Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Solid State => Topic started by: TerryD on August 16, 2016, 02:58:31 pm

Title: Tiesco Checkmate 88 distortion that is unwanted and reverb tweek
Post by: TerryD on August 16, 2016, 02:58:31 pm
No doubt that this has very little power but I'm getting unwanted "mild and just a little" distortion at any volume from low to even lower.  Any advice on this old amp?

Also the reverb is very trebly...any fix for that?
Title: Re: Tiesco Checkmate 88 distortion that is unwanted and reverb tweek
Post by: PRR on August 16, 2016, 04:04:51 pm
As I have never seen a Tiesco Teisco, a link to a schematic would help.
Title: Re: Tiesco Checkmate 88 distortion that is unwanted and reverb tweek
Post by: pompeiisneaks on August 16, 2016, 04:29:11 pm
Here's the one I can find:

http://s27.photobucket.com/user/irishronin/media/teisco88-a.jpg.html (http://s27.photobucket.com/user/irishronin/media/teisco88-a.jpg.html)

not sure if that's the right one, but maybe?

~Phil
Title: Re: Tiesco Checkmate 88 distortion that is unwanted and reverb tweek
Post by: pompeiisneaks on August 16, 2016, 04:30:09 pm
Also, as old as that amp is, have you checked the electrolytic capacitors?  Tubes are a first choice, though, but being that it's that old, it may need new caps.

~Phil
Title: Re: Tiesco Checkmate 88 distortion that is unwanted and reverb tweek
Post by: TerryD on August 16, 2016, 05:22:46 pm
No, this is solid state.
Title: Re: Tiesco Checkmate 88 distortion that is unwanted and reverb tweek
Post by: pompeiisneaks on August 16, 2016, 06:37:14 pm
Hmm then that schematic is wrong of course, being that it's a Teisco 88 tube amp.  Any schematic?  Sometimes it seems teisco put them on the inside panel?  If not, its going to be hard to troubleshoot.  It could be power filtering, like I mentioned, but I don't know if that impacts SS like it does tubes.  Otherwise it may have a Fet/mosfet that's going bad but I'm not great with SS myself.  Pics of the chassis if you don't have a schematic may help as well?

~phil
Title: Re: Tiesco Checkmate 88 distortion that is unwanted and reverb tweek
Post by: PRR on August 17, 2016, 05:59:01 pm
Amp of that age, working blind, full re-cap may be a path to try. At least all the small electrolytics. There's one or two BIG e-caps for the main power supply. They are past peak freshness but if they haven't leaked (yet), and there's no BIG buzz, you might leave them while tracing crap-signal problems.