AmpTalk.com

[k1ll flanders]

as soon as I got the amp home I hooked it up to my 2x12 cab and it had the tone I have searched 15 years for. I had a good jam session a few days later with it every one was envious. I plugged it in yesterday only to hear nothing at all. The tubes are old but still glow. There is no ohms rating on the amp and my cab is 4ohms. can anyone tell me how to check the impedance of the amp and any suggestions to get it working would be nice also!

[zappa jr.]

Sounds like a possible blown rectifier tube, however it could be any of a number of things from the obvious fuses,cords,broken or loose wires to tubes or capacitors.
Tubes can still glow but have one blown plate,hence be dead and not output any sound.
when you turned it on was it dead silent (possible rectifier)or did you hear some fuzzy distortion fading to quiet?(possible preamp/power tube/s)
Have someone check your tubes if possible...reasonably inexpensive,
no more than a buck or two each.
rectifier tubes are USUALLY the cause of sudden/complete sound loss in a tube amp.
Go through as many of the checks as you can yourself before resorting to throwing money at the problem.
If you do have to re-tube I Highly reccomend EBAY for your tubes...
generally half of retail price. Just make sure you buy tubes with actual test #'s instead of just saying "tested good" as these can barely test in the good range and still be sold as "GOOD"
also, when re-tubing, Brand and Style of tube is EVERYTHING to your sound. make sure to replace w/same to keep that sound you found.
minor differences in style such as: 6L6, 6L6GC, 6L6GB can DRASTICALLY alter your sound.
As for impedance on the amp, this is what I found online...
"There is no practical way to measure the output impedance of an amplifier. Read the value off the back of the machine, or look it up in manufacturer's literature.
Note: Even if you could measure the impedance of your amplifier, you wouldn't want to do so. Maximum power is delivered to the load if the source and load have the same impedance. But when this is true, both the load and the source are dissipating the same amount of power. So, if you want to send 100 Watts out to the speakers, you must generate 200 Watts, half of which is wasted as heat in the amplifier. The trick is to have a carefully calculated impedance mismatch, so that most of the power goes out the speakers. This is taken into account by the designers of the amplifier. So an amp that says "8 Ohms" doesn't necessarily have an 8 Ohm output. That's just that the amplifier was designed to drive an 8 Ohm load. If it helps, think of an amp's rating as the "target impedance". "
So i would guess try Google and enter model # and name.
I found this page and it may help:
http://www.harmony-central.com/Guitar/Data/Lectrolab/
Keep us informed...
Zappa, Jr

[k1ll flanders]

The blown rectifier tube theory sounds about right. As for impedance value there is absolutly nothing on the back, its a peg board backing that has 2 speaker outputs and that is all. When you take the back off its written with a pen, wich wires are ground. Lectrolab went out of business in the late 60's and google found nothing for the model(s-950) I have. wich also isnt on harmony central either. Thanx for the help I'll check the tubes and go from there. Thanx again for the info...
Kill Flanders