Thanks, HBP!
When I began running my "we buy tube stuff" ad, this was literally the prototypical type of situation I was imagining. I happen to live in an area where a remarkable number of folks have lived in the same homes for 35+ years. Of course I always mention that I'm into musical instruments; haven't gotten the $125 '55 Strat yet....but a neighbor DID give my niece a brown 1960 Fender Concert that is bigger than she is!
And please don't guitar-ize this amp; it really deserves to live life reproducing wonderful music.
No worries, wouldn't be prudent!
The striped Sprague caps have a reputation among radio restorers as being universally leaky. That may not be the case in your amp, but I have read an extraordinary number of posts on a restoration forum where an untold number of scopes, test equipment and radios have been fixed by simply replacing every striped cap in the entire unit. They are willing to do that because after finding a handful that are leaky, they know that the others will fail after a short additional period of time.
Yes, I have heard the same and would probably shotgun those if I wanted to operate. The issue is whether *I* should embark upon the rehab (the amp, not me!) because, at least in my feeble mind, the kind of fetishist who want this may want PIO caps, or polywhatthehell caps, or turbo-fletcher caps, and maybe it's a better bet just to offer it unmolested.
I don't have to tell you that keep the smoke-glass KT66's seperate for sale is a smart idea.
I'm think I'm just going to test them and confirm they are of decent strength.
And you may want to double-check the circuit against FYL's posted schematic. The first-stage plate and cathode resistor values on the schematic seem reversed (470k where 47k should be, and vice-versa).
There are a number of sort of interesting aspects to the schematic. You know, as examiners of many schematics, we see that mirror-image structure of a typical push-pull stage driven by one or two preamp stages and they kind of look the same after a while until one acquires higher level knowledge. I've been reading about Williamson's and triode amps and etc etc, and absorbing as I can. I *DID* notice some oddities; the HUGE cathode resistor on the first stage; the feed from the heater winding to the cathodes of the KT66's...
What I can tell you is that there was a "500", a "500A", a C500, a 550C, and perhaps one more variant. with rather modest differences...choke size(s), B+ turn-on relay, rectifier tube choice, 5U4 vs 5V4, I think they went to 6L6GA after a while....and other stuff that is either trivial or world-shaking depending upon one's fetish level. You can see from the pix that the one FYL posted has a monster choke betwixt the OT & PT, leaving no room for above-chassis electrolytics, whereas mine has a Twin-Reverb sized choke & two can electro's.
The GREAT thing about this is that I don't have to do ANYTHING about it right now, as I am swamped with family issues at the moment.
Topic: SWEET! Garage sale buy (Read 8360 times)