Hey guys I have a JTM 60 combo here with low volume otherwise sounds and functions fine.
I have cleaned all the pots, switches and tube sockets. Tested tubes, checked voltages here they are.
(V1 12ax7) (V2 12ax7) (V3 12ax7) (V4 12ax7)
1 172 190 328 249
2 169 30
3 1.4 1.4 172 44
4 -3.6 -3.6 -3.6 -3.6
5 -3.6 -3.6 -3.6 -3.6
6 198 160 169
7 28
8 1.6 2.1 1.5 44
9 3.6 3.6 3.6 3.6
(V5 EL34) (V6 EL34)
1
2
3 484 484
4 476 476
5 -36 -38
6
7
8
Any ideas?
B
JTM60 1-12" combo low volume issue
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bastardbus
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- Location: Toledo, Ohio
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Stevem
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Re: JTM60 1-12" combo low volume issue
If the amp has effects loop in and out jacks poke a plug in and out of each 5 to 8 times and see if the signal level comes back up to normal.
Did you swap preamp tubes around to see if it changes the issue or better or worse?
Did you swap preamp tubes around to see if it changes the issue or better or worse?
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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bastardbus
- Posts: 55
- Joined: Tue Mar 29, 2011 6:22 am
- Location: Toledo, Ohio
Re: JTM60 1-12" combo low volume issue
Yup did that like 20 times. Left that jumpers in place and indeed you can tell the jacks seem to be are working fine but still low volume. I also cleaned all the jacks and pots with CRC then deoxit. Do these jacks just need cleaning or can they go completely BAD?Stevem wrote:If the amp has effects loop in and out jacks poke a plug in and out of each 5 to 8 times and see if the signal level comes back up to normal.
Did you swap preamp tubes around to see if it changes the issue or better or worse?
Swapped pre amp tubes all over and tested them all as well and were fine. Even swapped in new tubes in pre amp section.
I used the effects loop send and ran the pre amp into a hot rod deville and she sounded great. So pretty sure the pre amp section is good. I think it is somewhere in the output section. I tried sending the pre amp of the deville into the return of the Marshall and NOTHING...silent. BUT if I jumper the Marshall send to return it works fine.
BTW looks like the forum screwed up my voltage chart I made. I will re do that...
Re: JTM60 1-12" combo low volume issue
I suggest deoxit ALL the ribbon cable connectors.
I have a 212 model. It made a difference.
Good luck,
Denny
I have a 212 model. It made a difference.
Good luck,
Denny
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bastardbus
- Posts: 55
- Joined: Tue Mar 29, 2011 6:22 am
- Location: Toledo, Ohio
Re: JTM60 1-12" combo low volume issue
did that too, thanks though.
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Stevem
- Posts: 5144
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: JTM60 1-12" combo low volume issue
can you re post the voltage test out and a schematic ?
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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CarolinaGearHead
- Posts: 5
- Joined: Wed Jun 04, 2014 10:20 pm
Re: JTM60 1-12" combo low volume issue
Maybe bad solder joints? I've got a JTM60 and love it. Good luck and keep us posted.Greg