Fixing Scratchy Knobs and Burned out Bulbs

The first thing that I did was flip the amp over to take out the screws to get inside.

Once I was inside thankfully the lights that I needed to replace were right on top in the front of the amp, you can see there are 4 bulbs stuck in the back of the vu meter and held in with rubber sleeves.

All I had to do was carefully remove the bulbs, and then clip the wires on the old bulb and solder in the new bulbs, I opted to just replace the bulbs with regular bulbs rather than update to LED’s because I like the way they look better, but if they burn out too quickly then next time I probably will just go with LED’s.

Once the VU Meter bulbs where done I had to move on the the bulb in the radio tuner indicator.

Thankfully I didn’t have to mess around with it too much, particularly this crazy string setup, but I just had to remove the two screws in the top and then clip out the old bulb and solder in the new one.

At this point I decided it was a good idea to clean up the inside out the amplifier. Whenever you go into an old piece of electronics it is a good idea to get out as much dust as you can, since electronics don’t like heat it makes sense to remove the warm fuzzy blanket of dust covering everything.

You could use caned air, or an air compressor to blow everything out, but I like to just use these micro bristle vacuum attachments to suck up all of the dust.

Now the last thing that I need to do is spray some DeoxIT (#notsponsored) into the potentiometers to clean them out and get rid of the scratches. Fortunately even though it was pretty tricky to film I could get the straw to all the pots to spray them without taking anything apart, and then turn the knob back and forth to work in the DeoxIT (#notsponsored).

And with that everything that I needed to do to this amp is done.

I haven’t been inside too many vintage receivers to know if these things are common but I thought there were a couple of things that were interesting enough to be worth pointing out.

First how there is a switch on the front of the amp for selecting phono 1 or 2. But it is actually hooked up to this drive shaft that runs to the back of the amp where it turns the actual electrical switch. I would guess this helps keep noise down in the phono preamp by not having the wiring come all the way to the front of the amp.

The other funny thing is just how crazy this string setup is for the tuner, it comes from this heavy flywheel here on the back of the knob. It comes down and back and wraps around the actual tuner, then it comes back up and surrounds some pulleys and ties into the indicator, and then ties back around into a full loop.

Also this plastic jointed arm whose job it is to hold the wire to the indicator light bulb is just the most delightful little thing.

Now all that was left was to put the amp back together and it is all ready to go.

I can appreciate that maybe you don’t have this exact amplifier but these two quick repairs are common things that need to be done on most old HIFI equipment.

So don’t be afraid to get in there and fix up your old electronics to work like new.


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