Add choke to blues junior (mexico)

[bluestom50]

Can anyone be so kind to tell me the location where to remove resistor and wire in a mm choke in my blues junior, thanks, tom

[sgelectric]

Schematic for Blues Jr:

http://www.webphix.com/schematic%20h...s/blues_jr.pdf

SG

[Jazz P Bass]

Try this read: Chokes

[52 Bill]

The simple answer is to replace R32 2K2 2 watt with it. That's the first dropping resistor in the power supply and the place that a choke would normally be found.

[sgelectric]

Is it correct to assume that the choke laminate stack should be oriented perpendicular to the OT stack?

SG

[bob p]

yes

[bob p]

when you're done, please let us know if you think it was worth the time, effort and cost.

[bluestom50]

I added a choke supplied by allen amps to my blues junior. I feel that it was worth it , the sound is a little softer,smoother feeling than with the resistor. Also, thanks guys for all you help. Bluestom

[pdf64]

Thanks for the feedback on the mod.
Have you subsequently checked the static dissipation of the EL84 plates, eg with a bias probe?
The lower resistance of a choke (~100 ohms compared to 2k2 of the resistor) will cause the screen grid voltage to rise.
This will make the tube conduct more than before and may result in over dissipation.

Also the value of R24 and R25 may now be too low for reasonable tube life, see JJ_EH_tube_tests
Pete

[Enzo]

Yes, screen voltage rises, and that may be the effect being heard rather than the chokiness. probably 20 volts or so.

[bluestom50]

Here are readings i have gotten---- pin # 2 of both el84 tubes read 12.3 vdc------ ground on + side of main (large} capacitor to brown ot wire reads 4.1 vdc---- r31 and r32 both read12 vdc----- r52 27k resistor read 12.3 on leg near r32 and leg towards 22uf capacitor reads 0 does this mean anything to you guys? As always any help will be appreciated greatly, bluestom

[pdf64]

Sorry it's difficult to understand what measurements you've made from the explanation.
See the schematic link in a previous post here - please can you note your measurements on the rectangular test point boxes, or otherwise note on it which points you are measuring between?
Do you know how to check the static dissipation of the output tubes? Have you got a bias probe?
Pete