Vintage DS-5 repair

[worldfamousandy]

Mine is the original, came w my ‘76 series 1. I hadn’t used it in years, but when I plugged it in the other day a couple sparks and a puff of smoke came out. Fuse is still intact, so I think something shorted to ground. Who can fix this? If there are decent instructions, I’d give it a whirl myself, but I’d rather send it to someone who is good at this sort of thing. Advice?

[JimmyJ]

Andy,

Sorry to hear about your DS-5 troubles.  If I remember correctly, the originals didn't have replaceable fuses as such but had a small thermal fuse just before one leg of the transformer.  Past the transformer is a rectifier bridge and then a couple large capacitors (which do have a lifespan) to smooth out the DC output.  The circuit is not very complicated and any audio or radio repair shop should be able to figure out what happened.

Where (on the planet) are you?  Can you post any pictures of the insides?  (Remove the feet to slide out the inner chassis). Maybe we can spot the issue. 

Jimmy J

[worldfamousandy]

When I opened it up, I vaguely recall doing some work on this 25+ years ago, and maybe telling myself that this thing will need a new transformer at some point. Today, I see a somewhat sloppy in-line solder that could have easily been my handiwork as a 20-something. I'll send this to an electronics guru and get it done right. I live in Wyoming, and no such guru lives within driving distance. Any suggestions?

[keith_h]

These power supplies are pretty basic and should be easily serviced by any competent electronics technician or TV repair person . Do you have anyone near you that does electronics repair? That's where I would start.I've attached a jpeg of the schematic below.

[lbpesq]

It looks like the original thermal fuse was replaced by a regular fuse.   Have you tested the replacement fuse to see if it’s blown and/or if it’s the correct value of 1/2 amp?    How about the connection at the end of the replacement fuse that’s hidden under the electrical tape?

Bill, tgo

[JimmyJ]

OK, yes, you have a couple mods there...  The hard wired fuse is not stock.  And although you need to have something there for safety, it's such a tight space that you must be careful to heavily insulate all that so it doesn't touch the chassis.  That's looking pretty dangerous.

Also, check to make sure that the outside of the big capacitor on the right is not touching the rectifier lead.  That could make trouble.

I also don't recognize the small red wire coming from the rectifier's input terminal and going to the front panel.  I'm guessing there was a pilot light or LED added at some point but depending on what kind of light that is, it's being run from one side of the transformer's output - so 15-20VAC.  I'd think about that and maybe suggest instead an LED run from the rectifier's + and - output legs (30-40VDC) with the correct resistor.


Jimmy J