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Posted: 3/11/2015 12:41:38 PM EDT
[#1]
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Posted: 3/11/2015 1:45:32 PM EDT
[#2]
For parts try Angela Electronics . Steve has been doing the amp stuff a looooong time
Mouser for the caps.. replace all your electro coupling caps while your at it. Another place to peruse Ted Weber, they have a good selection of parts. I have bought from all of them with no problems, including Antique Electronics, posted above. In fact, I bought a Marshall 6m45 kit with a red tolex cab some years back from Weber.. out of the blue they sent me a replacement dog ear front panel, citing that they were not satisfied with the build quality of the one originally sent with the kit. THAT's service. |
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Posted: 3/11/2015 1:55:29 PM EDT
[#3]
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Posted: 3/12/2015 10:08:37 AM EDT
[#4]
Quote HistoryThey're one of my favorites. And other than what has been mentioned, http://www.mojotone.com, https://www.tubedepot.com, and http://www.triodeelectronics.com are other options. |
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Posted: 3/13/2015 2:38:49 AM EDT
[#5]
Awesome, thanks guys.
Here's the beginning of my project: 
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Posted: 3/13/2015 4:48:51 PM EDT
[#6]
Looks like it should be fairly easy to work on. Gonna do any mods?
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Posted: 3/13/2015 6:48:47 PM EDT
[#7]
Step 1: black knob for the Normal channel Volume pot! |
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Posted: 3/13/2015 7:48:33 PM EDT
[#8]
Quote HistoryQuoted:
Looks like it should be fairly easy to work on. Gonna do any mods? Quote HistoryQuoted:
Looks like it should be fairly easy to work on. Gonna do any mods? Not sure yet. For now the amp is practically unsafe to play, the filter caps are ruptured and need replacing first thing, then upgrade to 3-prong power cord and get rid of the death cap. Once the amp is restored and rendered safe, I'll play it for a while and see what I want to do. The bass channel is pretty dull for guitar use so it lends itself to modding. I've heard of people doing "Plexi" mods and other such things to get more gain in that channel. I just don't want to do anything irreversible. It currently has a 12AT7 for the phase inverter but I will replace that with a 12AX7 to get a little more drive out of it. It currently doesn't break up until 6-7 on the volume and that's LOUD. I would prefer to play at 3-4 on the volume with "edge-of-breakup" drive. Quoted:
Step 1: black knob for the Normal channel Volume pot! I think I may just leave it. It gives the amp character IMO. |
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Posted: 3/14/2015 4:54:11 AM EDT
[#9]
The JTM45 circuit is based on the Tweed Fender Bassman, and even though your Bassman is a Blackface, it should be pretty straightforward to turn the gain channel into a Plexi circuit.
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Posted: 3/14/2015 2:08:59 PM EDT
[#10]
Quote HistoryQuoted:
The JTM45 circuit is based on the Tweed Fender Bassman, and even though your Bassman is a Blackface, it should be pretty straightforward to turn the gain channel into a Plexi circuit. Well it has a solid state rectifier like a Marshall but the 6L6 power tubes of a Fender. I think the tone and dynamics will end up somewhere in-between. It should sound great no matter what. |
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Posted: 3/14/2015 2:41:07 PM EDT
[#11]
Deleted.
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Posted: 3/15/2015 9:00:40 PM EDT
[#12]
Quote HistoryQuoted: Well it has a solid state rectifier like a Marshall but the 6L6 power tubes of a Fender. I think the tone and dynamics will end up somewhere in-between. It should sound great no matter what. Quote HistoryQuoted: Quoted: The JTM45 circuit is based on the Tweed Fender Bassman, and even though your Bassman is a Blackface, it should be pretty straightforward to turn the gain channel into a Plexi circuit. Well it has a solid state rectifier like a Marshall but the 6L6 power tubes of a Fender. I think the tone and dynamics will end up somewhere in-between. It should sound great no matter what. |
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Posted: 3/21/2015 6:13:20 PM EDT
[#13]
Quote HistoryQuoted:
Oh, I would definitely keep the 6L6s in there too, EL-34s would hurt the cleans too much. Quote HistoryQuoted:
Quoted:
Quoted:
The JTM45 circuit is based on the Tweed Fender Bassman, and even though your Bassman is a Blackface, it should be pretty straightforward to turn the gain channel into a Plexi circuit. Well it has a solid state rectifier like a Marshall but the 6L6 power tubes of a Fender. I think the tone and dynamics will end up somewhere in-between. It should sound great no matter what. Not to mention they would draw too much current and the power transformer would probably blow. Anyways, I just completed the 3-prong power cord conversion, replaced the screen grid resistors, and replaced the Deep and Bright slider switches. Just need the filter caps and it should be GTG: 
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Posted: 3/21/2015 11:55:14 PM EDT
[#14]
Quote HistoryQuoted: Not to mention they would draw too much current and the power transformer would probably blow. Anyways, I just completed the 3-prong power cord conversion, replaced the screen grid resistors, and replaced the Deep and Bright slider switches. Just need the filter caps and it should be GTG: http://img.photobucket.com/albums/v292/Post4Free/Mobile%20Uploads/image_zpsmnskopn2.jpg Quote HistoryQuoted: Quoted: Quoted: Quoted: The JTM45 circuit is based on the Tweed Fender Bassman, and even though your Bassman is a Blackface, it should be pretty straightforward to turn the gain channel into a Plexi circuit. Well it has a solid state rectifier like a Marshall but the 6L6 power tubes of a Fender. I think the tone and dynamics will end up somewhere in-between. It should sound great no matter what. Not to mention they would draw too much current and the power transformer would probably blow. Anyways, I just completed the 3-prong power cord conversion, replaced the screen grid resistors, and replaced the Deep and Bright slider switches. Just need the filter caps and it should be GTG: http://img.photobucket.com/albums/v292/Post4Free/Mobile%20Uploads/image_zpsmnskopn2.jpg Anyway, it's looking good!  |
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Posted: 3/22/2015 12:23:14 AM EDT
[#15]
Quote HistoryQuoted:
Yes, but I assumed that went without saying. Anyway, it's looking good!
Quote HistoryQuoted:
Quoted:
Quoted:
Quoted:
Quoted:
The JTM45 circuit is based on the Tweed Fender Bassman, and even though your Bassman is a Blackface, it should be pretty straightforward to turn the gain channel into a Plexi circuit. Well it has a solid state rectifier like a Marshall but the 6L6 power tubes of a Fender. I think the tone and dynamics will end up somewhere in-between. It should sound great no matter what. Not to mention they would draw too much current and the power transformer would probably blow. Anyways, I just completed the 3-prong power cord conversion, replaced the screen grid resistors, and replaced the Deep and Bright slider switches. Just need the filter caps and it should be GTG: http://img.photobucket.com/albums/v292/Post4Free/Mobile%20Uploads/image_zpsmnskopn2.jpg Anyway, it's looking good!
Thanks. I had a problem when I powered the amp up, one of the resistors on the filter cap board shorted out and blew the fuse. All the filter caps are blown so hopefully that's what caused the resistor to fry, otherwise I'm going to be doing a lot of troubleshooting. 
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Posted: 3/23/2015 2:14:23 AM EDT
[#16]
Quote HistoryQuoted: Thanks. I had a problem when I powered the amp up, one of the resistors on the filter cap board shorted out and blew the fuse. All the filter caps are blown so hopefully that's what caused the resistor to fry, otherwise I'm going to be doing a lot of troubleshooting.  |
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Posted: 3/23/2015 4:00:56 AM EDT
[#17]
Quote HistoryQuoted:
It's probably been overdue for a cap job for a decade or two anyway.
Quote HistoryQuoted:
Quoted:
Thanks. I had a problem when I powered the amp up, one of the resistors on the filter cap board shorted out and blew the fuse. All the filter caps are blown so hopefully that's what caused the resistor to fry, otherwise I'm going to be doing a lot of troubleshooting.
Sure looks like it! Working on this Bassman really has me wanting to build an amp, so I think I may get a tweed 5F1 Champ or 5E3 Deluxe to wet my feet then build a a JTM-45. I may end up just leaving the Bassman as close to factory specs as I can and do my modding on a home brew amp. |
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Posted: 3/23/2015 2:42:49 PM EDT
[#18]
What happened was the filter cap is shorted and it drew too much current thru the ballast resistor which fried it. Electrolytic caps often go short-circuit when they fail as the two foil layers inside touch. Then you get a ton of current which causes the smoke and cooks the ballast resistors...
I have one of those blackface Bassman heads myself. I hardly ever use it - got too many other amps I like better. I have fixed a lot of vintage amps for folks in the ATL area. Used to be a hobby of mine but now I just work on a few friend's amps, and of course, my own. |
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