Trying to fix an old radio

[skippyelwell]

I p/u this Grundig AM/FM shortwave radio from the 70's and I'm not sure how to proceed.
Has anyone found a method of repair to fix a break like this?

 

[Flange]

Find the cause of the over current and then just solder a jumper wire in. You could drill a hole at each end to feed the wire thru. I've never bothered.

 

[Elektrishun]

@Flange beat me to it.🙂

Agree, don't attempt to power it "ON" unless you know it's fixed. I built a Dim Bulb Tester for checking old electronics where their health is unknown (let's you power it ON while reducing the risk of damage if something is seriously wrong).

 

[phaxtris]

carefully sand off some of the varnish off back where the trace is good on both ends and solder in a wire to replace the trace

alternatively you could follow the trace all the way back to the component on each end and solder a wire to completely replace the trace, a solid 18 or 20g would be more that adequate

 

[Elektrishun]

alternatively you could follow the trace all the way back to the component on each end and solder a wire to completely replace the trace

That's the method I prefer.

Edit: And be careful!

 

[Elektrishun]

Last bit of advice from a hobbyist electronics guy - usually when a trace looks like that something very serious happened. The trace blows apart like a fuse. Soldering in a jumper is likely just the beginning of the repairs.

 

[slow-poke]

The placement of some traces can be important, especially in a RF design, I think you are better off placing a wire over the burnt area. Obviously the fault needs to be determined and corrected first.

 

[phaxtris]

The placement of some traces can be important, especially in a RF design, I think you are better off placing a wire over the burnt area. Obviously the fault needs to be determined and corrected first.

i would agree, when i have done this i bend up a piece of wire to follow the existing trace

 

[skippyelwell]

Thank you Gentleman, it's funny that both fuses were good.

 

[Elektrishun]

Thank you Gentleman, it's funny that both fuses were good.

A family member brought over a failed computer power supply about 3 weeks ago. He said he was nearby when it "sparked". After I cleaned all the dust bunnies out I checked it over. Everything looked good and then I turned over one of the circuit boards and noticed a tiny scorch mark on one of the traces. Not nearly as dramatic looking as the image of your radio but it opened the trace. Fuse was good, too.

I don't know how often it happens but I have heard of really old fuses failing to work when expected. As well, sometimes a slow blow fuse gets installed by accident where a fast or very fast fuse should have been.