Power and lights but no sound?

[BrianW]

I recently acquired an electronic organ for free off the street. I am quite excited about playing it, however I plug it in and no sound comes out. There are lights on the front by the power switch and in back from each of the tubes, the fuse is intact. There is not even a vibrating or oscillating sound, which I remember coming out of other electronic organs. There is no obvious brand name or year visible, I would be happy to send a picture. Is this something easily fixable, or am I in over my head? Are there a couple of things that I should check first? I have very little knowledge of the workings of electronic organs, thanks for helping out!
Brian

[Jan Girardot]

If it is a Thomas, the earphone-speaker switch up under the keyboard deck (the part that hangs out over your knees when playing) may be in the "off" position. Or, there may be an earphone plug stuck in the earphone jack. Give it a look and let us know.

. . . Jan
the OrganGrinder

[BrianW]

If it is a Thomas, the earphone-speaker switch up under the keyboard deck (the part that hangs out over your knees when playing) may be in the "off" position. Or, there may be an earphone plug stuck in the earphone jack. Give it a look and let us know.

. . . Jan
the OrganGrinder

Thanks Jan, However this is not the case. On closer inspection the organ I found is a Lowrey DS from somewhere between 1958 and 1965 or so. It has a bunch of vacuum tubes, which I plan to test at a local electronics store tomorrow, especially the ones connected to the main power supply. I located a manual from a similar year Lowrey and ran through the troubleshooting guide (power switch is on, one of the white stops is on, volume pedal depressed, etc.) which bore no fruit. A tip i received from a consultation with an organ repair guy was that the resistors in the power supply of these organs will commonly fail. Is this a project I could undertake myself? I have some knowledge of electronics. Any other tips? If anyone is in the San Francisco area I would buy you a sixer to take a look at this thing!
Thanks!
Brian

[Hamman]

Resistors? More like electrolytic capacitors drying out and or shorting out in the PS. This is where Indianajo will probably jump in

[OrgansR4Me]

If you are comfortable with soldering you should have no problems. Keep careful notes on the polarity of caps. If possible take a photo before you detach parts. If your work should be interupted you won't have to rely on memory. Then work one or two parts at a time so as to not be confused which new part isn't working. I'm not saying the first part added will finish the job but if you do 5 things at once ... where do you start troubleshooting the repair? See what I mean. I recently replaced a couple of small caps on my Hammond and since it was only two I did both. Glad to say the amp started right up.

IndianaJo's post previously referred to can be found in our archives under the search "capacitor"

[jimmywilliams]

If you have the service manualwith the schematics, that is vital. If you do not have the exact one Jan might.
Did you try the easy stuff, like seeing if the speaker was bad? And, making sure the expression pedal was fully depressed? You could have a bad peaker, bad expression pedal circuitry, or no power getting to the amplifier stages.

[Jan Girardot]

Brian, the resistor tip is a very valid one. The early Lowrey tube organs used an interesting but problematic power resistor called a Candohm* of various values in the power supply section. If you feel comfortable when working around some rather lethal voltages, you should be able to narrow down the bad resistor(s) with a voltmeter. They are screwed directly to the inside of the steel chassis, close to the power transformer.
When you track down the bad one, I can supply a suitable and reliable replacement.

Get the voltages up and running before rushing off to get new electrolytic filter condensors (capacitors).

. . . Jan
the OrganGrinder
* "ohms in a can", get it?

[BrianW]

Thanks for all the good advice. As far as I know, I have tried all the obvious stuff. I spoke with my neighbor, who said HE put the organ on the street! He was playing it one day and it made a pop, then stopped working. Based on reading old threads, this sounds like a classic presentation of a blown electrolytic capacitor. Should I go ahead with the capacitor, or entertain other options? From what I can tell, its a sprague multitap aluminum capacitor. I am having trouble finding a new one online, can someone recommend a resource? I saw that I can sting together individual capacitors to serve the same purpose, any tips on this? My buddy is bringing over a voltometer tomorrow, so that may help detect a bad resistor. I have a basic knowledge of electronics, but not of vacuum tubes. I read some of IndianaJo's old posts about safety, but one of the links was no longer functioning. Can someone provide a good resource on basic safety/vacuum tubes? I basically just keep it unplugged. Thanks for all the tips, can't wait to start playing this thing!
Brian

[Guitarbro]

If you can read the values off of the capacitor I can help point you in the direction of replacements.

[BrianW]

Thanks, that would be helpful. It reads:
Sprague
998-126543
40-500 DC [followed by a symbol that looks like a D on its side)
30-450 DC [followed by a square]
30-450 DC [followed by a triangle]
50-150 DC
CAN.COM.NEG
D13471 908-J
Whats the best way to get this thing out and test it?
Brian