trinityamps.com

Hello folks,
I'm starting to troubleshoot a minor issue I'm having with some static-ish noise on both channels of my TC-15. I thought I'd post here for some pointers on where to start looking, or to see if this is a symptom for a specific problem someone else has had.

It's a fairly light static that shows up at medium to higher volume - at bedroom levels it's absent. The static is only there when the guitar is being played and is really evident when notes are trailing off. It doesn't seem to be vibration related - I've heard the same noise using the TC-15 to drive another cab/speaker.

I've also swapped out power and preamp tubes to eliminate that possibility (except for the rectifier).

I noticed it when I was doing some recording. Here's a clip of the noise from the EF86 channel. It actually still sounds pretty sweet when I didn't "dig in" in this clip.

http://soundclick.com/share?songid=6890696

Thanks in advance,
Rich

Can you try wiggling the tubes to see if the contacts in the sockets are suspect?

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Thanks, I'll try it when I get it put back together. I've got it opened up checking for bad solder joints and any other issues. I did also check the filter caps confirming that the resistance is greater than 15 kOhms - I believe this was suggested in the manual. Some of my wiring on the tube sockets (I'm looking mainly at the power tubes) are dangerously close to one another and I've tried to space them a little better. I might just put some insulation on those joints as well. Can't hurt.

Re-check / solder your grounds. I have seen this happen with poor solder joints at the grounds.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Interesting issue - It's still cracklin'. No problems with the grounds - they're all registering around .5 ohms. Can't find any other obvious mechanical or connection problems. I did measure voltages to see if that would point to any issues. (JJ Tubes)

-----------------Pin 1------Pin 3------Pin 6------Pin 7------Pin 8
V1-(12AX7)----142-------1.3--------142--------------------1.2
V2 -(12AX7)----161-------1.2--------264------------------161.8
V3 -(12Ax7)----246--------x----------252------------------61.4

V4-(EL84)-----------------7.4---------------------357
V5-(EL84)-----------------7.4---------------------355

V6-(5AR4)------------------------------------------------------360
V7-(EF86)-------67-------1.6----------128--------------------1.6

I did check some spots on the board, and everything seemed to correspond well with the reference figures on the layout. The only possible issue I saw was for voltage on the turret where the V4-V5 cathode bypass cap and resistor connect (R21/C12). I measured 7.4 volts there. Is that low?

No voltage on the board material or the pots housings.

Divide & conquer. Remove v1 and see if you get a craccke with it just sitting there, if not, remove v2, then v3. See if you can isolate a section of the amp.

Dont trust even new tubes BTW.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Ok. I think I've got it fixed. I disconnected the crunch/munch switch and wired direct to the tubes with the 5k primaries. This seemed to correct the static problem, so either my switch is dicey (it is a flimsy one), or I had a cold solder joint on a v4 or v5 tube socket or on the switch somewhere.

While I've got it open, I'm going to replace the switch with a heavier duty one, clean up some sloppy lead dress, and probably install a choke - just to give it a try. Though i can't imagine it sounding much better than it does now.

I'd put a better switch back in and seee if that's the problem.

Good news!

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps