#1
Hey
Does anyone know how to check the bias on a 5150? i wanted to do the bias pot mod to it but when i opened it up i found out that the last owner had already done it. now i just want to check the bias so see where its at. i searched on google and couldnt find anything.
www.myspace.com/wearedraind
My Rig:
ESP LTD MH401NT
ESP LTD EX-400BD (two of them)
Peavey 5150
Mesa 4x12 Straightback Slant cab loaded with v30's
#2
Aren't there two test points on the back panel of the amp? You a digital multimeter to test it
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#4
Quote by htsktim91989
Aren't there two test points on the back panel of the amp? You a digital multimeter to test it


not on a 5150. they were sent out of the factory with a fixed bias which is why people do the bias mod to it so they can run the tubes hotter. you can mod it and add bias test points but i cant find out to do that
www.myspace.com/wearedraind
My Rig:
ESP LTD MH401NT
ESP LTD EX-400BD (two of them)
Peavey 5150
Mesa 4x12 Straightback Slant cab loaded with v30's
#5
Quote by 311ZOSOVHJH
get a bias probe. $30 for a single octel probe from eurotubes

the bias pot is what you turn to make the bias hotter or colder

PS: never biased a 5150


i thought about that but i know theres a way you can check it without. ive seen it in a thread before but i cant find it.

unfortunately 5150s are fixed bias with 12mV which is really cold. surprised to see that my amp already had the bias mod on it now i just want to see if i have any wiggle room to run the tubes hotter. 6l6 by the way
www.myspace.com/wearedraind
My Rig:
ESP LTD MH401NT
ESP LTD EX-400BD (two of them)
Peavey 5150
Mesa 4x12 Straightback Slant cab loaded with v30's
#7
A bias probe is so cheap these days........
1979 Gibson Les Paul Silverburst
James Tyler Variax JTV89
Schecter C1 Classic
Ibanez RG520QS
Greg Bennett Torino TR4

Mesa Boogie Dual Rectifier
GSP1101 & Pod X3 Pro
Peavey 5150 & JSX
Bugera 6262 & 333XL
Carvin V3
Spider Valve HD100
#8
i considered buying a bias probe and biasing my 5150 myself, although I could not find the test points for it, they are not right on the back like most fender or marshall amps. If someone knows where to find the test points and wants to share this info with me that would be great
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#9
Quote by handbanana
i considered buying a bias probe and biasing my 5150 myself, although I could not find the test points for it, they are not right on the back like most fender or marshall amps. If someone knows where to find the test points and wants to share this info with me that would be great


you don't need test points if you're using a bias probe.

Also, did your 5150 have a bias mod done to it? otherwise its fixed biased and cannot be adjusted to my knowledge.
1979 Gibson Les Paul Silverburst
James Tyler Variax JTV89
Schecter C1 Classic
Ibanez RG520QS
Greg Bennett Torino TR4

Mesa Boogie Dual Rectifier
GSP1101 & Pod X3 Pro
Peavey 5150 & JSX
Bugera 6262 & 333XL
Carvin V3
Spider Valve HD100
#10
There are no test points on a 5150. You have to make your own with a resistor on the cathode like 311 said, or use a bias probe. It wouldn't make any sense for them to make an amp with bias points but no bias pot, anyway.
#11
So theoretically if I bought a bias probe and a multimeter check my bias shouldn't be too hard?
Quote by alm0st a skat3r
yeah i remember when i had a good conscience. now i dont give a ****

xxx
smoke weed, drink 40's, **** titties
#12
It's quite easy to check it with those tools, but that's all you could do. You have to install a bias pot to actually bias the amp, which is more involved than using a bias probe.
#14
no my amp has never had a bias mod on it
Quote by alm0st a skat3r
yeah i remember when i had a good conscience. now i dont give a ****

xxx
smoke weed, drink 40's, **** titties
#15
Than you need that first. Any amp tech will do it for a couple of bucks; they just need to swap a resistor for a smaller one and add a trimpot.


Alternatively, I know some shops around here sell power-tube-sets selected for specific amps with unadjustable bias. I don't know any places in the States that does that (since I don't shop there), but there should be a few around. Maybe look into it.
Last edited by TheQuailman at Aug 4, 2010,