All things LA2a related

[Cainester]

Should I put all the tubes in and measure again?

 

[Scenaria]

just dont put the T4b in yet

if you put the tubes in.. go back and check across the neon again.. if everything else looks about right

 

[SSLtech]

yes indeed, the readings are expected to be high without tubes fitted.

I think I typed in some values to check in the notes I sent to Scenaria... They varied by about 5volts or so. When you put the tupes in you should have lower readings on the plate end of the plate resistors. The 6.3V should read about 7-point-something volts off-load also.

The neon should light (takes a long time to decay without warm tubes in!) and should have 55-65 Volts on it.

Keith

 

[Cainester]

ok..
R29 368v
R34 271.1
neon 17.23
heaters 6.8

BTW I had to put a 560pf cap for c13

 

[SSLtech]

that neon... is it lighting up?

 

[Cainester]

negative.

 

[Cainester]

I just gave it some juice from R4 zero adjust and if fired up..

 

[Scenaria]

whats the value across your neon?

 

[Cainester]

17.1 to 52.5 when zero adjust goes from nothing to all.
About mid sweep the voltage goes to 63, but the neon doesn't light. It only lights when the R is about 65%

 

[Scenaria]

set your switch to GR and see if you can dial your VU in at O V.U. with the zero adjust...


might be about time to pop that T4 in there

 

[Cainester]

Yes it will and when it does the voltage across the neon is 52.7 and T4 pin 5 is 8.5

 

[Scenaria]

Rock-N-Roll

your numbers look good

drop that T4 in there :green:

:guinness: :guinness: :guinness: :guinness:

BTW your neon value is a little low.. but so is mine.. still havent figured out why theres such a discrepency from one unit to another...

once the box heats up you will need to readjust the zero setting...

whats your email address?

 

[Cainester]

Scenaria, SSLtech, cayocosta, cjenrick, PRR, and NewYorkDave, you guys ROCK. I have one fully functional LA2a. It is hum free, and is sweet as molasses!! :guinness:.
I will post pictures soon.
Thanks to all
Caine
[cainester @@ aol}

 

[Scenaria]

congrats!

though a little smoke and fire might have been fun :razz:

 

[Cainester]

Ok, I used my LA2 this weekend and WOW! What tone.. What balls.. I only have one problem. It will not limit. If I connect a pot and vary it, there is no differenct in the slope of reduction. I can use a standard 5k lin pot right? I also notice that when I swithc to limit, the resistance at the pot falls to approx 0. Should that happen?

 

[cayocosta]

Waiter - check please.

 

[gyraf]

There is very, very little difference between the comp and limit modes of the LA2A.

Calling it limiting is a huge exaggeration..

Jakob E.

 

[cayocosta]

With R7 at 1k I didn't notice any difference between limit and compress but with R7 at 2.7K it appears to just compress a little more in limit mode.

 

[Cainester]

[quote author="cayocosta"]Waiter - check please.[/quote]
Awww Maaannn :sad:
Ok,
So maybe I didn't think through the 0 ohms too long!
But, I thought the limit was brick wall. If it's not, then it functions correctly.

 

[Cainester]

One last question.....
For today :wink:

The limit / compress switch...
Does closed = compress and open = limit?