Flextone 1 HD Problems, just makes a loud buzz?
on 2010-05-12 22:02:48
OK, I'm guessing the response for this question is going to be "take it to an authorized repair center" but since the closest one is over 2 and a half hours away, hopefully I can get a little more here.
I've got a Flextone 1 Head that I've had for going on 9 years. The thing has always been a tank, I've never had any serious problems with it, up until very recently.
It started with the Ch. Volume control going batty. When turned from 0-5 it worked great, above that, it went schitzo, never knew what it was going to be. That was fine, because I just carefully set it to max, saved it, and left it parked at 0. This worked for a while, but then the amp started jumping into edit mode and changing the volume to 0. This amazingly only ever happened during practice, and a quick power reset usually cured it.
Well, at a show last week, it wouldn't stop jumping into edit mode and turning me down to 0 volume, and for the first time a very loud buzz was coming out of my cab. I borrowed another amp for the show, and started digging in to mine this week.
The volume and jumping to edit mode was simply a case of a dirty pot, a little contact cleaner and a good workout cleared that right up.
The buzz, on the other hand, has simply gotten worse to the point of the amp being unusable.
As a two way radio technician, I know my way around most electronics, so here's what I've got so far: I'm guessing that the transformer is going (has gone) bad. The buzz is on all the speaker outs. And with or without speakers hooked up, the XLR direct out and the FX Loop out, which leads me to believe that it's not a failing/failed final (my first suspect) as I'm guessing the audio for both those jacks gets split off well before then. It doesn't matter if there is an instrument hooked up or not.
The only thing I have done so far that has affected the buzz at all, is to disconnect the front end board (audio/TubeTone board? The one with all the controls on it) . When I power up the amp with that board disconnected, the amp stays clean for about 30 seconds and then starts buzzing away again.
Seems to me that when the transformer gets a good load on it, it starts buzzing away. I don't know what the voltages are supposed to be coming out of the transformer, but I did see some of them dropping as the buzzing kicked in. Can't remember what the drop was or which lead, but I can double check if needed.
I should note that the buzz is quite loud when it's hooked up to a cab, even with Master volume at 0, and turning volume up does indeed make the buzz get louder. I've taken a very close look at every solder joint and connection, and retouched anything that looked even slightly sketchy, but to no avail.
So, I guess I'm just wondering if anyone thinks I'm on the right track with the transformer? Anyone else had this problem? Are replacement transformers still available? Anything else I should be looking at? Specific voltages to check, etc?
Any help would be greatly appreciated.
The information above may not be current, and you should direct questions to the current forum or review the manual.