18Watt.com

hello all,

I just picked up a Trinity amps Tweed ( not a kit ) with power scaling ( VRM ). The bright channel is working good, but when I plug in the normal channel I get a farting/spitting sound on attack and eventually, the sound cuts off. I tried replacing tubes without any change. I quickly looked for a loose wire or component on that input but couldn't find anything. Could this be related to the power scaling module ? could a bad DC blocking cap do this ? Actually I could argue the bright channel is showing earlier breakup than I am used with this desing... As you can tell, not a tech speaking here, I am a player, not a builder ! Please help me figure this out.

The interaction between the volumes doesn't seem to be what I am used to with 5E3's but if there is an issue with the input of the normal channel, that would likely have an impact I believe. It as been impossible to get anyone at Trinity, I actually have been trying to get in touch for weeks but not getting answers to emails or phone messages. If anyone knows something, please advise !

Any ideas/suggestions will be highly appreciated.

P.S. I have been incapable to reach Trinity for several weeks. Does anyone know somthing ? Still in business ???

Claude

The way you describe it this sounds like a bad solder joint to me. Check the circuit of the preamp channel you are having trouble with. Could also be an overheated part when soldered too long. But check the solder joints first.
The tube can be good, but one of the pins might not be grabbed well by the socket's clamp.. or just slides next to it. Check for a crooked tube pin. Make sure the tube goes in and out smoothly.
Also, the input could be a suspect too. look for shorts, bad contact of the jack input, ground? To rule out the inputs: plug the guitar cable into the bright input (which works fine) and jumper from the joint of the 68k resistors of the bright channel directly to pin 2. First disconnect the wire that is soldered to pin 2.

My L'il Dawg Tweed Deluxe clone was doing this for a little while. I tracked it down to spotty contact between the offending input jack and ground. In my case it was the bright channel/low input. It was jumping between no sound, low input sound, and high input sound. It was mechanical and vibration sensitive. I loosened and re-secured the nuts on the inputs and it went away. Worth a try?