EVH 5150 III 50W - Tech help needed

[Jakem]

So a friend of mine got his 50W 5153 today and he needs some tech help. When he turned on the amp for the first time and went on to test it on channel 2, the amp made loud and scratchy noises when altering that channel's volume. He then turned off the amp and turned it on after a while and the same thing happened. He repeated that procedure once more and now the loud and scratchy noise is gone but the 2nd channel doesn't react to picking very well... a preamp tube gone bad? Anyone know the tube layout for the amp? Thx!

 

[jisham]

Email Howard Kaplan at EVH GEAR (he's an engineer there who's been posting regularly about the amp on The Gear Page). His email is hkaplan@fender.com.

 

[bsp01]

Does sound like a preamp tube. No idea about the layout, but I'd wager a guess that it would be pretty much like the 100watt. (left to right) V1,V2.... across the front, (right to left) V7/V8 (PI/FXLoop), V9-V12 (power tubes).

 

[jisham]

Does sound like a preamp tube. No idea about the layout, but I'd wager a guess that it would be pretty much like the 100watt. (left to right) V1,V2.... across the front, (right to left) V7/V8 (PI/FXLoop), V9-V12 (power tubes).

The tube layout on the 5150 iii 50 watt is different that the 100 watter. There's a tube chart inside the headshell.

 

[Jakem]

 

[hkaplan131]

Does sound like a preamp tube. No idea about the layout, but I'd wager a guess that it would be pretty much like the 100watt. (left to right) V1,V2.... across the front, (right to left) V7/V8 (PI/FXLoop), V9-V12 (power tubes).

The tube layout on the 5150 iii 50 watt is different that the 100 watter. There's a tube chart inside the headshell.

Here are the tube functions -

Preamp -

CH1/CH2 - V1B, V5A, V5B, V6A for Gain and V6B follower to drive the tone stack.

CH3 - V1A, V2A, V2B, V3A, V3B, V4A for Gain and V4B follower to drive the tone stack.

A and B are referring to tubes that have two sections.

Power Amp Section-

Phase Splitter – V9
Power Amp – V7 and V8

 

[Jakem]

Thanks for the tips, everyone! . My friend contacted the shop in Germany where he bought the amp from and they told him that he would have to take the amp to an official Fender repair center. So if he had tested new tubes in it, he would've probably lost the warranty. Therefore he sent the amp back to Germany...

 

[hkaplan131]

So a friend of mine got his 50W 5153 today and he needs some tech help. When he turned on the amp for the first time and went on to test it on channel 2, the amp made loud and scratchy noises when altering that channel's volume. He then turned off the amp and turned it on after a while and the same thing happened. He repeated that procedure once more and now the loud and scratchy noise is gone but the 2nd channel doesn't react to picking very well... a preamp tube gone bad? Anyone know the tube layout for the amp? Thx!

V1 - CH1/2 - 1/2 the tube; Ch3 1/2 the tube
V2-V4 - CH3
V5-V6 - CH1/2
V7-V8 - Power Amp tubes
V9 - PA phase splitter

There is a tube location chart on the inside left wall.

Howard Kaplan
EVH Engineering

 

[hkaplan131]

Thanks for the tips, everyone! . My friend contacted the shop in Germany where he bought the amp from and they told him that he would have to take the amp to an official Fender repair center. So if he had tested new tubes in it, he would've probably lost the warranty. Therefore he sent the amp back to Germany...

I guess I am too late. Could have helped him troubleshoot. I would have recommended swapping the preamp tubes one-by-one.

Howard Kaplan
EVH Engineering