03-13-2013, 11:54 PM
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#1 |
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Registered User
Join Date: Nov 2008
Location: SLO
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Tube amp problem (picture) I think it's a fuse
Back again,
So I was playing my amp just fine a few days ago and it worked fine, but I go to turn it on the next day and it turns on but the tubes won't even glow. It turns on but won't produce sound. I noticed it got quite hot when I played it a couple days before and thought maybe some sort of fuse went out, so I asked some questions here and took in advice and checked out my amp's innards. From what I saw, there seems to be a blown fuse but I'm not 100% positive. I took extra pictures too in case any of you notice something that I just overlooked, but I their size exceeds the limits so I don't know how to post the rest. Thanks - Joe
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09 Gibson Firebird Studio w/ vintage Seymour Duncans > Dunlop Original Crybaby Wah > Jetter Jet Drive > T.C. Electronic Nova Delay > BBE Sonic Stomp > Marshall JVM410H w/ vintage Marshall JCM800 1960 Cab Youtube Username: slojo88 |
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03-14-2013, 12:03 AM
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#2 |
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land of white cannibals
Join Date: Apr 2010
Location: deep south
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NEVER judge a fuse on how it looks. test continuity with a meter. no continuity it is blown. takes 15 seconds. if you don't have a meter buy one and probably some new fuses (a few for all of the different amp types you have IMO)
looks can fool on rare occasion, has happened to me working on drag care as well as popping fuses on the JTM45 i buily. rare, but do check.
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Sunshine in the house of flames
She loves it where she gets it But it's never felt the same Surgery, in the house of dissection When your candle burns out I'll resurrect you |
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03-14-2013, 12:17 AM
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#3 |
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Registered User
Join Date: Nov 2008
Location: SLO
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I don't have a DMM at the moment. I've been needing to buy one for a while now. Is there a way I can look up the schematics and find out what the fuse it for? Could bad tubes cause overheating?
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09 Gibson Firebird Studio w/ vintage Seymour Duncans > Dunlop Original Crybaby Wah > Jetter Jet Drive > T.C. Electronic Nova Delay > BBE Sonic Stomp > Marshall JVM410H w/ vintage Marshall JCM800 1960 Cab Youtube Username: slojo88 |
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03-14-2013, 12:18 AM
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#4 |
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Doesn't speak guitar
Join Date: Dec 2009
Location: Traffic Town LA
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It looks bad, however visually is never te best way to check. If you don't have a volt meter you can buy one for 20 bucks.
This is your jVM from the other thread right? You probably need to replace your powertubes if the fuse blows again. Last edited by R45VT : 03-14-2013 at 12:25 AM. |
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03-14-2013, 12:21 AM
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#5 |
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Registered User
Join Date: Nov 2008
Location: SLO
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Yeah, the JVM. My bad. I'm going to try and borrow a DMM if I can..... so I can spend more money on gear of course. Haha. I'll get one soon guys, I promise!!!
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09 Gibson Firebird Studio w/ vintage Seymour Duncans > Dunlop Original Crybaby Wah > Jetter Jet Drive > T.C. Electronic Nova Delay > BBE Sonic Stomp > Marshall JVM410H w/ vintage Marshall JCM800 1960 Cab Youtube Username: slojo88 |
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03-14-2013, 12:28 AM
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#6 |
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Doesn't speak guitar
Join Date: Dec 2009
Location: Traffic Town LA
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I think the JVM410 bias is at 70mv. Do you see the 3 pins for checking the bias? Each side should be set at 70mv... If I remember correctly...
If you are unsure, or uncomfortable you will need to take it to a tech. High voltages are present on tube amps and could kill... |
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03-14-2013, 12:31 AM
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#7 |
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Registered User
Join Date: Nov 2008
Location: SLO
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Just noticed this too, lookin at R81.
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09 Gibson Firebird Studio w/ vintage Seymour Duncans > Dunlop Original Crybaby Wah > Jetter Jet Drive > T.C. Electronic Nova Delay > BBE Sonic Stomp > Marshall JVM410H w/ vintage Marshall JCM800 1960 Cab Youtube Username: slojo88 |
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03-14-2013, 12:37 AM
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#8 | |
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land of white cannibals
Join Date: Apr 2010
Location: deep south
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Quote:
time to strip her down. looks like the fuze didn't pop fast enough. another note is when getting replacement fuses, there are sloblo and fast blow as well. they are not interchangeable. i have an ampeg lee jackson that burned up something, but now i don't remember where that it was and can't find it. R45vt will give you some useful tips, he helped me out in a quite few spots in the blue voodoo modding.
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Sunshine in the house of flames
She loves it where she gets it But it's never felt the same Surgery, in the house of dissection When your candle burns out I'll resurrect you |
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03-14-2013, 12:44 AM
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#9 |
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Doesn't speak guitar
Join Date: Dec 2009
Location: Traffic Town LA
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I'll look at the schematic later. The PCB looks like it got hot around the left fuse clip on 4.
If 81 is in the bias or powertube related you are going to need to take it to a tech. I'll see if I can't find a schematic later and post back up. Anything else look like it got hot? |
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03-14-2013, 12:49 AM
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#10 |
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Registered User
Join Date: Nov 2008
Location: SLO
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__________________
09 Gibson Firebird Studio w/ vintage Seymour Duncans > Dunlop Original Crybaby Wah > Jetter Jet Drive > T.C. Electronic Nova Delay > BBE Sonic Stomp > Marshall JVM410H w/ vintage Marshall JCM800 1960 Cab Youtube Username: slojo88 |
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03-14-2013, 12:51 AM
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#11 |
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Registered User
Join Date: Nov 2008
Location: SLO
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Looks connected to overheating from what I can tell.
__________________
09 Gibson Firebird Studio w/ vintage Seymour Duncans > Dunlop Original Crybaby Wah > Jetter Jet Drive > T.C. Electronic Nova Delay > BBE Sonic Stomp > Marshall JVM410H w/ vintage Marshall JCM800 1960 Cab Youtube Username: slojo88 |
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03-14-2013, 01:07 AM
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#12 |
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Doesn't speak guitar
Join Date: Dec 2009
Location: Traffic Town LA
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In that schematic its part of the HT to float the heaters by the center tap.
I would take it to a tech for repair. F4 is one of the fuses for the heaters. |
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