Picked up a couple of new pieces to restore

[cademan]

Mike, if you see one of those yellow paper capacitors connected to the plate (pin 3) of the 6V6 tubes, In one of my sams photofact folders of a spartan unit, it is whats known as a tone compensation capacitor. It's a .0022 or .01 cap @600 volts, and it is what you heard pop, then no sound.

You can simply remove it and you will get your sound back. Had one of these go out on an old spartan AM/78 record player I fixed for a woman. Of course (yeah, we know) a complete recap is in order, but if you want to hear it temporarely, remove it!

 

[mashaffer]

Thanks Cademan, I saw that interesting tone control on the schematic (took a while to recognize what it was). I just ran up and took a quick look and there are a couple of grungy brown 600V caps that seem to be the tone control caps. One (.02uF) goes from pin 3 of one output tube to the CT of the tone control and another (.002uF) goes from one of the plates to pin 1 on the other. I didn't realize that this was a NC pin so I neglected to trace what else was connected. I suspect that this one is the one between the plates. Both were discolored and waxy but neither looked like it had "exploded" would be interesting to put them on the meter.

What I may do is check the tubes for obvious shorts with DMM, replace the paper and 'lytics and bring it up on the lightbulb limiter and see what I get.

mike

 

[cademan]

When it "pops" through the speaker, the cap hasn't exploded, it is just shorted inside. The one I was talking about that I fixed for this lady, needed a new output transformer. After I fixed it, it would work fine at first, then after about a minute or so, POP, and then nothing. Fortunately, this one had a schematic glued to the inside of the cabinet.

After studying it, it didn't make sense to have a cap tied to each plate off of the 6V6s. If the cap went bad (shorted), it just tied the two plates (pins 3) together.

When I removed it, the unit worked like a charm and never made the "POP" sound ever again!

 

[mashaffer]

Oh, just one more thing. Did removing the cap totally defeat the tone control or just change the overall voicing?

mike

 

[cademan]

It actually made it sound more richer, fuller! Your tone control knob will still work and do what its supposed to do! I never got a chance to hear it before I replaced the output transformer because she said her son tried fixing it, but had no luck. Get this, he tried fixing it with and old choke coil and had only two wires coming out of it. LOL. Guess he didn't know what he was doing.

After I fixed it, it sounded wonderful for a 1948 model. and I didn't want to give it back! It had AM, FM and a 78 Phonograph. The FM sounded awsome and filled my living room with clean, full range bass and treble. An amazing 12inch field coil speaker.

 

[mashaffer]

Do you think that the bad cap took out the OPT?

mike

 

[cademan]

I don't think so! When it shorted, it just tied the two plates together. It just won't let any voltage to the output transformer!

I'll post a pic of the schematic of the one I worked on so you can see how it was used in the circuit. Its just a little bit different from the one you posted, but I think it would be the same results.

 

[cademan]

Take a look at capacitor #9, connected to the plates (pins #3) of the 6K6 tubes.

 

[mashaffer]

Yep, a little bit different but results would be similar I bet. Incidentally I checked all of the values on the paper caps and they are almost all .05uf except for the .02u and .002u for the tone caps. I bet changing to .022u and .0022u would not change the response much.

I also measured a few resistors and several were right on. one of the 3.3M resistors however measured 4.2M. Not sure if that is a problem but I have a lot of slavaged CC resistors so instead of buying new I could just cherry pick for proper values from my stash. For a notsohifi like this that may be good enough.

mike

mike

 

[cademan]

Just disconnect or remove that cap I mentioned, and I'll guarantee you will get sound!

 

[mashaffer]

You are probably right but I already started digging in to the recap (had to dig some stuff out to check a value. The schematic that I have is such a poor scan that I can't see the values listed in the charts. When I get everything in I will try it with and without that cap to see what the difference in sound is. Really appreciate your help and insight.

mike

 

[mashaffer]

Well I couldn't resist any longer so I fired up the Hammond. I watched, listened, and sniffed carefully with my finger on the switch. Nothing bad happened so I played around a little bit. Surprisingly there was very little in the way of untoward electronic noise or hum. At first only the pedals were working but I worked the tabs and sliders a bit and as it loosened up it got to the point that virtually everything was working. The tab just to the right of the lower manual drawbars tab is broken off and appears to be in the off position. I think it will clean up pretty nice.

I downloaded the L100 service manual so I should be able to figure it all out. I have an unused guitar combo cabinet (12" driver hole) so I am kicking around the idea of adapting the amps so that I can mix in a couple aux inputs for other keyboards and install the amps and the reverb in the combo cabinet with the expression pedal set up for remote connection. Hopefully I could then do a chop job and mount the generators in a separate unit for portable use.

Of course I would have to put in outputs for a leslie and subwoofer.

mike

 

[radiotvnut]

On the Sparton, I'd check the power transformer before I recapped it. Just pull all the tubes and turn the set on. Use your voltmeter to check the HV winding, the filament winding, and the rectifier tube filament winding. If the voltages check OK, leave it plugged in for a few minutes. If the transformer runs cool, does not stink, etc.; it will likely be fine. I think you'll have a nice performer once you get it going.

The GE stereo is from around '63-'64. I had a GE suitcase record player from that time period that used the same VM built TT. I will warn you that some GE stuff from that period can be a nightmare to work on.

I don't know much about that organ. I do have a friend that works on organs; but, he does better with the solid state models. He's getting better with the tube models; but, he still calls on me to test tubes and answer questions about caps, etc. From what he says, there are still plenty of churches that still have tube type organs in service.

 

[amptramp]

The screen-grid inverter was used by a number of manufacturers (and is used on my Philco 42-395) but never really did the job properly. There was a considerable variation in screen grid voltage gain and this tended to change as the tubes aged, so a proper inversion with the bottom control grid seeing the inverse of the upper stage drive voltage could never really be obtained. The screen voltage does not necessarily follow the plate voltage linearly, so the distortion from this type of inversion is noticeable.

Some manufacturers used a resistor in series with the bottom screen and the upper tube screen resistor to approximate a current source and provide some current sharing between both screens so that the distortion would be reduced.

You could not use a common unbypassed cathode resistor for both output tubes or you would get an astable multivibrator - not what you want in an amplifier.

Another variation on this was to use a transformer tap like an ultralinear tap on the output transformer in place of the upper screen as a source which worked unless the gain was sufficient to cause the whole stage to behave as an oscillator. There is something like 6 db margin between working properly and oscillating, so output tubes had to be matched for gain and replaced in pairs.

 

[Mick AV-8]

Not sure but didn't they use a Harmond in "The Doors" ?
Play some light my fire..but make sure it doesn't generate smoke...

 

[Kingfisher]

Not sure but didn't they use a Harmond in "The Doors" ?
Play some light my fire..but make sure it doesn't generate smoke...

Ray Manzarek played combo organs until "The Soft Parade" album in 1969, when he started using a Hammond C-3 along with the Combos (Vox, Gibson-Kalamazoo) and Fender-Rhodes electric piano. No Hammond in Light my Fire.

 

[Kingfisher]

Well I couldn't resist any longer so I fired up the Hammond. I watched, listened, and sniffed carefully with my finger on the switch. Nothing bad happened so I played around a little bit. Surprisingly there was very little in the way of untoward electronic noise or hum. At first only the pedals were working but I worked the tabs and sliders a bit and as it loosened up it got to the point that virtually everything was working. The tab just to the right of the lower manual drawbars tab is broken off and appears to be in the off position. I think it will clean up pretty nice.

I downloaded the L100 service manual so I should be able to figure it all out. I have an unused guitar combo cabinet (12" driver hole) so I am kicking around the idea of adapting the amps so that I can mix in a couple aux inputs for other keyboards and install the amps and the reverb in the combo cabinet with the expression pedal set up for remote connection. Hopefully I could then do a chop job and mount the generators in a separate unit for portable use.

Of course I would have to put in outputs for a leslie and subwoofer.

mike

Mike, yours is an earlier model Hammond from about '61-'63. Lots of wax caps on that tone generator. If you want to hook up a Leslie you need to buy a connector kit and know which type of Leslie you want to use. I suppose you could build one from scratch, but there are many different types of Leslies with multiple speeds, multiple channels, SS or tube, one or two rotors, etc. I paid $150 for my 6122 (6-pin, Leslie 122) connector kit, and that was 10 years ago. Cables can be pricey as well. Good luck and know your pin-outs.

 

[mashaffer]

Well I do have these on hand...

Small leslie out of (I think) a SS hammond spinet.

And a larger unit from a Wurlitzer Centura. Sorry I don't have a pic of the front side.

Unfortunately these spinets don't seem to have much value. I am going to run out of room for organs if I keep picking up every freebie I find.

mike

 

[Kingfisher]

Well I do have these on hand...

Small leslie out of (I think) a SS hammond spinet.

Leslie sold those as a standalone cabinet, It's called a Model 130. There are other single-rotor SS Leslies from the the same time period ('70's) but I don't remember what they are. Maryland Organ Service had a database somewhere online. Every model ever made. Hopefully they didn't take the site down.

And a larger unit from a Wurlitzer Centura. Sorry I don't have a pic of the front side.

Unfortunately these spinets don't seem to have much value. I am going to run out of room for organs if I keep picking up every freebie I find.

mike

I envy you. Tube organs of all kinds are all gone around here. I never see them anymore. Either somebody is buying them up quickly, or their not showing up at thrift shops, CL, estate sales, etc.

 

[soundmotor]

I am actually seriously considering refurbishing the workings and then if I like it giving it a chop job. (http://en.wikipedia.org/wiki/Hammond_organ#Chop_organ) I figure most of what I invest in getting it up to speed would still be useful if I eventually decide to use it as a donor.

mike

I worked with the keyboardist from a local Boston band and he chopped his Hammond. It wasn't like yours, it was bigger. It took him about month, a couple hours each evening afterwork sporadically, but he did it and gigs with it now.