So I built a pair of the Uniamps designed by Pete Millett, They gave me fits with a low frequency oscillation but Pete helped me fix it. I only used them for about 40 hours when one of the Svetlana KT88s died, It must have been a leak in one of the pins all of the silver getter was gone. So they have set in the closet for several years until I decided to just buy a quad set of JJs to replace them. I have a variac should I bring up the voltage slow to give the caps (black gates) time to reform? How long and at what voltage would be good, I will either put a speaker or 8 ohm load resistors on it when I do this.
Thanks for your help.
Bill
By the way I will be open to offers for the 3 tubes, it is a shame they are much better than the JJs ,
Bill
Thanks for your help.
Bill
By the way I will be open to offers for the 3 tubes, it is a shame they are much better than the JJs ,
Bill
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I would just plug it in and go. I live dangerously...
Really though, a few years isn't that long. I would expect a store-bought unit to power up as normal after that time dormant.
I also have a Belcor tube amp under my bed that has run once in 10 years. I wouldn't think twice about just plugging it in and using it.
Really though, a few years isn't that long. I would expect a store-bought unit to power up as normal after that time dormant.
I also have a Belcor tube amp under my bed that has run once in 10 years. I wouldn't think twice about just plugging it in and using it.
It does have a tube rectifier, (dual monos) and one of those had most of its getter gone I have a set of spares I will use.
Thus I suggest run, say, an hour with the rectifier removed, so humidity goes from mains tranformer, and carhodes "cleans".
Then, try to get a light bulb of the filament kind, if 220/240V better (no led nor fluorescent, wire filament as Edison did). Try to cut the cathode of the rectifier to first electrolytic or the centertapped secondary from chassis ground, and wire a large resistor, say, 100Kohm 5W in this wire. Thus, energize the device this time with amplifier tubes removed (take a photo or make a diagram so you can re-put them in each socket). Put a DMM in the +B and observe if slowly the voltage is increasing. This is to reform lytics. Once it got, say, 80% of normal voltage, turn off power and let the voltage reduce to low level, say, 50V. If you find one or more lytics got hot, don't try to use it and replace them with new ones.
Repeat this procedure 4 o 5 times reaching normal voltages whilst observing temperature and or smell.
If all go wright, replace the resistor with the lamp. 100W suffices. Replace all tubes and run the set while observe the bulb. If suddenly it goes bright, is because the electronics is faulted. No music but a small load, say, a 100R resitor.
If all is good, remove bulb and replace the connection and the amp is safety to be used.
Then, try to get a light bulb of the filament kind, if 220/240V better (no led nor fluorescent, wire filament as Edison did). Try to cut the cathode of the rectifier to first electrolytic or the centertapped secondary from chassis ground, and wire a large resistor, say, 100Kohm 5W in this wire. Thus, energize the device this time with amplifier tubes removed (take a photo or make a diagram so you can re-put them in each socket). Put a DMM in the +B and observe if slowly the voltage is increasing. This is to reform lytics. Once it got, say, 80% of normal voltage, turn off power and let the voltage reduce to low level, say, 50V. If you find one or more lytics got hot, don't try to use it and replace them with new ones.
Repeat this procedure 4 o 5 times reaching normal voltages whilst observing temperature and or smell.
If all go wright, replace the resistor with the lamp. 100W suffices. Replace all tubes and run the set while observe the bulb. If suddenly it goes bright, is because the electronics is faulted. No music but a small load, say, a 100R resitor.
If all is good, remove bulb and replace the connection and the amp is safety to be used.
Bringing up voltage slowly to a tube amp is not a good idea. This way you could get too low bias voltage and overheat the output tubes if fixed bias is used in that amp.
Regards,
Regards,
Reseat the tubes to remove any corrosion on the pins and sockets. If it was stored inside hook up speakers you don’t care about and turn it on. Let it run playing music for an hour or more. If all is good put it into service.
This is what I was concerned about,I think they were not stored too long. I do have some deoxidizer spray I will clean the sockets. The uniamp is built on a pc board so it is difficult to pull out parts to isolate the caps.
Thanks
Bill