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Website, Store => Support => Topic started by: yumchild on February 05, 2011, 03:19:02 AM



Title: I confess I did something really stupid...
Post by: yumchild on February 05, 2011, 03:19:02 AM
Turned the power on, turned the standby on, no sound...  Turned the volume up, no sound...  bypassed my effects and plugged direct in with the guitar volume all the way up, no sound... Can you guess whats next?

After about a minute I realized I did not have the speaker plugged in.  Powered off, plugged in the speaker.   Powered on again and ... after it warmed up, the sounds were, well not right.  Its, kind of choppy and unpredictable at loud volumes.  I have not been brave enough to turn it back on for quite a while.

This is my 36 Watt TMB / EF86 combo.   Nik built the chassis, I built the cab. 

I was too upset to deal with it for a while, but now I'm over it and ready to face the truth.  Probably needs a new OT, but how do I know for sure?  Would it be safe to buy new tubes and test normal playing, or would I just be throwing new tubes away?

Is there a simple test I can do to tell if the OT is blown, or maybe test a few caps or resistors?  I'm not really comfortable with poking around in the chassis while the amp is on.  Is it possible to do offline checks of some sort?  The amp has not been plugged in to power in more than a month so the caps should be drained.

I could take it to an amp tech, but I don't really know anyone locally and I'd like to see how much I can figure out myself.


Title: Re: I confess I did something really stupid...
Post by: cmoore on February 05, 2011, 04:34:29 AM
Where do you live.?
I assume it worked 100% fine before this little incident.? all kinds of things are possible if you start getting fly-back voltage. You need spare tubes anyway. put in some different power tubes and see what happens. If you are not comfortable working on amps/don't know how; I would not suggest pulling the chassis.
I have seen a few blown OT's, but not way near as many as people think. Don't give up too fast. Try some new power tubes and take it from there.....
Best


Title: Re: I confess I did something really stupid...
Post by: yumchild on February 05, 2011, 05:06:26 AM
Where do you live.?
I assume it worked 100% fine before this little incident.? all kinds of things are possible if you start getting fly-back voltage. You need spare tubes anyway. put in some different power tubes and see what happens. If you are not comfortable working on amps/don't know how; I would not suggest pulling the chassis.
I have seen a few blown OT's, but not way near as many as people think. Don't give up too fast. Try some new power tubes and take it from there.....
Best
Thanks Hired Hand,

Yes it was working beautifully till then.  I'm in the Spokane Washington area.  I've built some effects pedals and done simple amp repairs.  I have a multimeter and get how to solder.   Just not too excited about taking measurements while the amp is on.  I will try a new set of tubes and let you know how it goes.



Title: Re: I confess I did something really stupid...
Post by: grod915 on February 05, 2011, 12:25:46 PM
Is there a simple test I can do to tell if the OT is blown, or maybe test a few caps or resistors? 
     Yes! Yes there is:
http://www.premierguitar.com/Magazine/Issue/2007/Apr/The_Super_Secret_Transformer_Tester.aspx
    Article by the venerable RG Keen.


Title: Re: I confess I did something really stupid...
Post by: JefferyWalsh on February 05, 2011, 01:16:47 PM
Is there a simple test I can do to tell if the OT is blown, or maybe test a few caps or resistors? 
     Yes! Yes there is:
http://www.premierguitar.com/Magazine/Issue/2007/Apr/The_Super_Secret_Transformer_Tester.aspx
    Article by the venerable RG Keen.


This is very good article.And the trick that mention in it are really useful and cool.


Title: Re: I confess I did something really stupid...
Post by: yumchild on February 06, 2011, 09:36:22 PM
Oh man, very excited to get this link to test the OT for shorts!  thanks so much for that.  I will try it and let you know the results.


Title: Re: I confess I did something really stupid...
Post by: yumchild on February 21, 2011, 06:32:31 PM
Great news, I replaced all the tubes and this tone machine is back to fully functional!

Thanks everybody.


Title: Re: I confess I did something really stupid...
Post by: grod915 on February 21, 2011, 09:24:48 PM
Cool! 8) (I love a happy ending)