All things LA2a related

[Scenaria]

have you tried a different 6AQ5 tube?

 

[wilebee]

yes a brand new amperex 6AQ5 Wil

 

[cayocosta]

If your mains AC is a little high your heater voltage will be too - no big deal.

Disconnect the grid wire to pin 7 and see if that makes a difference in your plate and screen voltages.

 

[wilebee]

The one that goes to the wiper of r3 I tried that no difference. the problems I was haveing in the prevous posts a few weeks backI found I didnt have the connection from pin7 the the wiper Wil

 

[cayocosta]

Check to see if there is any DC voltage on pin 7.

 

[wilebee]

will do when I'm at home tonight

 

[cayocosta]

Wilebee, I suggest you return to 10k for R34, and 470R for R36. With these in place the voltage should be around 130 plate and 100 screen with about 7 cathode. Give or take 10% or so.

Also, while checking voltage, make sure that you don't have any input signal. Set R3 and R37 to full clockwise (full on). Gain and Peak Reduction to full counter-clockwise (off).

Ron

 

[wilebee]

ok I'l give it a go Wil

 

[wilebee]

ok no dc voltage on pin 7 so I guess i'm chaning out the plate resistor for 10k and the cathode for 470r Wil


Wilebee

 

[wilebee]

ok changed out the 22k plate resistor for 10k and the 1k cathode for 470 and I now have 118 on the plate 113 on the grid and 6.6 on the cathode
thats closer or is that close enough ? Wil

Wilebee

 

[cayocosta]

Wilebee, what's your B+ voltage now?

 

[cayocosta]

The voltages look better now wilebee. The screen grid is still a little high, but maybe you should move on and see how it operates - providing you have everything else sorted out.

 

[wilebee]

ya know i forgot to see what my overall voltage was. I'l check that out and see if i have sparks yet Wil

 

[wilebee]

well its passing a signal but I need to figure out why its not compressing I cant seemt to get the meter to zero out in the GR position Wil

 

[Scenaria]

take the cover off the T4 can and shine some light on the LDRs... does the meter show any deflection in GR mode?

 

[wilebee]

will do tonight

 

[wilebee]

one other odd note I tried the urei t4b I have a and the gain seemed to shoot up but still no deflection on the meter Wil

 

[electronaut]

Scenaria,

Where do you get the housings for your T4s?

Thanks,

E.

 

[CJ]

Housings? We could tell ya, but we would have to kill ya! :razz:
You wouldn't believe what we take out of those things before the T4 stuff goes inside.

 

[Scenaria]

they are NOS octal cans. no way in heck to find em anywhere.. got em from a surplus store (bought the last of them)

wished I knew of a place... but have yet to find any...