6973 tubes?

Oh goodie, more expensive things that are bad.

Two of the 6973 Output tubes have shorts, the other two check OK and are newer RCA's.

NOS 6973's seem to start at $50 each.

Electro Harmonix apparently sells a new Russian made version for a good price, it looks pretty puny to me, does anyone know if they can handle the 12 watts the originals do? and live longer than a week that is.

There are a couple Subs for them also but they only handle 10 watts, not that I really need more than that but it'd be nice to have all it's capable of.

Any recommendations as to the best way to go?

Eric,
EH 6973's are generally fine--however, they did have a "bad run" of them a year, or so ago--be sure the code number indicates at least late last year ! I have used many "sub's" in home use with-out any problems that I am aware of--so it's up to you to decide. Ron Rich

It looks like I'll be going with a sub or the EH tubes, a pair of NOS I was bidding on went for $77, I could get all four of the EH tubes for that.
I don't really need the full 24 watts for home use anyhow.

Yeh the 6973 tubes sure are getting pricey, aren't they?

I bought a couple of the EH 6973's, if they work out I'll get another pair later, they're only about $36 for two.

I've been busy recapping the amp with a kit I got from Bill Bickers, a Baggie stuffed to bursting with Caps! I didn't count them but there's a load of them, spent 6-7 hours yesterday working on it and I'm not done yet, I still have to do the Filters and the two boards for Channel 1, it's my first time using a Kit so it takes a little time to learn the schematic and location of all the parts, recapping an old TV will seem easy after this.

I reinstalled it after doing the first two boards for Channel 2, to make sure I wasn't screwing it up, I was happy to hear both channels working now, two still sounded a bit muddy but I was still using the shorted 6973's just in case something went pop, I also hadn't recapped the Output section and didn't want to overdrive the new tubes.

From the looks of it I think the channel might have been dead because the very first cap after the input was crumbling to bits!

Questions: Would it hurt/help to replace the small Selenium Rectifier with a Diode, also the one on the Mechanism? Would they need to have dropping resistors added or not important?

In other news I picked up a Remote Volume Motor and shaft for this amp, it had one at some time in the past, the screw holes show evidence of that, I don't have the Controller ("Baby Shoe") yet but it looks like one could be built from common parts?

I was looking at the Autospeed controllers on eBay, this apparently used a tube model with two 6V6 tubes, will a later Solid State model work in this box? It has the vent screen and screw holes in the bottom of the cabinet where it mounts.

Eric,
Which model amp and which model jukebox do you have ? Ron Rich

Hi Ron, the Amp is an SHFA1 Code A, the Box is a Q100 SH, I was wondering if this is the correct amp for this machine?
The Amp seems to have been built in late 1958 based on some of the date codes found on transistors and Filter caps.

Eric,
I usually do not replace either rectifiers, unless they test bad--other people like to do so--
A Transistorized Autospeed will be just fine in that unit.
The SHFA-1 is two years older then the phonograph, and never had a "motorized" volume control.
Ron Rich

Thanks for the info Ron, I see now that the Motorized volume control is someones modification, the chassis was cut to accommodate it and a control with the slip clutch was installed.
From the mounting holes that were added it's apparent they must have cut away a part of the Motor mounting bracket to clear the plug for the Remote Volume Control.
I thought something was amiss when I first saw it since the holes were cattywompus.

I'm guessing this model originally used a non motorized control, a remote potentiometer that plugged in between the chassis and cable?

Anyway, it's been modded already and I got the motor and shaft so I might as well go ahead and use it.

By the way, what would the correct amp for this be?

Eric,
Yep--it's been "modded" ! You are correct, it has a plug in VC with wires--(BTW--check the value of that pot--the correct one is 25 k, later tube amps, that had motor provisions, used a 100k pot)
SHFA-3 would be the correct model. Ron Rich

OK, I'll check the Pot, if it's wrong what effect will it have on the performance? I'd prefer to have it work right than have remote volume.

Eric,
Just re-read your post---
No they would have used a PRVC-1 motor on it--it mounted to the "shoulder", on the metal surrounding the pot as shown in your photo.
You have a PRVC-2 or -3 motor, in the second photo. Ron Rich

Eric,
I dono--would guess it could tend to "upset the apple cart" ? Ron Rich

I just tried to measure the resistance of the Potentiometer, I got some confusing readings, I'll try again later tonight or tomorrow when I have more time, whoever did it just clipped the lugs off the old control and soldered them to the new one.

I realize from looking around on the Web that the motor I should have (or rather the motor that went with that Volume Control) was the PRVC1, however if you look closely whoever hacked it drilled a couple of mounting holes on the chassis to mount a PRVC2, the holes line up perfectly, that's why I thought I was buying the correct one on eBay. Should have looked more closely.

Ron,
I took the control out and measured it, it's 1.5 Meg across the outside terminals with taps at 1.0 Meg and 500k, both pots measure the same so I would guess they are good, just incorrect.
I found the manual for the Q100-Q160 (I thought I left it at work), it shows an SHFA2 amp in this model.
The specs for the SHFA2 are 25k each section, not 500k. So I guess it's probably not the correct pot for an SHFA1 either?