Having some issues with biasing a Hot Rod Deluxe. The bias test point reads an open circuit (0.L) when using my DMM on mV.
D3 diode test good
D4 R3000 diode test good
D5 R3000 diode test good
470 plate resistors test good
1.5K grid reistors test good
Plate voltage, screen voltage, negative grid voltage are good.
Could anyone take a few moments and help me out with this one?
I'd appreciate it.
Tom
Fender Hot Rod Deluxe Bias Problem
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thewinterroom
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Fender Hot Rod Deluxe Bias Problem
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Re: Fender Hot Rod Deluxe Bias Problem
O.L. more likely means over load.
Maybe R66 is open circuit?
I doubt that D3 would measure correctly if it was really in parallel with a 1 ohm resistor.
Maybe R66 is open circuit?
I doubt that D3 would measure correctly if it was really in parallel with a 1 ohm resistor.
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thewinterroom
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Solder Connections
I forgot to mention all solder connections on the pins of all tubes are good.
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thewinterroom
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R66
R66 1ohm 1W resistor is good. I threw in a new one for good measure.
Still reading OL
Still reading OL
Re: Fender Hot Rod Deluxe Bias Problem
Are you saying the amp is playing properly?
If yes, then you're just having an issue finding the cathode voltage with your DMM. R66 is the cathode resistor. One end is grounded, so you'll read zero volts there. The other end is attached to pins 8 of the power tubes, and you should read Fender's recommended 60mV there, WRG.
If yes, then you're just having an issue finding the cathode voltage with your DMM. R66 is the cathode resistor. One end is grounded, so you'll read zero volts there. The other end is attached to pins 8 of the power tubes, and you should read Fender's recommended 60mV there, WRG.
I build and repair tube amps. http://amps.monkeymatic.com
Re: Fender Hot Rod Deluxe Bias Problem
Checked the meter battery?
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Stevem
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Re: Fender Hot Rod Deluxe Bias Problem
Did you blow a fuse in the meter?
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Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Fender Hot Rod Deluxe Bias Problem
Fuse should only affect measuring current. I doubt there's a fuse on the mV scale.