Hello,
I've recently acquired one of the transition model HD 130 musicman with the transistor preamp.
Unfortunetely the amp doesn't work properly even after doing a cap job. I knew there were issues with the amp when I purchased it which is why it was cheap. It didn't seem like it had the symptoms of a blown transformer.
The amp has a very light fizzy, farty sound when I strum the guitar fairly hard so there is really no tone atm. I replaced all the main caps and it still sounds the same as before.
Could this be a transformer issue? I know that the valves are fine and they are glowing nicely. I also notice the standby severly flickering in intervals. This is especially noticable when its on the high mode. Low mode has less flickering.
Has anyone else had an issue like this before?
Thanks
Levi Pleiksna
Fizzy
Have you checked all of the voltages in comparison to the schem? That should be item one. Check for high voltage readings on the finals and the plus and minus 16v on the preamp side. We'll start there.
Pilot Light
I'll deal with the light, and leave the real problem to Mike :)
Are you saying the on/off light is flickering? If so, I would not be alarmed about that. IIRC these are neon, and they simply die slowly over time (eg: flicker) rather than burn out like a regular bulb. On the early Musicman amps the manual even stated that the light may not work under certain conditions. One of my Musicmans has been flickering for 15 years... one of these days I will buy the .75 cent part to fix it - LOL!
Fizzy
After checking voltages, if they are all OK, and ASSUMING the tubes are good, I'd go with bad drivers in the driver board. Remember, this is just a SWAG! Mike.
Is the fizz in the background?
Hi there, is the fizz sound in the background of the sound? Sorta like hearing a distorted ghost note behind the real guitar note?
Sincerely,
Lars Verholt
Yes
Wanted to give you a direct reply because you have had the same problem by the sounds... There is no real note though just the ghost note :/
Bad crossover
It's a distinct possibility that you have some crossover distortion. This can happen either due to bias being set too cold or there is a defective part somewhere. A leaking coupling capacitor, for example, could introduce this problem. In your amp we're talking C35 and C36 both 20uF/25V.
Sincerely
Lars Verholt
Thanks
Thanks for your replys guys and sorry about the late reply. Mike I will check these first up. Which schematic are you referring to?
Lars that is exactly what it sounds like, I couldn't have described it better! Are you an author?
LP
fizzy
Listen to Lars!
T-shirt slogan?
"Fizz is for tonic water, not for amps"