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September 24, 2020, 04:01:22 AM

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Author Topic: Trying To Repair a Traynor TBM 25...  (Read 3182 times)

debrad

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Re: Trying To Repair a Traynor TBM 25...
« Reply #15 on: August 27, 2020, 12:18:50 AM »
Thanks Enzo.

Sounds like my best bet is still pulling the 2SC2233s...to either test or simply replace.  I do have access to an oscilloscope so I'm curious to know if anyone thinks I should check anything with that BEFORE desoldering the transistors?

debrad

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Re: Trying To Repair a Traynor TBM 25...
« Reply #16 on: August 31, 2020, 10:02:20 PM »
Well...I was waiting to see if I could source some replacement 2SC2233 transistors before going any further but I still have some digging to do there so I figured I would try a pair of TIP41C that Enzo recommended in the meantime.

I'm happy to report that the amp now plays much cleaner and much louder through the speaker...even after several minutes!

There were a few buzzes and rattles so I can't confirm that everything is "perfect" yet but I'm 99.9% sure that's because the chassis is still separate from the cab and everything (including a bunch of the hardware) was sitting on a pretty shaky table top!

I guess my big questions now are:
  • should I be looking for other parts of the circuit that may have caused the transistor(s) to fail or can that just happen on their own?
  • are the spec. differences between the TIP41C and 2SC2233 transistors cause for any concern in the functionality (and stability) of this circuit?
  • will the spec. differences between the two transistors have any SIGNIFICANT impact on the SOUND of the amp (to be honest, I've never heard this amp as it's SUPPOSED to sound so I can't say if the current tone is better/worse/the same as it originally was)?
In other words, can I assume the problem was JUST a faulty output transistor (or two) and consider it "fixed" with the TIP41C swap or should I dig deeper for problems while also continuing to ultimately source the original 2SC2233 replacements?

 

Enzo

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Re: Trying To Repair a Traynor TBM 25...
« Reply #17 on: August 31, 2020, 10:41:01 PM »
Quire often, it is just outputs.  I usually replace the drivers too, but if it is working, they may be fine.  And if the two 1/2 ohm resistors are OK, and the 150, 150, and 22 ohm resistors are OK, likely it is fine.

SOlid state amps like this and a million others are massively fed back and self-correcting, so pretty much any transistors that will safely work there will sound about the same.

There is no bias adjustment, so if it works, doesn't get real hot, and sounds OK, then I'd stop fixing it.

debrad

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Re: Trying To Repair a Traynor TBM 25...
« Reply #18 on: September 01, 2020, 10:56:24 AM »
Thanks Enzo.  I really appreciate all the help that you and the others have given me on this.  I am going to spend a little more time really testing the amp today and then I'll find out if the owner has his heart set on 2SC2233 replacements or is happy to stick with this pair of TIP41C transistors instead.

Once all is good, I guess I can turn my attention to another Traynor with issues...a BLOC100K that I *THINK/HOPE* just needs the pots cleaned...

Enzo

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Re: Trying To Repair a Traynor TBM 25...
« Reply #19 on: September 01, 2020, 06:54:18 PM »
A guy brings me a 1969 Corvette with a flat tire.  I put a brand new Goodyear (or Michelin or whatever) on it, balance up fine, car drives fine.  Now do I check to make sure the guy doesn't have his heart set on an actual 51 year old tire for it?

debrad

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Re: Trying To Repair a Traynor TBM 25...
« Reply #20 on: September 01, 2020, 08:33:40 PM »
 :lmao:   :dbtu:

BTW...I happened to touch base with a fellow at Yorkville Sound (the company that makes Traynor amps) and he told me their current replacement for the 2SC2233 is a MJE15032.

So...even the amp maker themselves don't replace the output transistors with original parts!

Enzo

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Re: Trying To Repair a Traynor TBM 25...
« Reply #21 on: September 02, 2020, 01:51:39 AM »
The MJE150xx series are useful in a number of situations.  I use them

I suspect Traynor uses them in some other product, and has them on hand.  The MJE15032 is rated at 250v versus the 60v rating of the 2SC2233,  and 8A versus 4A, so it is overkill.  I am sure it works fine though.

In tube amps, a EL34 will sound different from a 6L6, but transistors don't work the same way, and especially in power amps, you can use pretty much anything that has the minimum specs covered.