Crate BV120H , 500 plate volts, no current ?

[Jazz P Bass]

Good catch on that page 2 thing.
I was thinking that 85 watts from the wall was a tad low.
100-120 watts would seem more like it.

[gtrplayr1976]

Thanks guys. So I replaced the tubes ,and same thing I have no current reading on my bias probe. Jazz I have a meter , but I'm not sure what exactly the mains leads are. Could the bias pot be bad ? I see NO burned ,or hot spots anywhere. It's a very clean amp. What is the watts from the wall mean ,and how is this calculated. You guys know WAY too much

[gtrplayr1976]

OK...so I was doing some more poking around ,and I have found that F6 at the power xfmr seems to be bad. I have 7 VAC on one side ( J30 ) but not the other. Also I have NO voltage on J28 to ground. These are heater voltage ?

[g1]

Yes that is the heater fuse. Are your power tubes lit when in standby mode? Forget ground for now, you should measure 6 to 7 volts AC between J28 & J30.

[Jazz P Bass]

What is the watts from the wall mean ,and how is this calculated.

If you are not familiar with measuring current drain from the mains, pulease do not attempt it.
My all time favorite tool is the Killawatt.
Link: http://www.p3international.com/produ.../p4400-ce.html

[gtrplayr1976]

Yes that is the heater fuse. Are your power tubes lit when in standby mode? Forget ground for now, you should measure 6 to 7 volts AC between J28 & J30.

6.8 VAC between the two.

Noticed that R106 ,107 ,111 ,and 113 read about half what their value. Could be because they are still on the board ?

[gtrplayr1976]

If you are not familiar with measuring current drain from the mains, pulease do not attempt it.
My all time favorite tool is the Killawatt.
Link: P3 - Kill A Watt

thanks Jazz...I'm not afraid to check anything if I know what to connect to ,and what I'm looking for. I'm very aware of the potential.

[Jazz P Bass]

Alrghty then.
You have two "lines" going to the amp (sans ground wire).
The idea is to break (with a suitable adapter) one of the wires & insert, IN SERIES, an ammeter.
And there you have it.

[gtrplayr1976]

Alrghty then.
You have two "lines" going to the amp (sans ground wire).
The idea is to break (with a suitable adapter) one of the wires & insert, IN SERIES, an ammeter.
And there you have it.

The power lines in ? Gottcha...I'm guessin that's what the killawatt does ? Thanks Jazz

[g1]

OK...so I was doing some more poking around ,and I have found that F6 at the power xfmr seems to be bad. I have 7 VAC on one side ( J30 ) but not the other. Also I have NO voltage on J28 to ground. These are heater voltage ?

I think the SICAC (TR1) in the heater supply is shorted. The amp may hum/buzz a bit more than normal? I have never seen one used in a heater circuit before, personally I would just remove it.
http://www.el34world.com/Forum/index...;topic=12201.0

[gtrplayr1976]

I think the SICAC (TR1) in the heater supply is shorted. The amp may hum/buzz a bit more than normal? I have never seen one used in a heater circuit before, personally I would just remove it.
Print Page - Blue Voodoo 120 Noise Problem UPDATE: GOOD NEWS TO SHARE!

Thanks g-one . Would that be ok to do ? Why would they put it there if it really isn't needed ? I never got to hear this amp before it went out so I'm not sure about the hum/buzz.

Even if this is shorted ,would it cause the fuse to blow ? The fuse is on the other lead.

[g1]

No, it wouldn't cause the fuse to blow. More likely the fault that blew the fuse also blew the SIDAC. If TR1 is shorted it would explain why you see 0VAC at J28 to ground and 7VAC from J30 to ground. Normally you would see around 3.2VAC from either side to ground. You have resistors R106 and 107 to reference the heaters to ground, I think it would be fine to remove the SIDAC, in shorted condition it may cause hum issues. Don't know why they put it there, no one else uses them. If you are uncomfortable removing it, replace it. Maybe others here have further comments as to it's purpose, I think it is some kind of failsafe in case both R106 and R107 burn up, then you still have a ground reference for the heaters.
I'm a bit confused as to the timeline as far as when you had sound and when F6 blew. With F6 blown there would be no sound. It is possible that the original faulty output tube is causing the heater fuse to blow.

[gtrplayr1976]

No, it wouldn't cause the fuse to blow. More likely the fault that blew the fuse also blew the SIDAC. If TR1 is shorted it would explain why you see 0VAC at J28 to ground and 7VAC from J30 to ground. Normally you would see around 3.2VAC from either side to ground. You have resistors R106 and 107 to reference the heaters to ground, I think it would be fine to remove the SIDAC, in shorted condition it may cause hum issues. Don't know why they put it there, no one else uses them. If you are uncomfortable removing it, replace it. Maybe others here have further comments as to it's purpose, I think it is some kind of failsafe in case both R106 and R107 burn up, then you still have a ground reference for the heaters.
I'm a bit confused as to the timeline as far as when you had sound and when F6 blew. With F6 blown there would be no sound. It is possible that the original faulty output tube is causing the heater fuse to blow.

It was in the no sound condition when I got it. It had one cathode fuse blown also. I did snip the TR1 out. So now I need to get a 10 amp slo blo, and go from there I guess.

[g1]

It was in the no sound condition when I got it. It had one cathode fuse blown also. I did snip the TR1 out. So now I need to get a 10 amp slo blo, and go from there I guess.

Schematic shows 6.25A slo blo, was there a 10 in there? Is the board labelled as to the value?
Sorry I misunderstood as far as the no sound condition, I thought at some point you had sound, but I re-read the thread and I was mistaken. The no sound/no bias would be caused by F6 being blown. F3 blown would have removed V6 from the circuit. The tube that was in the V6 position is most likely bad and probably caused both fuses to blow. Continued use for testing may result in more blown fuses.
Once you get everything up and running you can decide whether to replace the SIDAC, hopefully someone will explain it's purpose. It may also have to do with protection in case windings in the power transformer get shorted together if the PT fails. Or maybe if there is a heater to cathode short and the cathode fuse blows.

Edit: It appears page 1 is the newer version, page 2 is the original. So heater fuse was changed from 10A to 6.25A (slow blow) and line draw bias method reduced from 1.3A to .8A (@120V).

[gtrplayr1976]

Schematic shows 6.25A slo blo, was there a 10 in there? Is the board labelled as to the value?
Sorry I misunderstood as far as the no sound condition, I thought at some point you had sound, but I re-read the thread and I was mistaken. The no sound/no bias would be caused by F6 being blown. F3 blown would have removed V6 from the circuit. The tube that was in the V6 position is most likely bad and probably caused both fuses to blow. Continued use for testing may result in more blown fuses.
Once you get everything up and running you can decide whether to replace the SIDAC, hopefully someone will explain it's purpose. It may also have to do with protection in case windings in the power transformer get shorted together if the PT fails. Or maybe if there is a heater to cathode short and the cathode fuse blows.

Edit: It appears page 1 is the newer version, page 2 is the original. So heater fuse was changed from 10A to 6.25A (slow blow) and line draw bias method reduced from 1.3A to .8A (@120V).

Yeah, the board is also labeled 6.25 ,but there was a 10A in there. From the link you sent it seems like the SIDAC isn't needed ,nor could anyone else explain it's purpose. So...it's history. I'll get a fuse ,and get it all back together ,and see if she fires up. Should be able to use the bias probe now.

Thanks g-one