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Hi, I have a early SVT-2 Pro in the shop that is misbehaving. When it arrived the main problem was that it would switch into "fault" mode after 15-25 minutes of hard playing. I found a old tech bulletin #TIB003 and removed the 1n4007 diodes and uppped the resistors fro pin 4 of the power tubes. I replaced some blown 10ohm resistors on the cathodes in the monitoring circuit. Now the last time I played it it screached till I turn it off after 15 minutes playing. I have worked on many vintage SVT's but this is my first of this model. Any suggestions?
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My experience with these are bad power tubes are what causes problems and it's most likely what caused your problems with the 10 ohm resitors blowing. The Sreen resistors should be fine at their current ratings. Six 6550's are hard to keep in balance and tube wear is very sparatic in these amps. If the 10 ohmers blew I'd be wary of the TLO-72's in the bias led circuit. The amp will run on 1 tube or one on each side for testing. If the leds don't come on when the standby is off that could be a problem. If you can get a fault not to occur without power tubes that is a good start. If it trips without power tubes theres no use in putiing any in.KB -
Turned out it was the monitoring circuit. I had to replace several ICs and diodes to get it up and running again. Have to recomend staying away from the Pro and sticking to the regular SVT2.Comment
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What does exactly this bulletin #TIB003 say?I found a old tech bulletin #TIB003 and removed the 1n4007 diodes and uppped the resistors fro pin 4 of the power tubes.Comment
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What does exactly this bulletin #TIB003 say?I found a old tech bulletin #TIB003 and removed the 1n4007 diodes and uppped the resistors fro pin 4 of the power tubes.Comment
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