Epiphone Pacemaker 50T PT short

[maxkracht]

Maybe a blues jr replacement transformer? Mounting holes will be the hard part.

[Stevem]

The BJ does not use a tube recto and runs the output plates up at 329 which is way about where his B + is.

[maxkracht]

You are right, I didn't remember the BJ had no ht center tap, was just thinking something closer to 250v would be more like it. I'm sure 300v hammond is just fine but maybe a bit higher than the original?

[maxkracht]

https://www.hammfg.com/electronics/tran ... lassic/200

269ax?

[Stevem]

Yes, that’s even better for his needed level of V+.

A 6X4 has a 1.3 to 1 voltage ratio.

[angelodp]

I do not see a CT on the heater winding, on the schematic or within the amp. Rather the heaters are grounded by way of the light bulb frame.

A

[maxkracht]

You should be able to unground the lamp connection and install a humdinger pot or a couple resistors for an artificial center tap. 100ohm 1/2w resistors can sorta act as a fuse if things go horribly wrong. I would probably connect 100ohm resistors to the output tubes cathodes. Can also leave it like it is.

[angelodp]

Hey guys, yeah so looking at Hammond, I need to source a horizontal mount not vertical. Appreciate eyes and analysis on this. I'll get back when I get the PT and see how it goes.

P-TGP-001. over at AE?

Best A

[Stevem]

Yes that will work electronic wise, ( don’t know about physical wise ) but you will need to add another dropping resistor before the first filter node to bring down the 360 volts that you will have off of the 275-275 windings down to the stock schematic reading of 235.

I would say that if you get the V+ down to even 250 that will be pretty good, but you will then have to increase the resistance of the output tubes cathode bias resistor which is now 270 ohms.

Looks like a added 1 ohms per volt, or a total of 285 ohms should do it to get the outputs to idle back where they should.

Looks like the original PT was a 185-185 volt deal.

I do not have time right now to figure out the ball park resistance you will need for the new added V+ dropping resistor, but it looks like the amp is idling at about 95 ma.

To keep things nice and cool I would go with a 10 watt resistor for this.

[maxkracht]

Double check that the mounting hole spacing is correct. It is easy to get one that is close but doesn't quite work and end up needing to drill some new holes or make a bigger cutout. You can mount the hammond sideways by chopping off an ear or taking off one side of the bell. No idea if that one is the correct size either. Need to measure and check data sheets.

[angelodp]

https://www.hammfg.com/files/parts/pdf/290HAEX.pdf

This has 275/0/275 136ma. and the mounting holes are spot on. has the 6.3vac

The Primary is a bit strange but I can see a good option with 120vac

Ya think this will fly?

[martin manning]

That one shows 100 mA for the HV secondary. However, if it worked for a 5F10 Harvard with 2x 6V6GT, then it will work for your 2x 6AQ5. There is a 120VAC primary version 290HAX https://www.hammfg.com/files/parts/pdf/290HAX.pdf you could use if you don't need to operate internationally.

[angelodp]

Thanks Martin, Max and Steve, waiting for owner to give me go ahead. No need for Int. so 290 HAX seems best. Will still need a dropping R and look at bias.

A

[martin manning]

Also note the rectifier is a 6X4, with 6.3VAC indirect heater that should have its own winding. The above PT has 5V rectifier winding.

[Stevem]

Here’s the power supply of one of my Univox B45 amps that use the 6X4 recto and it’s filaments are run off the same 6.3 volt winding as all the other 3 tubes in the amp.