Magnavox R2R fix

[hermitcrab]

this is the machine I mounted a small variac in the cabinet of the Imperial to keep the speed somewhat close ... only problem with that plan was the motor would stall in FF or REW under a 5 or 10 volt drop that it was running at...so since I had a day off , I tore it out and replaced the motor run cap... which is rated at .7uf ... when I measured the ESR is was reading just under 4 ohms!.... I did not have a .7 so I used one of my 1uf fan motor caps that measured .2 ohms... much better ... the new cap installed and the machine now plays at the correct speed without help of a variac ... didn't know a bad motor cap would speed up the motor... they usually slow down as the motor heats up... learn something new every day..

[William]

Interesting story, Elton. I think I bring my R to R over and let you do your magic. As I have mentioned before, it's sick and I'm scared to tear into it.

Bill

[hermitcrab]

Bill, these are all getting to the age where they need recapping. It doesn't matter what the brand is either , My Sony 366 just started acting up, one channel weak , but it has not been recapped yet other than the motor cap ... the Sony 250 that I totally recapped a year ago is now exhibiting static in one channel either one of the new caps was a dud or now it has a leaky transistor ...

[William]

It's always something, Elton, but that is what makes it fun. Right?

Bill

[TC Chris]

How about some general advice on motor-run caps? I've got a couple 3-motor R to R machines with lazy takeup and rewind motors, and that aged caps may be the issue.

Sources, specs, etc?

Chris Campbell

[hermitcrab]

Just as every other application try to match the capacitance and voltage ratings of the cap you want to replace. Digikey and mouser are good sources , but shipping is crazy for a single cap. I usually buy ceiling fan caps from home improvement stores if they have the right capacitance in stock. Lazy motors are a sign of bad caps

[TC Chris]

I was wondering if motor-run caps have special characteristics. Somewhere I had read about using them for some other application that benefited from some characteristic that start caps had.

Chris Campbell