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-   -   still trying to troubleshoot my amp (http://www.ultimate-guitar.com/forum/showthread.php?t=1565971)

psychokiller99 10-02-2012 05:21 PM

still trying to troubleshoot my amp
 
Hello again. I made a thread about my amp a few days ago. You can read it here.

http://www.ultimate-guitar.com/foru...d.php?t=1565065

if you are feeling lazy: my amp pooped out during a show. The symptoms are a loss of volume (about 80%) and a thin, slightly distorted tone on both channels. My volume only gets louder when I turn my master volume up to 3. After that it only gets more distorted.

Anyhow, I haven't taken it to a tech because a) I don't have money for that and b) I don't have confidence in the techs in the area based on past experiences. That aside, I think I've been able to further narrow down my problem.

As suggested in my previous thread I went ahead and cleaned up all the pots and all of the i/o jacks to see if one of them was just really dirty. I also re cleaned my tube sockets. I noticed that even though I had already tried retensioning the sockets, the tubes were still slipping out pretty easy. So I went and got a dental pick and tried retensioning them again. I then turned my amp on and it was back. I was getting my regular tone and volume, but when I tried turning it up past 9 o'clock I heard a faint pop and my volume and tone plummeted. So I'm stuck at point A again.

what do you guys think? It sounds like a have a bad potentiometer, but i'm not sure. How could I go about checking with a multimeter? Thanks for your help.

Hou-Tex 10-02-2012 06:11 PM

I just googled this.

http://www.ehow.com/how_5995013_che...entiometer.html

R45VT 10-02-2012 08:01 PM

I doubt its one of the pots... however it could be. Dont make new threads as its hard to follow what you have done. Just find your old(search bar) and bump it. That way we all the details.

I know you replaced some of the tubes correct?

Update this thread with all that you have done so you can get a better answer. Garbage in/garbage out.

psychokiller99 10-06-2012 01:40 AM

hey guys sorry for the late reply. I've been away from my computer for a few days. Anyhow, I've done all of the basic maintenance work. I cleaned all of the pots, jacks, and sockets. I've also retensioned the sockets and replaced all of power and pre amp tubes. I've used my entire set up with a different head and had no problems, so the problem definitely is with my amp.

I don't get any extra noise - no humming, no scratchy pot sounds, nothing like that. If i leave my amp along for a week or more I can turn it on and everything seems like its back to normal, but as soon as I turn the volume past three is when it goes to hell. Thanks for any ideas you guys might have, but I think I might just take it in to a tech pretty soon.

Cathbard 10-06-2012 01:44 AM

From what you are saying - it's the socket. Have another go at retensioning it but I'm afraid you may have to bite the bullet and replace it. Could be a tube too. If it was mine I'd try new tubes and if that failed I'd stick in new sockets.

R45VT 10-06-2012 01:17 PM

Have you changed the fuses in case you have a volt drop across it? It's a cheap test. Just make sure to replace with the same rating a speed of blowing.

All connections internally look ok? Nothin looks overheated? Anything else you want to tell us?

Edit: also when the concern is present did you tap on the tunes to listen for a pop from a bad connection? (tap on tube)

psychokiller99 10-06-2012 01:59 PM

Quote:
Originally Posted by Cathbard
From what you are saying - it's the socket. Have another go at retensioning it but I'm afraid you may have to bite the bullet and replace it. Could be a tube too. If it was mine I'd try new tubes and if that failed I'd stick in new sockets.


That sucks, but I have had my amp for about 4 years (bought it brand new) so I guess it's not surprising. I'll look around on the internet to see what I can do about the sockets, short of taking my amp in for replacements.

Quote:
Have you changed the fuses in case you have a volt drop across it? It's a cheap test. Just make sure to replace with the same rating a speed of blowing.

All connections internally look ok? Nothin looks overheated? Anything else you want to tell us?

Edit: also when the concern is present did you tap on the tunes to listen for a pop from a bad connection? (tap on tube)


I'll replace the fuse and inspect the rest of the board today. Yes, I tapped on the tubes and I didn't get any popping or crackling. I appreciate you guys keeping up with this thread. Hopefully, you guys can help me diagnose the problem before I take it to the shop. Will update later.

Robbgnarly 10-06-2012 02:03 PM

have you put new powertubes in it yet?

R45VT 10-06-2012 02:24 PM

Quote:
Originally Posted by Robbgnarly
have you put new powertubes in it yet?


He says he replaced all.

If one shit out before being replaced it could have damaged something. I'd be looking at solder joints and overheated resistors.


TS- did the concer change after replacing the tubes or is it exactly the same?

psychokiller99 10-06-2012 03:09 PM

No, there was no change in my amps behavior after I changed the tubes. I think I may have found my problem though. There is a resistor by each socket that has caught my attention. They both look like they are fried - the PCB underneath them is very dark brown. I can't tell what the value is to one of them - all of the marking look the same color. I know this sounds very vague, but I'll get some pics up soon.

psychokiller99 10-06-2012 03:16 PM

Quote:
Originally Posted by R45VT
He says he replaced all.

If one shit out before being replaced it could have damaged something. I'd be looking at solder joints and overheated resistors.


TS- did the concer change after replacing the tubes or is it exactly the same?



looks like you are probably right about overheated resistors.

http://imgur.com/a/H6V4g

R89 and R90 are the ones I am looking at.

R45VT 10-06-2012 03:16 PM

please do. Are they the 5w resistors?

Good find :cheers:

R45VT 10-06-2012 03:18 PM

Well that sucks. Take some good photos of the wiring and then pull the PCB to inspect further. It's fixable. Probably a tube took a shit and overheated them.

Also post what you amp is again. I
Might have the schematic saved.

psychokiller99 10-06-2012 03:23 PM

Ok. I'll just be a few minutes. This amp is a pain in the ass to pull apart. I should probably drain the caps right about now, but I can't get to them without shocking myself. I have a Traynor YCV50 blue.

R45VT 10-06-2012 03:38 PM

Well I don't have the schem for that amp... I thought it was 6505.

Only now did I notice it in your sig. I am ******ed. :)

psychokiller99 10-06-2012 03:53 PM

Quote:
Originally Posted by R45VT
Well I don't have the schem for that amp... I thought it was 6505.

Only now did I notice it in your sig. I am ******ed. :)




No worries. I don't think it's a very popular amp. Here are some more pics. 5 and 7 are pictures of a pair of resistors where the PCB looked similar to the ones by the sockets, but not as bad. The solder joints look okay though. Also, is there any significance to the brownish spots along the traces?

http://imgur.com/a/f3bLr#6

R45VT 10-06-2012 03:59 PM

Yeah it over heated. Sometimes the current tracks can be damaged from this.

A few people will jump in here in a few and offer advise.

It's a short distance and can be repaired with a new wire run across the PCB invade there was damage.

R45VT 10-06-2012 04:14 PM

Can you post pictures of the top side again? It got hot in a few places away from the resistors.

psychokiller99 10-06-2012 04:23 PM

Quote:
Originally Posted by R45VT
Can you post pictures of the top side again? It got hot in a few places away from the resistors.


http://imgur.com/a/GiPGR#10

here you go. Sounds like a pretty extensive repair job and that sounds expensive.

EDIT: picture link

R45VT 10-06-2012 04:30 PM

It's not bad to do. Of coarse a new PCB might be best if it's cheap enough.

Looks like the resistors for the heaters go hot as well. Wow.

How are you at soldering? If you aren't experienced it's going to need to go to someone who can do it. You can lift the PCB traces off the board if you aren't careful.


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