but an entry into the market it became. PIONEER still to this day building great autosound products. Left CRAIG in the dust, thats for sure. I Sold LOTS of Craig at Muntz and Pioneer at AA Sound Systems here in Honolulu Hawaii. LONG ago... I have a AD-360 here right now all taken apart and it had really bad capacitor issues. Cap read RESISTOR on my tester. Real bad. I swapped out all electrolytics and now its showing signs of life... well... No popping or crackling noises from the speakers so seems the power source went from switching OFF and ON to now, it stays ON... blinking stopped and the BULB is dark, low current pull now when ON. I use a Test Light probe to do the current sense. WAITING now for the Service Manual for this thing. Theres a CHIP, FE133-7931, its an 8 pin chip... op amp?... Cant find anything online so thats kinda where i am at this juncture. Will see how this one goes. It's TIME for me to start repairing my FOSGATE gear it appears. Ugggggg....... Will keep in touch here with progress reports and cries for help.... BDBD/2023.
 
  • Like
Reactions: 1 user
NE5538 is the IC chip number. The chip reads FE133-7931 so yeah I can find the IC chip now Thank you. I really need to sit down and force myself to read and learn how this whole operation works I think. I turned this amp on thinking it was ok but as it turned on I heard a crackle and smoke... GREAT, turned it off immediately. It made my current limiting bulb light up real bright so.... on to investigation. Now that I have the schematic I can better understand the system operation. MIGHT actually find the problem... in 3 months.... LOL. THANKS moxysoft!!!! BDBD/2023
 
Yeah... Current Sensing they called it. I use a 12 volt light bulb/probe. In the old days there were these toggle switches that were illuminated and ya could use the light in them to trigger these amps too.... switch ON it lights up and turns on the amp system. Turning on MORE THAN ONE of these systems.... got tricky thus switches. Memories of a time. There were others that had current sensing circuits. BDBD/2023
 
My AD-360 PCB is a tan color, not green like in the image above. Looks like a OLD Fosgate PCB, certain features are present but others not. I will take some pictures for comparison sake. BDBD/2023
 

Attachments

  • IMG_20231216_230449821_HDR.jpg
    IMG_20231216_230449821_HDR.jpg
    436.5 KB · Views: 41
  • IMG_20231216_230502783_HDR.jpg
    IMG_20231216_230502783_HDR.jpg
    527.9 KB · Views: 43
  • IMG_20231216_230527796_HDR.jpg
    IMG_20231216_230527796_HDR.jpg
    564.5 KB · Views: 41
  • IMG_20231216_230656946_HDR.jpg
    IMG_20231216_230656946_HDR.jpg
    627.4 KB · Views: 42
  • IMG_20231216_230706911_HDR.jpg
    IMG_20231216_230706911_HDR.jpg
    453.2 KB · Views: 39
  • IMG_20231216_230713575_HDR.jpg
    IMG_20231216_230713575_HDR.jpg
    523.1 KB · Views: 37
  • IMG_20231216_230720192_HDR.jpg
    IMG_20231216_230720192_HDR.jpg
    652.9 KB · Views: 40
  • IMG_20231216_230751647.jpg
    IMG_20231216_230751647.jpg
    409.8 KB · Views: 42
  • IMG_20231216_230805607.jpg
    IMG_20231216_230805607.jpg
    416 KB · Views: 31
  • IMG_20231216_230810156.jpg
    IMG_20231216_230810156.jpg
    516 KB · Views: 34
  • IMG_20231216_230849134.jpg
    IMG_20231216_230849134.jpg
    245.2 KB · Views: 39
  • IMG_20231216_230854887.jpg
    IMG_20231216_230854887.jpg
    235.1 KB · Views: 39
  • Like
Reactions: 1 user
I recall long ago the story that went sorta like... the Brand NEW Company, PIONEER of AMERICA was founded and soon thereafter they introduced the entire line of new Pioneer products into the American market, Craig/Pioneer dissolved and Craig became it's own entity. Lots of GROWTH in the Autosound world in 77'... By 78 Pioneer needed an amplifier offering that could compare with the American High Powered offerings available at the time and it was decided that Fosgate Electronics would build an amplifier under the PIONEER brand name. I believe the GM-160 labeling on the PCB was later used for the GM-120 etc. Not exactly a big seller but an entry into the market it became. PIONEER still to this day building great autosound products. Left CRAIG in the dust, thats for sure. I Sold LOTS of Craig at Muntz and Pioneer at AA Sound Systems here in Honolulu Hawaii. LONG ago... I have a AD-360 here right now all taken apart and it had really bad capacitor issues. Cap read RESISTOR on my tester. Real bad. I swapped out all electrolytics and now its showing signs of life... well... No popping or crackling noises from the speakers so seems the power source went from switching OFF and ON to now, it stays ON... blinking stopped and the BULB is dark, low current pull now when ON. I use a Test Light probe to do the current sense. WAITING now for the Service Manual for this thing. Theres a CHIP, FE133-7931, its an 8 pin chip... op amp?... Cant find anything online so thats kinda where i am at this juncture. Will see how this one goes. It's TIME for me to start repairing my FOSGATE gear it appears. Ugggggg....... Will keep in touch here with progress reports and cries for help.... BDBD/2023.

Thanks for the info. Do you have a source for this? Please keep the thread relevant and start a separate repair thread for the repair. Thanks.