# Transformers Have Any Value?



## ampaholic (Sep 19, 2006)

Trying to clean out some things and came across these transformers. One is a power transformer from a 1968 Drip-Edge Super Reverb I used to own. The transformer actually dates to 1967. I can't recall the actual troubleshooting but the note I put on it says the filament winding is open.
The second item is an output transformer from a mid-60's (I think) Traynor Bass Master with an open primary.
What I'm wondering is if these have any value? I'm not really thinking monetary value but more-so wondering if someone would go to the bother of having them repaired. Then again, monetary value wouldn't be a bad thing!


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## terminalvertigo (Jun 12, 2010)

If I had a vintage amp that had a replaced transformer, I wouldn't mind have a "original" faulty item to include in the future.


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## Paul Running (Apr 12, 2020)

ampaholic said:


> it says the filament winding is open.


If the other windings are serviceable, use as is and install a separate filament TFM.


ampaholic said:


> Bass Master with an open primary.


Is it open plate to plate or plate to CT? If your lucky it may be open at the termination...worth taking apart to have a look see.


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## jb welder (Sep 14, 2010)

Aside from mentioned above, I think even as scrap they are worth something for the copper & steel.


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## ampaholic (Sep 19, 2006)

I don't really have a use for them so am unlikely to do much troubleshooting. I just thought maybe someone with a SR or Bassmaster with a replaced transformer might go through the bother of repairing to bring their amp back to a degree of originality.
I hate to scrap stuff like this but sounds like that's the likely outcome!


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## Lincoln (Jun 2, 2008)

Have people started taking the old "cans" off their vintage but dead transformers, and putting them onto a new core? Numbers are on the cans, (end housings) right?


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## tomee2 (Feb 27, 2017)

I have a 68ish YBA1 with a replacement transformer on it. I might be interested in the dead output.


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## Frenchy (Mar 23, 2011)

Great paper weights !


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## Paul Running (Apr 12, 2020)

Frenchy said:


> Great paper weights !


I've used them for door stops on a windy day.


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## jb welder (Sep 14, 2010)

You can get them rewound for less than a new one if you can find the right shop. Maybe that is what @tomee2 is thinking?


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## nonreverb (Sep 19, 2006)

jb welder said:


> You can get them rewound for less than a new one if you can find the right shop. Maybe that is what @tomee2 is thinking?


Not sure of what shop in Canada would take that on. I know MM does it but it's costly.


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## ampaholic (Sep 19, 2006)

tomee2 said:


> I have a 68ish YBA1 with a replacement transformer on it. I might be interested in the dead output.


It's yours for the cost of shipping if you'd like it.


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## Patrice Brousseau (Aug 12, 2020)

I would guess that maybe Hammond could rewind the YBA-1 tranny?


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## tomee2 (Feb 27, 2017)

jb welder said:


> You can get them rewound for less than a new one if you can find the right shop. Maybe that is what @tomee2 is thinking?


I'm not sure what I'm thinking..haha! But yes, maybe rewound...maybe.


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## Paul Running (Apr 12, 2020)

Similar to why do people have pickups re-wound?


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## ampaholic (Sep 19, 2006)

Bass Master tranny on its way to (possibly) being reborn!


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## tomee2 (Feb 27, 2017)

So here's why I picked up that transformer (thank you ampaholic!) ..... to take this picture.










In the middle is the original YBA1 output transformer, on the left is the closest in physical size currently available from Hammond, the 1650N, and on the right is the "correct" replacement from Hammond, and new 1750TY.

The 1650N is a 4300ohm primary, but also has extended frequency response compared to the 1750TY. The lamination thickness is identical and the holes look to line up. If I swapped the bell ends it could look original. It has options to wire up as 4,8, or 16 ohm output.

The 1750TY currently costs less new then a 1650N. It has the 'correct' 3800ohm primary and only 1 secondary, for 8 ohms.

Which would you use to replace your blown YBA1 output? The correct 3800ohms, but phyically different, or a physically looking the same but 4200ohms primary with options for 4, 8,or 16 ohm output?

What changes, if any, are needed for the 4200ohm primary? 

The YBA I have was repaired several years ago with a 1650N, but it must have had another transformer at some point because there are extra holes in the chassis.


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## Paul Running (Apr 12, 2020)

tomee2 said:


> YBA1 output


What are you using for output tubes? Myself, I would try all three and then make a decision after bench testing and ear testing. In the end I would still keep all of them for future projects.


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## tomee2 (Feb 27, 2017)

Paul Running said:


> What are you using for output tubes? Myself, I would try all three and then make a decision after bench testing and ear testing. In the end I would still keep all of them for future projects.


Same as stock, which is EL34s.


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## Paul Running (Apr 12, 2020)

You shouldn't need to change anything with 4K2Ω plate to plate primary impedance:


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## tomee2 (Feb 27, 2017)

Paul Running said:


> You shouldn't need to change anything with 4K2Ω plate to plate primary impedance:
> View attachment 391206


Thanks!


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## jb welder (Sep 14, 2010)

tomee2 said:


> So here's why I picked up that transformer (thank you ampaholic!) ..... to take this picture.
> 
> View attachment 391112
> 
> ...


The OT size difference is one part of the big power increase of the YBA-1A over the YBA-1.
The 1750TY (50W) is the replacement for the A1312 (YBA-1), and the 1750RA (100W) is the replacement for the A1303 (YBA-1A Bassmaster MkII).
The 1650N is a generic ultra-linear OT.
The 1750RA has the larger size and 3800 ohm primary.
Not sure which version of YBA you are dealing with.

Like @Paul Running showed, a 10% difference in primary impedance would not be critical.


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## tomee2 (Feb 27, 2017)

jb welder said:


> The OT size difference is one part of the big power increase of the YBA-1A over the YBA-1.
> The 1750TY (50W) is the replacement for the A1312 (YBA-1), and the 1750RA (100W) is the replacement for the A1303 (YBA-1A Bassmaster MkII).
> The 1650N is a generic ultra-linear OT.
> The 1750RA has the larger size and 3800 ohm primary.
> ...


I've got a 68 YBA1, but the original output is very large. I did not know the YBA1A also used 3800ohms. So maybe the early YBA1s should use the 1750RA output?


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## jb welder (Sep 14, 2010)

tomee2 said:


> I've got a 68 YBA1, but the original output is very large. I did not know the YBA1A also used 3800ohms. So maybe the early YBA1s should use the 1750RA output?


'68 is not really what I would call early for YBA1. The early ones had 7027 power tubes and I guess that version is what used the smaller OT. Very early also had rectifier tube.
From schematic dates, it looks like there was overlap when both the 1 and 1A were being built.
So from that, and what you have found, it's possible that the bigger OT came with the change to 6CA7/EL34, rather than the MkII/1A designation.

The 1A is where they published the 90W power output spec.
It could be that they were already using the bigger OT with 6CA7's so they decided to take full advantage and beef up the power supply. I haven't looked into differences in the PT size. I'd guess the YBA1 would be using 50W PT where the 1A would be 100W.


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## tomee2 (Feb 27, 2017)

jb welder said:


> '68 is not really what I would call early for YBA1. The early ones had 7027 power tubes and I guess that version is what used the smaller OT. Very early also had rectifier tube.
> From schematic dates, it looks like there was overlap when both the 1 and 1A were being built.
> So from that, and what you have found, it's possible that the bigger OT came with the change to 6CA7/EL34, rather than the MkII/1A designation.
> 
> ...


I'm confused now. All the small rounded box YBA1s I've seen pictures of have huge output transformers, up until the bumper trim ones that seem to have smaller transformers. 
I say early because it's still the small rounded box, not the later bumper box. I agree 68 is not really early though. 66 would be, or 65?

Looking over (blurry) schematics the 1 and 1A used the same 68348 output part number in 1966. But I think the current Hammond 1750TY "replacement" for the 68348 that is given for the YBA1, not the 1A, is the correct impedance but wrong size.

I'm now thinking later bumper YBA1 and YBA4, could use the 1750TY
But the "Early" YBA1 and all YBA1A could use the 1750RA?

Maybe I should start a new thread about Traynor transformers? And get people with these amps to make good scans of the schematics from the original paper ones.


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## jb welder (Sep 14, 2010)

Maybe @Frenchy99 has some insight as to which of the YBA1's have the smaller size OT? He's gotta have a couple dozen of each flavour I would think.


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## Frenchy (Mar 23, 2011)

jb welder said:


> Maybe @Frenchy99 has some insight as to which of the YBA1's have the smaller size OT? He's gotta have a couple dozen of each flavour I would think.


I`ll give it a go ... lol

I`m not certain on the size of the very first model, the Dyna Bass head transformers since I dont have any. Pete documented it was only 40 watts and upgraded the model when it changed names to the Bass Master (YBA-1) late 1964.

The first Bass Master models had huge transformers, these are the 7027A models, these are almost un-killable. Biasing changed on the amps when switched to EL34 in 1968 and these also only came with Diode rectification. 

I noticed the first decrease in size transformer wise when the choke was dropped on the models (mid 1970) Still very huge transformers compared to the competition but they did shrink in size. The Bass Master stayed the same till 1974-5 , transformers reduced and then a new version came out (round bumper) with even smaller transformers, the amp went down to about 40 watts at this point again. This was the last and final Bass Master model.

Other Traynor model suffered a more decreased size difference ( Reverb Master, YBA-2, YGA-3/2 ) The larger bass heads always had the largest transformers. The YBA-1 rated at 50 Watts has larger transformers compared to the competitions 100 Watts models.... Pete Traynor wanted to give the best amp imaginable to the working musicien. 

So, to make a long story short, the 1964- Mid1970 models have the larger transformers. 

Dec 1964









Jan 1966









Jan 1967


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## jb welder (Sep 14, 2010)

Frenchy said:


> So, to make a long story short, the 1964- Mid1970 models have the larger transformers.


Thanks for chiming in Frenchy. 
Just to clarify, are you only speaking of the 1 and not the 1A (MkII) ?
And all 1A had the larger transformers?


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## Frenchy (Mar 23, 2011)

jb welder said:


> Just to clarify, are you only speaking of the 1 and not the 1A (MkII) ?


I was only addressing the YBA-1 



jb welder said:


> And all 1A had the larger transformers?


Hell yeah ! Every YBA-1A had huge transformers since they came out in 1968. Lots larger compared to the reg YBA-1


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