New DSL40CR Bias Problem?

[bkhahn]

I recently picked up a new DSL40CR from Guitar Center and when I got home I opened it up to check the bias. Out of the box one tube was 12ma and the other was 13ma. After adjusting them as far up as I could while keeping the current matched I could only get up to 23.1ma. It was sold as new but was out of the box (still had all the manuals and foot pedal, just missing the outer box) so I have no reason to doubt it was new, although it may have been demo'd. I'm leaning towards trying to exchange the amp since it seems like even with the bias adjustment all the way up it's significantly below the recommended bias range. Thoughts/recommendations?

Thanks!

 

[Leonard Neemoil]

It's been a while since I've done this but I thought it was supposed to be measured in mV, not ma.

Someone more knowledgeable should be along shortly to confirm or correct.

Welcome to the forum.

 

[Rodical]

Take it back and have them order you another...

 

[anitoli]

Its gotta be those vietnamese transformers......

 

[EL34Norge]

Try changing you multimeter to 200mV instead of 200mA.
The DSL40C bias posts are 200mV on both of my multimeters.
I had a 40CR and can't remember if it's the same..

 

[Leonard Neemoil]

Try changing you multimeter to 200mV instead of 200mA.
The DSL40C bias posts are 200mV on both of my multimeters.
I had a 40CR and can't remember if it's the same..

See, I thought it was mV too...

 

[tmingle]

Also ensure that the speaker is connected to the correct jack

 

[Mitchell Pearrow]

I recently picked up a new DSL40CR from Guitar Center and when I got home I opened it up to check the bias. Out of the box one tube was 12ma and the other was 13ma. After adjusting them as far up as I could while keeping the current matched I could only get up to 23.1ma. It was sold as new but was out of the box (still had all the manuals and foot pedal, just missing the outer box) so I have no reason to doubt it was new, although it may have been demo'd. I'm leaning towards trying to exchange the amp since it seems like even with the bias adjustment all the way up it's significantly below the recommended bias range. Thoughts/recommendations?

Thanks!

Welcome to the Forum

 

[SkyMonkey]

Try again following this vid.

 

[KraftyBob]

Bias is in mA, however, it’s difficult (and not the safest) to measure because in order to measure amperage the meter needs to be in circuit - which means you need to break the circuit to insert the meter. But if you put a 1 ohm resistor from cathode to ground, per Ohms law 1 mA = 1 mV, and since voltage is measured across the circuit it’s easier and safer to do. As others have said make sure your meter is on the mV setting as that’s what the bias points on the amp are configured for.

The images below show how amperage and voltage are measured in a circuit.

Measuring amperage


Measuring voltage

 

[bkhahn]

Thanks everyone - did some more testing and the tubes are still super cold even when measuring mV and following the instructions from the Oldguyjammin video above. I'll give the store a call and see what they want to do about it. Appreciate the help!