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    Smoked a 7199

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    batman7349

    Posts : 14
    Join date : 2014-12-08

    Smoked a 7199

    Post by batman7349 on Tue Dec 23, 2014 10:47 pm

    I found a factory wired ST 70 in a man cave store and just could not pass it up. Checked her out and re-soldered a couple of joints. Pulled the tubes and used a dim bulb setup to bring her back to life. I have her on a bucking transformer. So far so good. Put the EL34's back in and checked the voltage between pins 2 & 7 they run 6.0 @ 110 volts and 6.5 volts on 117 volts. So I decided to run on 117. Put the rectifier tube back in set the bias @ 1.56. Then put the 7199's back in. Left channel dead quiet, but right channel was crackling. I noticed there was no filament glow on the right tube and it is grey on the top. So question are there some voltages I need to check on the driver board? I have a set of adapters and a pair of 6GH8 tubes on order. I don't want to smoke one them right off the bat.

    HifiGuy

    Posts : 6
    Join date : 2010-09-09
    Location : South Carolina

    Re: Smoked a 7199

    Post by HifiGuy on Sat Dec 27, 2014 5:47 pm

    Hey, Since it's looking like the experts ain't here today, I'll give 'er a try. First off, check the filament wiring. If the left channel passes a signal I would try pulling the tube that glows from the dead quiet left channel and plug it into the right channel that crackles. If all is well you have a bad 7199. If that don't get it going I'd wait around for someone else to chime in.

    A factory wired ST 70 is a real good find. If you have never experienced "tube sound", you are in for a real treat.

    Happy new year!

    Chip

    batman7349

    Posts : 14
    Join date : 2014-12-08

    Re: Smoked a 7199

    Post by batman7349 on Sun Dec 28, 2014 10:21 am

    Thanks Chip. I measured the filament at 6.5 so I went ahead and put the remaining good 7199 in the right side and all went well. Still waiting on the adapters and 6GH8 tubes to arrive so I have not had a chance to listen to it yet. Also just finished de-humming my Little Bear T10 riaa phono stage, so hopefully sometime before the end of 2014 I'll be able to give it all a listen!

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