Posted: Sun Jul 26, 2009 4:34 am
Go up to 100uf.Pens wrote:Fuck. I can't find 68uF 450V axial caps.
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Posted: Mon Jul 27, 2009 8:52 pm
Yeah I know, but those are expensive as fuck. I found radial 68uF 450V caps, just not axial, and they are 1/3rd the price of the 100uF axials. I'm still shopping.DuoSonicBoy wrote:Go up to 100uf.Pens wrote:Fuck. I can't find 68uF 450V axial caps.
Posted: Mon Jul 27, 2009 9:47 pm
The whole industry has started to move away from axial - it's a shame.
I assume yr not buying the fancy German "guitar amp" caps that are like $6, right?
I assume yr not buying the fancy German "guitar amp" caps that are like $6, right?
Posted: Mon Jul 27, 2009 10:31 pm
No I was looking at Mouser and the Axial 100uF 450V caps were $13 a pop. Compared to $3 per for 68uF 450V radial. FUCK!DuoSonicBoy wrote:The whole industry has started to move away from axial - it's a shame.
I assume yr not buying the fancy German "guitar amp" caps that are like $6, right?
Posted: Mon Jul 27, 2009 11:03 pm
100uf 450v axial caps:
Weber has them, house brand, for $4.25
Antique Electronic Supply (www.tubesandmore.com) has Illinois for $4.23
Tube Depot has Illinois for $4.95 and fancy F&T German for $8.95
Triode Electronics has 80uf for $4.95 and 100uf for &7.95. They also have some of the clamp-mount caps it looks like you might need.
Weber has them, house brand, for $4.25
Antique Electronic Supply (www.tubesandmore.com) has Illinois for $4.23
Tube Depot has Illinois for $4.95 and fancy F&T German for $8.95
Triode Electronics has 80uf for $4.95 and 100uf for &7.95. They also have some of the clamp-mount caps it looks like you might need.
Posted: Sun Aug 02, 2009 6:52 pm
Okay, sorted that shit. Next issue:
Here's the schem for this amp. The problem now is the cap to ground right before the fuse on that scheme, it's listed as 0.005uF but on mine it's 0.003uF 400V. I cannot locate a replacement for this. Now honestly. I'm not really even sure what the fuck it's doing there, so I can't say if increasing it's value is okay. Mouser only has 1uF 450V as the closest thing. Anyone know what the fuck this cap is for here?
Here's the schem for this amp. The problem now is the cap to ground right before the fuse on that scheme, it's listed as 0.005uF but on mine it's 0.003uF 400V. I cannot locate a replacement for this. Now honestly. I'm not really even sure what the fuck it's doing there, so I can't say if increasing it's value is okay. Mouser only has 1uF 450V as the closest thing. Anyone know what the fuck this cap is for here?
Posted: Sun Aug 02, 2009 8:29 pm
Usually, those are there to decrease radio interference. It should by non-polarized ceramic, which wouldn't go bad.
You only need to change out the polarized electrolytic caps, since they are the only ones that can dry out.
You only need to change out the polarized electrolytic caps, since they are the only ones that can dry out.
Posted: Mon Aug 03, 2009 12:09 pm
This is a polarized oil cap. It looks like all the others. And it is definitely polarized. Not worrying about that one then. Thanks.DuoSonicBoy wrote:Usually, those are there to decrease radio interference. It should by non-polarized ceramic, which wouldn't go bad.
You only need to change out the polarized electrolytic caps, since they are the only ones that can dry out.
Posted: Fri Aug 07, 2009 3:55 am
FYUCK IS IT FIXED?!!!
Posted: Fri Aug 07, 2009 12:57 pm
Waiting for caps.
Posted: Fri Aug 28, 2009 12:25 pm
FUUUUUUUUU.
Okay, it took me a while to get the damn PCB out to replace those caps, then I stalled for a while with job interviews and shit needing to go to the hardware store for some O-Ring clips since the new "can" cap was a screw-type and not tabs like the old one, but I finished the cap job and put this thing back together.
It is still "quiet".
However, I think the issue is a power tube bias one. I had it half-together when I tested it, and I noticed when playing that the power tubes actually flashed BLUE when I would hit a rawk chord, and it was very saturated. The "quiet" ness appears to be over saturation, as the decay of a chord gets louder.
I think my power tubes are biased hot.
Now, I have to either A) find time to study the damn schematic to determine how to rebias this, install a pot instead of a fixed resistor, and rebias this damn thing when I've never done this before. B) Take it to a fucking professional who has time to do this and I don't, but they'll charge me a fuckload to rebias it.
Okay, it took me a while to get the damn PCB out to replace those caps, then I stalled for a while with job interviews and shit needing to go to the hardware store for some O-Ring clips since the new "can" cap was a screw-type and not tabs like the old one, but I finished the cap job and put this thing back together.
It is still "quiet".
However, I think the issue is a power tube bias one. I had it half-together when I tested it, and I noticed when playing that the power tubes actually flashed BLUE when I would hit a rawk chord, and it was very saturated. The "quiet" ness appears to be over saturation, as the decay of a chord gets louder.
I think my power tubes are biased hot.
Now, I have to either A) find time to study the damn schematic to determine how to rebias this, install a pot instead of a fixed resistor, and rebias this damn thing when I've never done this before. B) Take it to a fucking professional who has time to do this and I don't, but they'll charge me a fuckload to rebias it.
Posted: Tue Sep 01, 2009 12:17 pm
Mike, I know you've done bias jobs before, any thoughts on which resistor I need to replace with a trimpot so I can work the bias on this thing?
Posted: Tue Sep 01, 2009 12:35 pm
Afraid not, I've only biased amps that already have a bias pot in place so I only know the theory and not how to insert one.
Thegearpage.net has some knowledgable people, as does offsetguitars.com - try Brad (his username is lots of theta symbols on offset.com)
Thegearpage.net has some knowledgable people, as does offsetguitars.com - try Brad (his username is lots of theta symbols on offset.com)
Posted: Wed Sep 02, 2009 5:42 pm
Thanks. I'll have to skim some schematics and see where they are on other 6L6 amps, and try to deduce where one goes on this one.
Have a show Friday and I need to write 4 songs by then, so I won't be able to get to this til probably next week.
Have a show Friday and I need to write 4 songs by then, so I won't be able to get to this til probably next week.
Posted: Fri Sep 11, 2009 1:51 pm
Okay based on research I need to replace the 6.2k and 33k resistors with a pot and fixed ~15k 2W resistor to ground to accomplish this. However, I'm also looking into installing a pre-amp out jack at this point since I'll be digging around into this. My thought is I can possibly get a tube poweramp kit to do ~100W power amp.
Will keep y'all posted.
Will keep y'all posted.
Posted: Fri Sep 11, 2009 3:35 pm
Correction, it appears the only thing to do is install a powersink and a "line out box" to do that, so no internal shit necessary. Imma get on the bias pot.
I very badly want to build the power stage of a Bassman 100 as a separate unit now and run the "line out" into it. Actually, I wonder if I could just install a switch-jack inserted between the pre-power stages...wait no, that won't work. I need some way to not hook up a speaker cab but not fry my OT. Wonder if you could lift the output from the power tubes/shunt to ground safely then pull the signal from the wiper of the volume pot?
I very badly want to build the power stage of a Bassman 100 as a separate unit now and run the "line out" into it. Actually, I wonder if I could just install a switch-jack inserted between the pre-power stages...wait no, that won't work. I need some way to not hook up a speaker cab but not fry my OT. Wonder if you could lift the output from the power tubes/shunt to ground safely then pull the signal from the wiper of the volume pot?