Fisher 250

[copterske2]

Hello all, I found this receiver last year at curbside. It required merely a new fuse to be up and running. Quite pristine inside and it works/ sounds very nice. The only problem is the tuning mechanism is very tight, such that turning the knob has no effect. I can only get it to move by directly manipulating the pulley shown at the bottom of the first pic and even then with difficulty. I have checked out some other threads that recommend application of penetrating oil, but also warn not to get it on or around the fins. In this assembly the fins are very close to the gears et al. Would it be safe to try that on this unit? To be honest it doesn't necessarily feel like a lubrication problem, it feels and sounds more like mechanism that has too high of a gear ratio...of course that doesn't make sense as I never heard of downshifting a tuner!
Thanks as always, Steve

 

[MrTube]

You may need to use some thin lube to lube the tuning capacitor. Be careful to keep the blades clean and dry. I would start with some 3 in 1 or even WD40 (to see if it frees it up) Don't spray it at it, spray it on a screw driver tip and let it drip onto the edges by the bearings\bushings.
if you use 3 in one it might be fine, but if you use WD40 be sure to put some actual oil in it after you confirm that it did indeed free it.

 

[copterske2]

Cool, worked like a charm. Thanks...

 

[copterske2]

Now that that is working I have another question. There is a noticeable difference in the signal level of the left and right channels. Obviously with a 40 year old unit some recapping is in order. I did notice some corrosion on the power caps. Am I correct in guessing that replacing these would correct the above problem?

 

[ryuuoh]

If you've cleaned the controls, and there is no obvious noise, I'd try poking around with a scope to see where the fault occurs. Recapping probably should be done, looking at some of those caps~