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Post by edoetsch on Jun 2, 2015 13:08:11 GMT -7
Not exactly sure what that means and just wanted to check with those in the know if this sounds like a valid diagnosis. This is a repair for my Route 66.
Repair: "One the power tubes we dead, inside one of the power tube sockets had its grid resistor(this is part of the bias) broken off. This would kill a tube."
Me: "This grid resistor problem, is it common? Is there risk of the other socket having problems?"
Repair: "It looked like the guide pin on one of the tubes broke off and the resistor hangs right in its path busting it. Never saw that before so I wouldn't worry"
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Post by Maddog on Jun 2, 2015 15:23:11 GMT -7
I've seen grid resistors break from age and heat. I've never seen one break from a guide pin breaking off a tube's base. Sounds odd to me, but I guess it's possible.....
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Post by simpleton on Jun 2, 2015 15:56:01 GMT -7
I think I blew one on a Swart I had from a tube over spec....or something. Just bring a crowbar in when you get the bill and pick up the amp.
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Post by simpleton on Jun 2, 2015 15:56:38 GMT -7
Probably bad advise above .... Don't listen to that guy.
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Post by deluxetwelve on Jun 2, 2015 20:59:36 GMT -7
I've certainly had guide pins bust on those Gold Lion KT66, but the pin just sat in the socket without busting anything (ps some superglue fixed it.)
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Post by zpilot on Jun 4, 2015 23:05:52 GMT -7
I've been repairing amps for decades and I've never seen a broken grid resistor. However, if a guide pin should break off and remain in a socket and then another tube is inserted it would most likely break that resistor. It would take a considerable amount of force. I've seen a fair amount of other crazy things caused by people who don't know what they are doing though so I don't doubt that it could happen. You are lucky that the socket did not crack.
This serves as a warning to the rest of us to check when removing a tube with a guide pin that the pin has not broken off. This is mainly for amps that the tubes are inserted down instead of up (as in most combos).
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Post by edoetsch on Jun 5, 2015 8:26:42 GMT -7
I've been repairing amps for decades and I've never seen a broken grid resistor. However, if a guide pin should break off and remain in a socket and then another tube is inserted it would most likely break that resistor. It would take a considerable amount of force. I've seen a fair amount of other crazy things caused by people who don't know what they are doing though so I don't doubt that it could happen. You are lucky that the socket did not crack. This serves as a warning to the rest of us to check when removing a tube with a guide pin that the pin has not broken off. This is mainly for amps that the tubes are inserted down instead of up (as in most combos). Hmm certainly could have happened. I tried other tubes after the amp went down in case it was simply a tube problem. May have broken the resistor then.....however the original problem was something else then. We will see. He says the amp is playing beautifully now and I pick it up next week.
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Post by simpleton on Jun 5, 2015 8:46:52 GMT -7
Keep us posted
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Post by Paul (TRANE) on Jun 5, 2015 19:18:58 GMT -7
Don't ask how I know this. But, if a tube pin is off size (larger diameter) it can push the metal retainer that holds the tube pin, out the back side of the socket. At least on octal power tubes......and yes I know that from experience. Have to say I felt like an idiot. Repair was easy though and cheap enough.
Paul G.
Sent from my SM-N900V using proboards
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Post by edoetsch on Jun 10, 2015 11:02:54 GMT -7
Got it and will take it home tonight. Guy had a barely used set of 10 year old GT KT66's. These are the ones I think the Doc was putting in the amp when it originally came out. Will keep you posted.
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Post by thunderstruck(formerly doc001) on Jun 10, 2015 11:19:13 GMT -7
Got it and will take it home tonight. Guy had a barely used set of 10 year old GT KT66's. These are the ones I think the Doc was putting in the amp when it originally came out. Will keep you posted. Nice tubes for sure
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Post by simpleton on Jun 10, 2015 12:17:58 GMT -7
Got it and will take it home tonight. Guy had a barely used set of 10 year old GT KT66's. These are the ones I think the Doc was putting in the amp when it originally came out. Will keep you posted. Something to get excited about on the old hump day ....
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Post by edoetsch on Jun 11, 2015 6:39:40 GMT -7
Sounds great. I can give references for those in the Boston (Wilmington) area if you are in need of repair!
Send me PM.
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Post by zpilot on Jun 11, 2015 7:38:58 GMT -7
Good to hear. Sending an amp back to the factory for repairs is not always a good option so finding a local tech is essential. I've never had a "Z" fail, other than tubes which is to be expected at some point. However, some amps are old enough now that things like caps are going to start to go bad and there is always corrosion to deal with. That is just life with a tube amp. Some of us can do our own repairs but most can not. It's good to find one BEFORE you need it and the best way is through references from other users.
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