new liver pool build not passing the light bulb limiter test
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liver pool
So Sorry for all the dumb questions
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martin manning
- Posts: 14308
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: new liver pool build not passing the light bulb limiter test
Unplugged, power and standby off.
Fuses don't have a "reverse," except that it's best to run the hot line wire to the center terminal on the fuse holder to minimize the chance of someone getting shocked.
There are two PT grounds, center taps for the filament (heater) winding and the high-voltage winding. They can both go to the same point, usually the same place as the ground for the first filter, by the AC power inlet in your case.
Something is shorted to ground, or you have a short across one of the PT windings. That could be a wiring error or less likely, shorted diodes or filter caps. If the resistance measurements on the standby switch look good, You could disconnect the heater wires from the PT and try the lightbulb test again.
Fuses don't have a "reverse," except that it's best to run the hot line wire to the center terminal on the fuse holder to minimize the chance of someone getting shocked.
There are two PT grounds, center taps for the filament (heater) winding and the high-voltage winding. They can both go to the same point, usually the same place as the ground for the first filter, by the AC power inlet in your case.
Something is shorted to ground, or you have a short across one of the PT windings. That could be a wiring error or less likely, shorted diodes or filter caps. If the resistance measurements on the standby switch look good, You could disconnect the heater wires from the PT and try the lightbulb test again.
liver pool
Thanks everyone took it to a tech today had input jack wired wrong now I have to find a way to tame the gain barely cracked the thing is crazy
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geetarpicker
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- Location: Nashville, TN
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Re: new liver pool build not passing the light bulb limiter test
Try to find a better taper volume pot before you start modding the amp for lower gain. My '85 wreck 1meg clarostat volume pot is only at a mere 100k @ 1/2 rotation. The taper is one of the details Ken got right and it will be worth looking into this a clone even if it means using NOS pots.
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martin manning
- Posts: 14308
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: new liver pool build not passing the light bulb limiter test
harris51, sounds like you didn't have a short after all? Maybe you were misinterpreting the indication from the bulb limiter?
The expected behavior is for the bulb to light brightly when you first turn on the AC power, then dim to maybe 10% of full brightness after 10-20 seconds as the reservoir capacitor(s) charge. If you then turn the standby on you should se a similar sequence, but the bulb will be incrementally brighter at the end due to the additional current draw with the HV applied to the tubes (idle current). A short is indicated by the bulb coming on brightly and not dimming after a few seconds. That is a "fail" of the bulb test.
Hang around and keep asking questions.
Glen, I think a lot of current-production audio taper pots are 10% of max resistance at 50% rotation (I've checked Alphas, Bourns, CTS), but they seem to jump in resistance off the CCW stop, and that is what causes the undesirable volume change.
The expected behavior is for the bulb to light brightly when you first turn on the AC power, then dim to maybe 10% of full brightness after 10-20 seconds as the reservoir capacitor(s) charge. If you then turn the standby on you should se a similar sequence, but the bulb will be incrementally brighter at the end due to the additional current draw with the HV applied to the tubes (idle current). A short is indicated by the bulb coming on brightly and not dimming after a few seconds. That is a "fail" of the bulb test.
Hang around and keep asking questions.
Glen, I think a lot of current-production audio taper pots are 10% of max resistance at 50% rotation (I've checked Alphas, Bourns, CTS), but they seem to jump in resistance off the CCW stop, and that is what causes the undesirable volume change.
liver pool
anybody know where I can get one of these awesome pots with the longer taper?