I just got a 220, and when i turn it off the plate voltage meter shows 1kv in hv setting, and fan is still running?? can use some help??
-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
heathkit sb220
- Thread starter Number15
- Start date
Umm, two possibilities:
1) Wiring error, or
2) Bad power switch. The power switch has two poles, one to turn off each side of the 240 Volt line. Sometimes one side ONLY will become spot-welded together. Only one side will turn off when this happens.
If it's bad you'll end up having to contrive a substitute, like putting a small metal plate over the original hole, with a toggle switch mounted in a hole at its center. Just make sure that it's a 20-Amp rated switch. A smaller one may fail sooner. The turn-on surge in that amplifier is pretty mean.
73
1) Wiring error, or
2) Bad power switch. The power switch has two poles, one to turn off each side of the 240 Volt line. Sometimes one side ONLY will become spot-welded together. Only one side will turn off when this happens.
If it's bad you'll end up having to contrive a substitute, like putting a small metal plate over the original hole, with a toggle switch mounted in a hole at its center. Just make sure that it's a 20-Amp rated switch. A smaller one may fail sooner. The turn-on surge in that amplifier is pretty mean.
73
Thanks for the info it was wired for 220 and it was working fine then i wired it to 110 and thats when it stoped working right. Thanks again nomad.
Hey, you're welcome.
But I can't resist mentioning what a bad idea it is to run the SB-220 from a 120-Volt circuit.
For the most part, if you keep it on the "CW/Tune" side, this prevents it from drawing excess current from the 120-Volt circuit. You'll have to settle for about half the power output you could expect from a 240-Volt circuit. Push it too hard, and you'll see the yellow-white light from the filaments dim and 'yellow' when you drive it too hard on 120 Volts. This will reduce the life of the tubes, since those filaments need to be running at full temperature to obtain normal service life.
Building codes forbid using wire large enough to prevent this to feed a 120-Volt outlet circuit. Even if the 240-Volt circuit has the same size wire feeding it, the amplifier draws half the current from a 240-Volt circuit. This reduces the "voltage drop" problem all by itself. Besides, losing, for example, 5 Volts at the outlet under load has HALF the effect on the tubes' filaments when running from 240 Volts as it has on a 120-Volt setup.
This is the basic "double whammy" that necessitates turning down the drive to prevent tube damage on a 120-Volt circuit.
Glad to hear it was a simple problem. Well, so long as you have a 240-Volt circuit to run it from.
73
But I can't resist mentioning what a bad idea it is to run the SB-220 from a 120-Volt circuit.
For the most part, if you keep it on the "CW/Tune" side, this prevents it from drawing excess current from the 120-Volt circuit. You'll have to settle for about half the power output you could expect from a 240-Volt circuit. Push it too hard, and you'll see the yellow-white light from the filaments dim and 'yellow' when you drive it too hard on 120 Volts. This will reduce the life of the tubes, since those filaments need to be running at full temperature to obtain normal service life.
Building codes forbid using wire large enough to prevent this to feed a 120-Volt outlet circuit. Even if the 240-Volt circuit has the same size wire feeding it, the amplifier draws half the current from a 240-Volt circuit. This reduces the "voltage drop" problem all by itself. Besides, losing, for example, 5 Volts at the outlet under load has HALF the effect on the tubes' filaments when running from 240 Volts as it has on a 120-Volt setup.
This is the basic "double whammy" that necessitates turning down the drive to prevent tube damage on a 120-Volt circuit.
Glad to hear it was a simple problem. Well, so long as you have a 240-Volt circuit to run it from.
73
Wouldn't you expect to see most of the normal voltage even on a 110 volt circuit? At least when there was no load? Sounds like the transformer or the plug is still wired wrong if it only shows 1000 volts.
Just wondering because I recently had a Henry do the same thing and it had a 110 volt plug but was wired for 220. Come to find out the guy's outlet is wired like that. Not sure if he ever fixed it but I hope he never plugs a radio in to that circuit by accident.
Just wondering because I recently had a Henry do the same thing and it had a 110 volt plug but was wired for 220. Come to find out the guy's outlet is wired like that. Not sure if he ever fixed it but I hope he never plugs a radio in to that circuit by accident.
Not sure about the 220, but a great many tube-type amplifiers will show HV on the plate voltmeter for a significant time after it's been switched off. The reading should more or less slowly decrease and approach zero, depending on the filter capacitors in the power supply and the value of the bleeder resistor across the B+. If the reading remains essentially unchanged for several minutes, I'd check the bleeder (after carefully discharging the capacitors).
One of the mods done was a filter capacitor block replacement, and was running fine at 220v and when i changed it to 110v, then it showed 1kv one the plate voltage meter, I live near sacramento CA, and im trying to find a good tech to look at the sb220 but no luck yet, Thanks for all your help.
Thanks i will look, at putting it back to 220. Funny thing was when it was on 110, it showed 1kv and fan ran, but lights on meter went off. anyway Thanks for the help. #15
That's what leads me to suspect a wiring error. If the filament transformer is off when you flip the switch, the H.V. transformer (and fan) also should be off, as well. The only way to run the HV/fan (apparently at half voltage) and NOT the filament transformer (meter lights) is to wire it wrong, I think.
Or, if some wiring quirk were to (in effect) place the primary of the HV transformer in series with the primary of the small transformer, you might get this kind of symptom, maybe?
An error that boogers up your 120-Volt capability won't necessarily cause trouble when jumpered for 240 Volts.
73
Or, if some wiring quirk were to (in effect) place the primary of the HV transformer in series with the primary of the small transformer, you might get this kind of symptom, maybe?
An error that boogers up your 120-Volt capability won't necessarily cause trouble when jumpered for 240 Volts.
73
Thanks, Nomad i will trace all the wires and look at the book to see if i can find problem, Kevin.