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Problem with the FX preamp tube slot 5150


Iron Lotus

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...Yeah so I have a little issue. The amp has been cutting out.. dropping in volume with some blowing scratchy sounds

thrown in there, and sometimes a nice POP when flipping it back off to standby. I figured pre amp tubes..

 

Tested my tubes... Theyre good.

I thumped each pre amp tube while it was fully on...

And then wiggled each one ever so slightly...

Its DEFINITELY the V3 effects loop cathode follower slot...

I swapped out tubes, just to be sure and repeated that test...

Different tube, but same spot.. the one right next to the Phase Inverter.

Its not the FX jacks themselves, I tried the patch thing.. theyre fine.

 

So it cut out started blowing wind sound, I pushed on that certain

tube,(v3) wiggled it a little and it stopped. Wiggled it some more.. it

started again... The contacts seem to be tight... Ive been inside

the amp and do well with all the mods/soldering/etc etc... Never messed

with anything on the preamp board. My next step would be pull the chassis

and check for a cracked solder joint from pushing/pulling out tubes

so much trying to find the right tube combination.. maybe cracked a joint.

 

What do you guys think before I have to get up in this things ass tomorrow...?

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I have this exact same problem right now. It started when I was swapping/trying out a bunch of preamp tube combinations so I'm 100% certain it's a cracked solder joint or 2, just been too lazy to crack it open and fix it :lol: I hate the way that board is mounted... Flexes like crazy when removing/installing tubes.

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I have this exact same problem right now. It started when I was swapping/trying out a bunch of preamp tube combinations so I'm 100% certain it's a cracked solder joint or 2, just been too lazy to crack it open and fix it
:lol:
I hate the way that board is mounted... Flexes like crazy when removing/installing tubes.

 

Yeah its not supported very well at all for pre amp tube exploring.

Mine has been doing it for about 2 months I knew at some point

I was gonna have to eventually work on the damn thing

so of course I was just lyykkkk :facepalm: ...Im also thinking

of a way to add additional support somehow, stop excess flexing.

My amp always be flexin on em. :p

 

 

 

 

 

Guess I'll fix her up in the next 2-3 days.:cop:

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I used to have a FX loop issue with my 5150

I just left a jack plugged in the pedal slot


problem fixed

 

You didnt even read my original post. I said it was the effects loop tube slot... not the effects loop.

And I also said I tested the effects loop jacks, just to be sure that wasnt the problem. Does anybody read or

do you guys just pretty much want paint pictures to illustrate shit every time? LIke if its more than 2 sentences

mothafuckas start fallin outta their chairs n shit, I dont get it. But thanks for the reply at any rate. :thu:

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Does anybody read or do you guys just pretty much want paint pictures to illustrate {censored} every time? LIke if its more than 2 sentences

motha{censored}as start fallin outta their chairs n {censored}, I dont get it.

 

 

Pretty much ^this

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The tube joints were fine, its the .022 cap thats above that fx tube slot that was a little loose, and also you can tell

it was exposed to alot more heat due to its position. I think I need to just replace the cap instead of re-solder it.

 

Also adding a 10pf silver mica cap between pins 6 and 7 on the v5 slot (middle tube)..... Takes away alot of FIZZ.

Will probably go ahead and upgrade my other 2 screen grid resistors like I did the last time on the power

tube board.... A couple went, so I replaced them with 470ohm 5watters, need to get the 2 that werent bad, and upgrade them while IM at it.

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The tube joints were fine, its the .022 cap thats above that fx tube slot that was a little loose, and also you can tell

it was exposed to alot more heat due to its position. I think I need to just replace the cap instead of re-solder it.


Also adding a 10pf silver mica cap between pins 6 and 7 on the v5 slot (middle tube)..... Takes away alot of FIZZ. Will probably go ahead and upgrade my other 2 screen grid resistors like I did the last time on the power tube board.... A couple went, so I replaced them with 470ohm 5watters, need to get the 2 that werent bad, and upgrade them while IM at it.

 

Hmmm, apparently on the screen grid resistor thing... I had already upgraded them all...:facepalm: Theyre already 470 ohm 5w 5%. Its been a while since I did that:freak: My power tube board screws instead of rivets... its a 2002 5150.

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