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PROBLEM NOW SOLVED. THIS THREAD IS STAYING UP TO HELP OTHERS. In the end, Stephen saved the day and got me my replacement Output transformer fast and for only the cost of shipping it to me. Swapped the tranny and everything was back to perfect. Thanks Trinity!

I've been playing and loving my self built Deluxe since June of last year. You can see the thread from when I finished it here : viewtopic.php?t=1251

At band practice the other week, after about 2 hours of the amp being on, it went very quiet. It still sounds right and has the correct range of tone and distortion on the knobs (CORRECTION : distortion comes on a little earlier than before), it's just very quiet. You could whisper and be heard over it now. The sound is very similar to the problem I had in my initial build, when I missed an under the board jumper in the preamp. I'm wondering if it is an issue in the preamp again.

I've been trying to troubleshoot it for almost two weeks and I'm out of ideas, so I'm coming to you guys for help. Here is what I've done :

- swapped out all the tubes with a known good set = no difference

- used a different speaker = no difference

- continuity tested every individual part and connection I could while marking off the wires on the layout = complete continuity throughout. In fact, I can take one probe from any input jack and put the other on either speaker out and I get continuity

- check voltages = all tubes roughly within the range they were before, but V1 seems to have swung out the most.

My voltages
1st number = Trinity recommendation
2nd number = what I got when the amp was working perfect all these months
3rd number = what I'm getting now

12ay7 (v1)
Pin 1 - (120) - 120.1 - 100.7
Pin 3 - (2.0) - 1.9 - 1.9
Pin 6 - (123) - 118.4 - 136.8
Pin 8 - (2.0) - 1.9 - 1.9

12ax7 (v2)
Pin 1 - (167) - 151.5 - 151.9
Pin 3 - (1.1) - 1.2 - 1.2
Pin 6 - (175) - 187.4 - 185.9
Pin 8 - (70.5) - 43.7 - 44.6

6v6 (v3)
Pin 3 - (380) - 349 - 356
Pin 4 - (338) - 328 - 326
Pin 8 - (22) - 20.8 - 20

6v6 (v3)
Pin 3 - (382) - 350 - 354
Pin 4 - (339) - 329 - 326
Pin 8 - (22) - 20.8 - 19

Any tips or advice is appreciated.

Thanks,
James aka LowWatt

I'm going to reprint the schematic and again go top to bottom with continuity tests this weekend, but other advice or even areas of the circuit to look closest at would help.

Any ideas or recommendations of non-leathal things to try would be appreciated.

Getting desperate. Any advice? Anyone? I've continuity tested every connection 5 times over. I've touched up my soldering. I've swapped every part that can be swapped. Checked my voltages . Nothing makes any difference whatsoever. Checked every cap and resistor.

The 12ax7 gets warm and every connection seems to check out but there is zero orange glow to it, even after swapping it out. The 12AY7 isn't showing much either, but there is a slight bit of orange in there when it is on. Anything else I can be looking at in the tubes when I'm testing it?

I'm too broke to put this in a shop. To tell you the truth, this amp is one more frustrating week from a desperate craiglist ad so that I can replace it with something that works.

This amp worked perfect since June. What could it be? Where can I look? Any good online tutorials on troubleshooting an amp? Anyone want to just buy it outright from me?

Was the speaker you tried known good?

Have you checked all of the grounds?

Sounds like you've tried everything with the amp.

Did you check continuity on the jumpers you missed the first time? Remember, if there is an alternate path between components, that may be ringing out continuity and still have a break in the parallel leg.

Also, check the caps, any look "different", i.e. bubbled or leaking? Check around pin 8 of V2, that is the only voltage significantly "off" and around V1. If a cap is bad around V1 that would cause a difference, a bad cathode bypass cap would reduce gain and volume I believe.

Hope someone that knows more will chime in.
Hope this helps!!

I appreciate any and all suggestions. Thanks for the tips.

"Was the speaker you tried known good?"

Yep. Tested it with another amp and tested the deluxe with another cab. Problem is definitely the amp not the speaker or speaker cable.

"Did you check continuity on the jumpers you missed the first time? Remember, if there is an alternate path between components, that may be ringing out continuity and still have a break in the parallel leg."

All jumpers show continuity. The alternate path/parallel leg sould be a concern. I'm trying to check continuity both in one part and multi-part runs just to find anything.

"Also, check the caps, any look "different", i.e. bubbled or leaking?"

Caps look pristine.

"Check around pin 8 of V2, that is the only voltage significantly "off" and around V1. If a cap is bad around V1 that would cause a difference, a bad cathode bypass cap would reduce gain and volume I believe."

That's what I'll try next. Thanks for the advice.

James

Check the heater voltages on the pre-amp & output tubes. 6.3 VAC approx?

Input jacks clean & working?

Sounds like B+ is good.

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

Jacks are all clean and seem to be working fine. The tone is 100% the same no matter which jack I use on the input or output.

The preamp tubes seem to glowing fine now that I switch the tubes to some current EHs. I think the design of the Amperex I had in there just made it hard to see anything on the tube. Tone is still the same. Quiet, a little muffled and distorted.

Heater voltages are measuring 2.8V on every connection. Could that be the issue? I'm assuming I should be seeing 6.3V. What does that mean?

NOTE : Just realized I should be measuring it with a probe on black and the other on red. This is reading 5.8V.

5.8V AC across the heaters, is a little low. Not sure what the effect wouldbe. Pull out the tubes & see if this rises to 6.3 or greater. It should be able to hold 6.3VAC

What is your Mains voltage when you measure this?

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

It measures 6.2VAC without the tubes. How do I safely measure the mains?

Measure them in the wall socket with your probes.

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

Thought I looked up the right way to do this online, but I guess not. One of my probes is now destroyed and an outlet is gone. I won't have the chance to hit CDN Tire and replace the DMM probe until later in the week, so it looks like this one is on hold.

Please feel free to give more suggestions in the mean time and I'll try them all when the part has been replaced.

Can someone point me to the correct way to measure the mains voltage with a DMM online. Something that really dumbs it down to the proper DMM setting and which colour goes in which hole would be most appreciated.

Ouch,

Maybe you set the DMM to DC?

Set DMM to AC Volts. Set it to greater than 120 Volts AC range.

Put One probe in one slot, the other in the other slot. Should measure around 120 Volts AC. In TO mains should be OK.

Must be something else.

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

Got the replacement leads. Wall voltage is good. What should I try next?

do you have alternate power tubes? The voltages should work OK. Certainly not as quiet as you say.

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

The voltages on Pins 1 and 6 look real suspicious to me. I would check for poor solder joints in the circuitry around V1, and possibly reflow some of the joints. At the more unlikely end of the scale it might even a faulty socket. If V1 is having problems then naturally it will affect both channels. Also check what the preamp rail voltage is going to V1.

_________________
Great tones come in small glass jars!

I've tried this all out with three different complete and working sets of tubes (different pre, power and rec every time). This change was definitely a sudden one. After two hours of great play and awesome tone at practice that week, the amp just got suddenly very quiet. All swapable parts (tubes, speakers, cables, guitars, outlets) were swapped.

Ya, that's where I had the biggest difference from my original measurements, so it has the majority of my attention. Also the sound change is very similar to a problem in the pre before so I'm leaning towards that being the issue (still I know little about amps and electronics, so I'm willing to try anything).

I've reflowed the solder, but I'll look closer in the morning with fresh eyes to see if anything is out of place or if even two parts are touching that shouldn't be. Failing that, I'm thinking my next step is to unhook the circuit board, check the back as well too, go over it carefully, I might as well resolder the preamp tube sockets with the board out, and connect it all back together.

It's the slowest most tedious way, but at least then I can rule out dodgy soldering in the preamp. Everything looks good from the surface, but I'm thinking there is always the chance that something is amiss undrneath the board. All the continuity tests check out, but as was mentioned before, there could be an issue with a jumper that a continuity test is missing because the signal can get from point a to b via an alternate route.

Oh well, fresh eyes tomorrow. Keep the suggestions coming, I'll try them all and report back.

What happens if you wiggle V1. Just thinking about the socket. See if there is a position where it gets loud again.

You should be able to test without removing the board. Last resort.

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

Before doing anything really radical like removing the board, it would be a real good idea to also measure the preamp rail voltage feeding V1. I doubt that it's changed much, since we have decreased voltage on Pin 1 and increased voltage on Pin 7. But it will help build up a picture of what's going on. Also are the grids (pins 2 and 6) solidly at 0V?

_________________
Great tones come in small glass jars!

No amount of wiggling changes the tone in any way.



0 V with no movement on pins 2 and 6. Where do I measure the "preamp rail voltage feeding V1"?