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Dman - I hope you can help me.My Anthem Amp 1 blew a Svet EL34 last night while I was checking the bias!
Do the Svets automatically take out a few resistors or is it possible that I can just replace the Svet tube with a new one (or a new matched pair for the channel). After the tube blew the amp seems DOA, will not power up at all.
Does anyone have a schematic for this board or know which resistors typically go with a tube failure? I would much rather replace the tubes and a few resistors than ship this HEAVY amp all the way across North America for repairs.
Many thanks in advance.
Follow Ups:
Well, looks like the job got done wihtout me gettin' into it. I know quite a bit about the Amp-1, but a LOT more about the Power series stuff ( in particular the Power 2). I don't have ANY schematcis for any SFI or anthem products- I just knew/know how to build them and test'em on the Audioprecision tester at SFI! Kind of an idiot savant if you will (everybody love self-depreciating humour, no?)
Glad you got it figured out.
Cheers, not cheese
Dman
My experience is, it will have blown the line fuse and most likely the bias resistor that goes with the blown tube. Pull the fuse & check it for continuity.Resistor replacement is pretty easy, if you're good enough with a soldering iron. I don't have the value on me, but perhaps another member does...
It would be interesting if someone has determined WHY this amp will not tolerate Svet/JJ EL34s; the Sovteks seem to be the only ones that'll live. I've heard speculation that it's a heat problem related to the power tubes being horizontal; don't know if that's true. Makes some sense, though.
Regards,
Kevin
Hey Kevin! How in the hell have you been? What sort of things have you been working on?You hit the nail on the head regarding the Svetlana's not liking being horizontal. Various posts over the years talk about the same heat issues when used that way.
The previous owner of my Amp1 had troubles with the Svetlana's and when I got the amp it needed a bias resistor replaced. If you've ever used a soldering iron it is a pretty damn simple thing to do. The designers were nice enough to put the bias resistors at the top of the circuit board so you don't even have to disassemble anything.
The only other trouble with the amp was when a Tesla/JJ tube blew. Replaced the AC fuse and put Sovtek/EH's in it and the amp came up fine. No hassles with the bias resistors. The EH's have since not caused a bit of trouble.After reading many posts here at the asylum I had biased the Tesla/JJ's at about .45 rather than .40. They sounded better but boy did they put out heat! I'm guessing that pushing them killed 'em.
Long one short, been running the EH's between .35 and .40 and they just keep going. The EH's also sound significantly better than the older/ordinary Sovtek's (that also never quit).
Hi, Barry:
what is the resistor values which u need to replace to accommodate the Svet's tubes ? thanks in advance.
Here is the (very prompt) response I got from SF tech support:"Any shorted EL34, not just Svetlana, will take out cathode resistors - acting as a fuse is their purpose. They're the brown ones beside each test point, and they're metal film, 10 ohm, 2 to 3 watt. If one of them is blown, replace it along with both tubes in that channel.
Electro-Harmonix are fine, but set the bias to 250 - 300 mV (anything
in between is fine as long as all four as set the same)."Thanks to everyone for the help on this!
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