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Author Topic: My Marshall has blown again  (Read 4083 times)

bucketshred

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My Marshall has blown again
« on: December 12, 2010, 09:38:34 PM »
Sorry, just venting, I only found out when I had an audition yesterday :(

Luckily I got through though :D

Paddy

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JacksonRR

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Re: My Marshall has blown again
« Reply #1 on: December 13, 2010, 12:16:26 AM »
Symptoms?

Telerocker

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Re: My Marshall has blown again
« Reply #2 on: December 13, 2010, 12:33:00 AM »
Oh that's bad. Bad tubes? Overheating?
Mules, VHII, Crawler, MM's, IT's, BG50's.

Ratrod

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Re: My Marshall has blown again
« Reply #3 on: December 13, 2010, 10:19:06 AM »
Symptoms?

It says 'Marshall' on the front.
BKP user since 2004: early 7K Blackguard 50

bucketshred

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Re: My Marshall has blown again
« Reply #4 on: December 13, 2010, 11:12:15 AM »
Think the OT has blown on the amp and the cab doesn't work with anything :( going to test it all next weekend with a friend though.

I've had a TSL and a JCM800 now which have all blown on a yearly basis. Bugger that! I'm getting it fixed, flogging it and getting something reliable. Any suggestions?

Paddy
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tekbow

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Re: My Marshall has blown again
« Reply #5 on: December 13, 2010, 01:49:27 PM »
JCA50 or 100 :)

blackstar? seeing as you like marshall?

JacksonRR

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Re: My Marshall has blown again
« Reply #6 on: December 13, 2010, 01:58:50 PM »
Well if the cab doesn't work with anything, that may be a good place to start. Do you have another cab to test the amp with? Have you opened the cab to check for loose connections or tested the tip and ring connections of the cabinet jack for continuity? You have a multimeter on hand?


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sgmypod

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Re: My Marshall has blown again
« Reply #7 on: December 13, 2010, 04:06:02 PM »
Or and lovely orange brick built amps, well I know the english one seem to be
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bucketshred

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Re: My Marshall has blown again
« Reply #8 on: December 13, 2010, 04:07:43 PM »
Tried my head with another cab and tried my cab with another head. Nothing. Bugger :(

Right, I guess I'm amp shopping in the new year. Always wanted an Orange, guess I can get one now :)

Paddy
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JacksonRR

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Re: My Marshall has blown again
« Reply #9 on: December 13, 2010, 04:20:34 PM »
You didn't you use the same speaker cable by any chance?

JacksonRR

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Re: My Marshall has blown again
« Reply #10 on: December 13, 2010, 04:27:50 PM »
Can you check whether or not the preamp is putting out signal or if the power amp section is working? If you have an effects loop, you can you plug straight in the return hooked up to the cab that's known to be working. Help separate some problems. Have you taken the chassis out of the case to look for problems? Bubbly caps, burnt resistors, browned molex connectors.... Are the tubes lighting up? Any sound whatsoever? Crackles, pops, buzzing....

Twinfan

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Re: My Marshall has blown again
« Reply #11 on: December 13, 2010, 05:05:09 PM »
You didn't you use the same speaker cable by any chance?

Good point!

Do all the valves fire up and glow?  Are all the fuses OK?

JacksonRR

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Re: My Marshall has blown again
« Reply #12 on: December 13, 2010, 05:21:38 PM »
   Most times when an output tranny or power tranny go, they will actually smell burnt to a degree. Put your sniffer on em, dude.

Dmoney

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Re: My Marshall has blown again
« Reply #13 on: December 13, 2010, 06:05:36 PM »
Tried my head with another cab and tried my cab with another head. Nothing. Bugger :(

Right, I guess I'm amp shopping in the new year. Always wanted an Orange, guess I can get one now :)

Paddy

If you open your cab you should be able to test if the speakers are ok by using a cheap multimeter.
the speakers, depending on how they are wired, might cause a problem with fault finding.
but a good speaker has a + to - resistance similar to the impedance of the speaker. I think i used to get 6 or 7ohms from an 8ohm speaker. The different reading is just because impedance is frequency dependent and not like standard passive resistance. I think!

that would you should be able to find what has blown, or if it is a wiring issue.

as for the head.
As for the amp... plugging in the FX return is usually a good way to test only the power amp. might be loud. depends if a master vol is pre or post loop.
if you get sounds there then the issue is in the preamp. If you get nothing still... then it is the power amp.

You can check transformers using a multimeter. checking resistance on the primary of the OT by measuring right across the winds, and then each side to the common. each side to the common should be equal i think. If you have a short or really weird reading it is a sign your OT is messed up. It isn't a very accurate or 'be all, end all' test and it is never safe to poke around in amps, but it is something I read about once when I needed to check one.


bucketshred

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Re: My Marshall has blown again
« Reply #14 on: December 13, 2010, 06:09:06 PM »
You didn't you use the same speaker cable by any chance?

Good point!

Do all the valves fire up and glow?  Are all the fuses OK?

None of the valves glow at all.

Paddy
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