Author Topic: Power transistor cross-reference  (Read 3087 times)

Offline duskb

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Power transistor cross-reference
« on: October 03, 2011, 12:46:40 PM »
I'm hoping for a bit of clarity from the more technically experienced. I have a '73 Rhodes and the Delco 120725 power transistor pair has blown. No news there. However, recently I came across a sheet that shows the cross reference for the this as the DTG-110B (which I also can't find). This sheet also shows several other germanium transistors, some of which I have found are still available. Who would I talk to to determine the validity of this cross reference sheet? Would any of these replacement transistors be appropriate for use (as this sheet claims) for direct plug and play with the fender amplifier or is extensive modification needed to make them work?

Perhaps some tech savvy guys out there might be able to help me make some sense of this sheet?


Offline maestro

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Re: Power transistor cross-reference
« Reply #1 on: October 03, 2011, 01:53:03 PM »
I spoke with a electronics supply store today - DTG-110B is available (though only 1 of their major distributors carries it) and it is about $130 per matched pair and the rhodes uses two pairs...so this is a steep repair. The store said there were no cross-listed parts for this model number. Bummer.

Offline duskb

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Re: Power transistor cross-reference
« Reply #2 on: October 03, 2011, 04:57:13 PM »
Well that's the thing. This particular sheet shows this part as a legitimate cross-reference and I found a few pairs of this part on eay for $50 for 3 of them. If this part is a legitimate cross-reference either no one has caught onto it yet, or the sheet is in err (I'm pretty sure I'm not reading it wrong). It's worth trying to research.

This sheet came straight out of my Hammond tech's repair book full of old documents (when I explained the problem he pulled out this sheet). He seemed to think that was an easy and inexpensive repair after looking the sheet over. I also don't want to go out and spend $50 on the wrong amps and another $200 for repairs after blowing up the rest of the working cardl, hence why I was looking for a second (knowledgeable) opinion.

If you don't mind, what store did you call and would they know anything about interpreting cross-reference sheets?

Offline maestro

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Re: Power transistor cross-reference
« Reply #3 on: October 04, 2011, 11:48:31 AM »
If you are cross-referencing DTG-110B as the replacement, then yes, I can confirm that it is the correct replacement part (and only one that I know of). Unfortunately it is important to use matched pairs to prevent problems down the road, and getting them as a set is expensive. Your ebay find probably won't have these matched up, yes?

Offline duskb

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Re: Power transistor cross-reference
« Reply #4 on: October 04, 2011, 03:10:56 PM »
If you are cross-referencing DTG-110B as the replacement, then yes, I can confirm that it is the correct replacement part (and only one that I know of). Unfortunately it is important to use matched pairs to prevent problems down the road, and getting them as a set is expensive. Your ebay find probably won't have these matched up, yes?

I don't think these are matched but at $50 for three I would imagine they are plentiful enough to make it work. The sheet does clearly show that both Gulbransen and ECG made a PNP Germanium transistor that was a direct swap for the DTG110B. One reason I'm suspicious of the ECG part is that the sheet also shows that the same part number is a direct replacement for the DTG600. I have no idea what that is but I doubt it's the same part or guys would be using it.

Offline maestro

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Re: Power transistor cross-reference
« Reply #5 on: October 05, 2011, 12:09:31 PM »
Is the 110B germanium?

Offline AvionKeys

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Re: Power transistor cross-reference
« Reply #6 on: February 13, 2019, 01:24:48 PM »
We've been looking into this recently so I thought I might add that another cross reference is the NTE121.
And yes these are Germanium.

I can't say that these power amps are truly worth the cost of repair as even these are somewhat expensive, but I understand some people wanting to match the other side or keep things very original. So I hope that helps.  ;D

Cheers,
Morgen