Model TH-4. Here's my dilemma, folks. This is one of those very compact models that makes working on them such a challenge. But worse,it has the crumbling rubber insulation. Nearly every wire has bare spots and touching anything only makes it worse. The radio has only a very soft hum when on. I figure that I am going to have to replace the insulation on every wire as I work on it. Any advice on how to proceed? Any tips or tricks from someone who has worked on one of these? Not looking for advice on what might be wrong, but more how to cope with the limited space to work and the fact that every wire I touch is going to need insulation. I was thinking of using shrink tubing. Mark from Kalamazoo

Just a note on replacing those crumbling wires...

~ Clip the end of the wire from it's attaching point -- leaving a little tail of wire for attaching the new wire to.

~ Cut a piece of new wire to approx. proper length and tack-solder one end of it to the loose end of the old wire.

~ Clip the other still attached end of the old wire... again, leave a little tail at the connection point.

~ Now, use the old wire to pull the new wire through the chassis... Doing so will retain the proper routing for the new wire... In some cases this is important.

~ Clip the new wire free from the old one and solder it in place, using the little wire tails to attach to.

~ This procedure will enable you to match the original wiring perfectly.

Dennis

I like (and have long used) Dennis' described method. It minimizes the disturbance to existing solder joints and, if done carefully, is cosmetically nice, as well.

The note about retaining the original wire routing is very important for some sets, particularly in the high-gain audio amp stages- and deviating from the factory wire routing often results in sets having an aggravating hum.

I'll add that I just used this approach to partially rewire a 1937 RCA Model 811K. I use the "tail" approach when one or both wire terminal points have several "fanout" components. When a wire is the only thing on a terminal (as on a bandswitch contact, for example) I will just unsolder and replace the wire without clipping/soldering to a "tail".

Besides a small sidecutter, I find that it is helpful to use a surgical needleholder to tease out and hold wires. These are available at vet supply stores (or well-stocked farm stores) and are rather inexpensive.

Sorry, no shortcuts, tips for this dilemma. I would just replace each lead, one at a time as needed, with regular hook-up wire, not shrink tube..but that's up to you. If any crumbly leads are routed through or near the chassis, replace them, as there's a good chance they will short to the chassis some day as the covering crumbles off.
The main problem is as you try to move wires to get to others to replace, you crumble a couple more..especially in a chassis that was laid out with a tight fit for the components..it's a no win situation.

:Model TH-4. Here's my dilemma, folks. This is one of those very compact models that makes working on them such a challenge. But worse,it has the crumbling rubber insulation. Nearly every wire has bare spots and touching anything only makes it worse. The radio has only a very soft hum when on. I figure that I am going to have to replace the insulation on every wire as I work on it. Any advice on how to proceed? Any tips or tricks from someone who has worked on one of these? Not looking for advice on what might be wrong, but more how to cope with the limited space to work and the fact that every wire I touch is going to need insulation. I was thinking of using shrink tubing. Mark from Kalamazoo

I have had success in using a tube of clear silicon sealant, squirting it in and around all the wiring using a small screw driver to lift and move the wire slightly to make sure of no shorts and getting the sealant in between the wires. Give 24 hour cure time. This has worked well when everything was too tight to try to change the wiring.
C Harris

::Model TH-4. Here's my dilemma, folks. This is one of those very compact models that makes working on them such a challenge. But worse,it has the crumbling rubber insulation. Nearly every wire has bare spots and touching anything only makes it worse. The radio has only a very soft hum when on. I figure that I am going to have to replace the insulation on every wire as I work on it. Any advice on how to proceed? Any tips or tricks from someone who has worked on one of these? Not looking for advice on what might be wrong, but more how to cope with the limited space to work and the fact that every wire I touch is going to need insulation. I was thinking of using shrink tubing. Mark from Kalamazoo
:
:I have had success in using a tube of clear silicon sealant, squirting it in and around all the wiring using a small screw driver to lift and move the wire slightly to make sure of no shorts and getting the sealant in between the wires. Give 24 hour cure time. This has worked well when everything was too tight to try to change the wiring.
:C Harris
:
:
Thanks guys! These are just the sort of things I wanted to know. It's such a small radio, but I feel overwhelmed just looking at it. I will post a follow up when I have a chance to spend some time on it. Mark from Kalamazoo

:::Model TH-4. Here's my dilemma, folks. This is one of those very compact models that makes working on them such a challenge. But worse,it has the crumbling rubber insulation. Nearly every wire has bare spots and touching anything only makes it worse. The radio has only a very soft hum when on. I figure that I am going to have to replace the insulation on every wire as I work on it. Any advice on how to proceed? Any tips or tricks from someone who has worked on one of these? Not looking for advice on what might be wrong, but more how to cope with the limited space to work and the fact that every wire I touch is going to need insulation. I was thinking of using shrink tubing. Mark from Kalamazoo
::
::I have had success in using a tube of clear silicon sealant, squirting it in and around all the wiring using a small screw driver to lift and move the wire slightly to make sure of no shorts and getting the sealant in between the wires. Give 24 hour cure time. This has worked well when everything was too tight to try to change the wiring.
::C Harris
::
::
:Thanks guys! These are just the sort of things I wanted to know. It's such a small radio, but I feel overwhelmed just looking at it. I will post a follow up when I have a chance to spend some time on it. Mark from Kalamazoo
:
It's a pain when the wires crumble inside the IF cans. That can cause a short circuit and with B+ voltage you could burn up the IF coils. You would need to remove and disassemble the IF cans and replace the wires and or use heat shrink and follow the same color codes on the replacement wires. The oscillator coil if there was a short in the wires it could burn up. Then your done for unless you have a replacement (junk spare parts one). Some radios IF were built not using 455kH.