fix for a dead 70-77 gm am fm radio
 

70-77 am fm stereos use two delco modules for the preamp circuitry. The DM48. This radio had a bad one and as you may or may not know this part is not in reproduction. I reverse engineered the bad one and hand wired my own and it works perfect. This one is a prototype and I have also made this into a circuit board that will be a direct replacement for dead modules.

That is so awesome.
You should post an ad for said service in the classified.
I have a 65 am fm that had the big power transistor (D-501 IIRC) that was bad. I replaced it and it works great.
I was able to find a NOS transistor on E bay.
Not to many guys that restore old car radios.Kudos

I am finishing the circiut layout today and I should have working modules in house in a couple of week and the new module will be superior to the original by design. I am also remaking the larger DM28 found on plenty of early 70's delco am/fm stereo radios and even the casette player. I will post some pics later today. The availability of these parts should get alot of radios working again.

pic of my new module
 

Here it is. She's a beauty. Contact me if you need one. It should be available in a few weeks. Fully tested and plug and play.

I need this!!
 

I've been searching on line for DM48 chips for weeks... finally happened across this thread. I think this is still the only solution? It's 10 years later, you'd think there'd be options.

Check with S&M Electro-Tech aka Turnswitch.

They were super nice and sent me a used module.

http://forums.maxperformanceinc.com/...ighlight=radio

The owner passed away last year. I think they still sell speakers but have passed on the repair operations to someone near the the repair facility.

Oh that is unfortunate sad news. If it was Greg, he was an exceptional person and I'm sure will be missed by all he helped.

dm48
 

Hey j69shep,
I’m new to this forum. Been working on Delco radios for 15 years. Self taught in repairing the Delco 2700 and 2000 series. Every now and then I run across a part not being reproduced. This DM48 module is a hard one to find. I sure can appreciate some reverse engineering and someone taking the time to map this one out.
Any chance of getting a couple of these completed DM-48 modules? I’ve been working on a ‘75 Delco Stereo. I am sure I have a bad one.

Unfortunately, j69shep hasn't been to the site for a couple years, so you may not get a reply.

j69shep's contact info is on his Public Profile under vistor messages