#1
I don't know for sure whether this is really a problem or not but last night I had turned my X100B on into standby and ended up getting distracted with something else. I came back about 30 minutes later and noticed that the tubes were not hot or even warm for that matter. So I checked the voltage for the heater filaments and both wires read 2.7 volts. I measured where the wires connect to the board and the heater pins on each power tube as well and got the same reading everywhere. Is this too low? I see on other amp schematics values around 6.3 or 6.9 volts for the heaters. How much voltage should I be getting for these heaters? Whatever the value is, should that value be per wire or a sum of the two?

If anyone could offer some advice it would be greatly appreciated.
Guitar:
Dean Vendetta 3 - Dave Mustaine Livewires

Amplifier
Carvin X100B - Bias Mod - Tungsol 12AX7's - JJ KT77's

I have built the most badass 212 that puts all others to shame
#3
Quote by end_citizen
Set your multimeter to AC voltage. Put one contact on one of the heater wires, and the other contact goes on the other heater wire.


Did that and it didn't give me anything. I only got a reading when I took the measurement from ground and that was the 2.7 volts per wire

Edit: Link to schematic if anyone needs it.
Guitar:
Dean Vendetta 3 - Dave Mustaine Livewires

Amplifier
Carvin X100B - Bias Mod - Tungsol 12AX7's - JJ KT77's

I have built the most badass 212 that puts all others to shame
Last edited by MeanwiththeDean at Jul 9, 2009,
#4
You should get around 6.3V AC when you measure from one heater to the other. Put one of your DMM's probes on pin 9 and the other on 4/5 (4 and 5 are connected).
#5
That's weird that you didn't get any reading. I don't know if you have the reissue or not, but here is the old schematic for the original:

http://schematicheaven.com/newamps/carvin_x_series.pdf

It doesn't rectify the heater voltage, so it should read about 6v AC across the two.

Side note: I love that amp. I nearly bought one just for the clean channel. I'd never heard a clean amp I liked so much. I might get one in the future.
#6
sounds like you're on the 240v tap for the PT primary. but how could that happen?
Meadows
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#7
No I don't have the re-issue. I have the one from the transitional period when they were swapping from 6L6 to EL34. Yes, the clean channel is amazing. I thought it was good before I re-capped it...

When I get home I will re-measure across the two wires and pins and see what I get.
Guitar:
Dean Vendetta 3 - Dave Mustaine Livewires

Amplifier
Carvin X100B - Bias Mod - Tungsol 12AX7's - JJ KT77's

I have built the most badass 212 that puts all others to shame
#8
Quote by MeanwiththeDean
No I don't have the re-issue. I have the one from the transitional period when they were swapping from 6L6 to EL34. Yes, the clean channel is amazing. I thought it was good before I re-capped it...

When I get home I will re-measure across the two wires and pins and see what I get.


Yeah, the 6.3V is from one side of the heater to the other, so you're measuring from 4/5 to 9. 2.7 V would imply 5.4V from 4/5 to 9
Quote by kcdakrt
DLrocket89 makes my ug experience better!


Member of the official GB&C "Who to Listen to" list

Kit Amp Building Tutorial
#9
Thank you for your help guys. I took the readings again last night as instructed and came up with 6.1 volts at the preamp pins and where the heater filaments attach to the board. Not sure why I didn't get that the first time around but it doesn't matter.

Thanks again.
Guitar:
Dean Vendetta 3 - Dave Mustaine Livewires

Amplifier
Carvin X100B - Bias Mod - Tungsol 12AX7's - JJ KT77's

I have built the most badass 212 that puts all others to shame
#10
Quote by MeanwiththeDean
Thank you for your help guys. I took the readings again last night as instructed and came up with 6.1 volts at the preamp pins and where the heater filaments attach to the board. Not sure why I didn't get that the first time around but it doesn't matter.

Thanks again.


Yeahup, you're all good.
Quote by kcdakrt
DLrocket89 makes my ug experience better!


Member of the official GB&C "Who to Listen to" list

Kit Amp Building Tutorial