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Post by "Z" Steve on Apr 27, 2019 20:01:53 GMT -7
I went to plug in my ASAT straight into the 8 after restringing it, only to hear barely audible distorted notes. I did the usual rule out possible issues by tapping each tube, changing one tube at a time, using DeOxit on the tubes and effects loop inputs. I even tried a different speaker, guitar, and cable - no luck. Is there anything I missed before sending it in for service? I jam with some friends on Monday nights and I always use the triode setting (pushing it pretty hard) - but no change if I switch to pentode.
Thanks!
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Post by purpletele on Apr 27, 2019 20:25:46 GMT -7
I went to plug in my ASAT straight into the 8 after restringing it, only to hear barely audible distorted notes. I did the usual rule out possible issues by tapping each tube, changing one tube at a time, using DeOxit on the tubes and effects loop inputs. I even tried a different speaker, guitar, and cable - no luck. Is there anything I missed before sending it in for service? I jam with some friends on Monday nights and I always use the triode setting (pushing it pretty hard) - but no change if I switch to pentode. Thanks! Steve, that sure sounds like a bad power tube or the rectifier going bad. The next time you play it there might be an event. No go on the new power tube?
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Post by "Z" Steve on Apr 27, 2019 21:10:53 GMT -7
I changed out both power and recto - same issue. It does seem tube related because the harder I hit a string the note acts like it trying to break free and escape. I will repeat the process tomorrow and maybe the DeOxit will have done it's job or a tube will fail. Glad I have my Cure!
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Post by purpletele on Apr 27, 2019 23:20:50 GMT -7
I changed out both power and recto - same issue. It does seem tube related because the harder I hit a string the note acts like it trying to break free and escape. I will repeat the process tomorrow and maybe the DeOxit will have done it's job or a tube will fail. Glad I have my Cure! That almost sounds like a failing resistor, like a grid resistor that you see mounted on the tube socket. You have a great tech though, he'll probably serve you lunch while he fixes your issue. I'd like to hear the results when your done with your lunch
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Post by premiumplus (Dave) on Apr 28, 2019 10:06:33 GMT -7
Next step would be to take a known good 12AX7 and go down the line, substituting it at each preamp position.
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Post by purpletele on Apr 28, 2019 10:23:19 GMT -7
Next step would be to take a known good 12AX7 and go down the line, substituting it at each preamp position. I am pretty sure he did that Dave.
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Post by Chilly Gibbons (Todd T.) on Apr 28, 2019 10:39:48 GMT -7
Did you clean all of the jacks to include the input?
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Post by Chilly Gibbons (Todd T.) on Apr 28, 2019 10:40:09 GMT -7
And speaker jacks?
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Post by Chilly Gibbons (Todd T.) on Apr 28, 2019 10:40:56 GMT -7
And, try it without the eq bypass pedal plugged in.
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Post by premiumplus (Dave) on Apr 28, 2019 11:00:20 GMT -7
Next step would be to take a known good 12AX7 and go down the line, substituting it at each preamp position. I am pretty sure he did that Dave. Yeah, my duh... Did you put a cable between the effects in/out jack? That'll cause what you're hearing. I see that he cleaned the jacks with deoxit but unless you get in there and clean the contacts that close when the plug is removed, it won't always help. Try plugging a cable between the in/out jacks.
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Post by "Z" Steve on Apr 28, 2019 12:16:05 GMT -7
Before I make a decision re service I will take out the chassis and clean the input jacks inside as well. I did use the DeOxit on all inputs (except reverb RCA's). Thanks for all the comments - great family we have here!
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Post by Chilly Gibbons (Todd T.) on Apr 28, 2019 17:53:01 GMT -7
I changed out both power and recto - same issue. It does seem tube related because the harder I hit a string the note acts like it trying to break free and escape. I will repeat the process tomorrow and maybe the DeOxit will have done it's job or a tube will fail. Glad I have my Cure! This makes me suspect something in the input stage. If interpreted correctly, it sounds like when you hit the strings hard and generate maximum voltage from the pickup, it almost works - as if it is trying to overcome sort of impedance on its way to the preamp. Also, tighten down all of the jacks and pots, or ensure they are already tight.
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Post by zpilot on Apr 28, 2019 18:00:30 GMT -7
Separate troubleshooting the amp before and after the effects loop. Run a cable from the "send" jack to a known good amp input. Then run a line level signal into the "return" jack. That will at least tell you in which half of the circuit your problem is located.
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Post by "Z" Steve on Apr 29, 2019 9:48:49 GMT -7
Update:
I pulled the chassis out, sprayed and cleaned the sockets and 1'4" jacks on the inside, rechecked all bolts. I looked at the circuits & resistors around the sockets and didn't see any obvious (like something leaked or was fried). But, when I put it all back together I found that V3 made some popping noise when I was inserting it. When I did the rest of the tubes and fired it up there was no sound at all - dead quiet. I replaced the tube in V3 but no change. Replaced fuse for the heck of it - no change. I haven't tried zpilot's suggestion yet, but I think it will require "professional" help. Thanks again for the suggestions. I will update when it gets resolved.
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Post by DRZ on Apr 29, 2019 11:39:32 GMT -7
Update: I pulled the chassis out, sprayed and cleaned the sockets and 1'4" jacks on the inside, rechecked all bolts. I looked at the circuits & resistors around the sockets and didn't see any obvious (like something leaked or was fried). But, when I put it all back together I found that V3 made some popping noise when I was inserting it. When I did the rest of the tubes and fired it up there was no sound at all - dead quiet. I replaced the tube in V3 but no change. Replaced fuse for the heck of it - no change. I haven't tried zpilot's suggestion yet, but I think it will require "professional" help. Thanks again for the suggestions. I will update when it gets resolved. Boy I wish I could suggest something Steve. It still seems that the Rectifier is lunched. I'll need to see that one on the bench I suppose. Z
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Post by "Z" Steve on Apr 29, 2019 12:33:11 GMT -7
Thank you Doc. I just pulled the chassis and took some gut shots. Excuse my untrained knowledge re components, but if you are looking straight down st the chassis with the 5 large "M80's" (filter caps?), to the immediate left of them are a small black 25uf then a larger "smoked" component that looks burnt underneath. Also, right above the 1st 2 large caps is another component that looks toast on the underside. I cant post pics to the forum anymore but I would be happy to share them via phone or email.
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Post by "Z" Steve on Apr 29, 2019 14:47:35 GMT -7
I sent my gut shots to Z Headquarters and rec'd a reply from the Good Doctor. It seems I have a fried bias resistor, by-pass cap, and screen resistor due to an output tube failure. This is the first ever issue I have ever had with any of my Z amplifiers in 11 years, and as is most typical it is tube related. Time to schedule a Dr. appointment.
Thanks again for all the advice!
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Post by Deleted on Apr 29, 2019 14:59:28 GMT -7
The peanut gallery appreciates the follow up info too @"Z" Steve!
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Post by purpletele on Apr 29, 2019 16:06:25 GMT -7
I sent my gut shots to Z Headquarters and rec'd a reply from the Good Doctor. It seems I have a fried bias resistor, by-pass cap, and screen resistor due to an output tube failure. This is the first ever issue I have ever had with any of my Z amplifiers in 11 years, and as is most typical it is tube related. Time to schedule a Dr. appointment. Thanks again for all the advice! Steve, Can you send me a photo, I'd like to see that. bvallis@vallisinc.com
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Post by "Z" Steve on Apr 29, 2019 16:32:57 GMT -7
I will get it to you when I get home Brian within the hour!
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Post by "Z" Steve on May 5, 2019 9:43:32 GMT -7
Maz 8 sent to the Z shop on Friday. I opted out of the updates for two reasons. 1-finances, 2 - I've been more than happy with it the way it is. I'm looking forward to getting it back all repaired and tuned up.
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Post by "Z" Steve on Jun 5, 2019 15:25:16 GMT -7
I received my Maz 8 back last night. The bad components were replaced and then gone over by Don. I can't say enough about the bomb proof packing that was done on my chassis. After reconnecting everything and running it through a few paces it sounds like my old friend again! I may rethink pummeling the thing on Triode mode though - time to click that toggle to 8 watts once in a while.
Thank you Doc, Don, and to all the advice given. Wonderful gift we have here.
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Post by Dan F"i"fe on Jun 5, 2019 16:38:47 GMT -7
There's nothing worse that sending your amp into the Doc.... lol
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Post by Jaguarguy (Mike) on Jun 5, 2019 22:17:58 GMT -7
There's nothing worse that sending your amp into the Doc.... lol My problem is that I visit the shop to bring my amp directly to Doc - unfortunately I always see something I've got to have! Seriously, the service provided by Doc and company is amazing!
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