Seeburg L100 T751 Power Transformer Replacement

[pheff]

Hi all,

I'm redoing a Seeburg L100 that I got in original condition with a blown 5A PT fuse.  
I replaced all the caps that were out of spec.  However, the main PT T751 smokes and bubbles when powered on now.  I'm getting 20+ volts where I should be getting 6.3 volts from the PT before it starts smoking.
Assuming that someone tried to run this machine with bad caps and blew the transformer I need to find a replacement.  Originals are impossible to find so I'm looking at other options such as using a combination of PTs to get all the secondary voltages I need. 
I have the schematic with the secondary voltages but some of the values are hard to read.  Can someone confirm these are the right voltages:  25v, 155v, 6.3v, 30v, 325v, 6.1v, 6.1v, 6.5v and 5.8v?  I have attached the schematic for review.
If these are the correct values, what is the purpose of the 6.1, 6.3, 6.5 taps (are they not for filaments)?  Can I use 6.3v for all of them (assuming they are from different PTs so I don't draw too much current from a single PT)?  Also, I am having trouble finding a PT with 5.8v tap - plenty with 5.0v.  Could I use the 5.0v tap for the 5.8v (it would be slightly out of 10% tolerance)?
Any help would be appreciated.
Thanks,
Paul

PS:  I can't upload the schematic so here's a link to it: drive.google.com/file/d/1kICW-hnqEUb717Hv8IOBdgVEfcftGoAe/view?usp=sharing

BTW, rewinding appears to be out of the question.  Most of the people that used to do that work have closed up shop.

[jukenorman]

Hi Paul,
While not impossible, cobbling together transformers to produce the required outputs is fraught with issues - it's not just the voltages but you would also have to calculate (estimate?) the current draw for the windings. And if it was possible to reduce/combine the number of windings, wouldn't Seeburg have done that?

I think you need to double down on finding a replacement transformer! You are aware that the K/KD 200 will use the same unit? I have checked the 201 schematic and the T501 transformer in the selection receiver has exactly the same windings and even the same wiring colour codes so that is another option - 161/201/L101 jukeboxes. I haven't checked the V/VL jukeboxes. Incidentally, I've just looked and there's a 201 selection receiver (TSR6) on your US ebay - looks pretty rough but the transformer might be good! Apologies, I've just realised it's located in the UK!!!  But still, not impossible to find!

I also find it difficult to believe that you can't find a shop to do a transformer rewind for you.

Norman.

[pheff]

Hi Norman,

Greetings from near Aberdeen, Maryland Thanks for your message - you have answered my questions and provided some options. I was aware that the K/KD used the same transformer.

Actually, Heyboer Transformer here in the US, makes a replacement transformer. They just contacted me with the info and specs. Looks like they make all the 6.x volt secondaries 6.3V. Given the filament +/-10% range that covers the 6.1V and 6.5V taps.

I'll update this thread once I get the new transformer installed.

Thanks again,

Paul

[gordo]

G'day Paul,

I was chasing one of these transformers a while ago for my KD 200 (same problem that you mention).
I found that they were available from Jukebox Revival in The Netherlands.

I ended up finding a NOS with a local collector, however, never installed it as I located the problem.

Good luck, I was not looking forward to installing it, it sure looked difficult to me.

Regards

Gordon....

[1inxs]

Paul,
Most Seeburg Jukes have multiple windings in the transformer. If you have a transformer that all works except the 6.3 volt, you trace the wires and cut them and install a 6.3 volt in that leg. Just find a good location in the amplifier to mount the new transformer where it won’t affect anything and you’re good to go.
Good Luck!

[pheff]

I got the replacement PT from Heyboer and tested the secondaries prior to install and it was on target with the voltages. It dropped right in without a problem.

After redoing the boards (some were cracked - thank goodness they are single sided), I hooked a thermometer on the PT and slowly added individual connectors and tubes and monitored the heat (and thereby the draw on the PT) and found the problem on the TECU board with the 6X4, 0A2 and 2050 tubes on it. It's looking like the 6X4 rectifier is the cause of the problems.

Would a shorted 6X4 cause the excessive draw on the PT? I have one on order along with some strange caps from the TPAU (transistorized Pre-Amp) mounted on the Mech.

Any suggestions would be greatly appreciated

Paul

[jukenorman]

A shorted 6X4 would certainly not be doing the transformer any good, that's for sure! If that circuit board is in poor condition, Jukebox Revival in the Netherlands have repro boards.

Norman.

[1inxs]

Paul, I would verify the solder connections in relation to the 6X4 tube. A bad solder joint can cause a heating up issue. The 6X4 is not known for shorts. Check the solder connections and replace the 6X4 with a known good one and all should be well. I have seen Seeburg with the 6X4 and OA2 tubes installed in reverse and caused the issue you mention.