anyone in NY area have a p2p la2a build?

[sr1200]

The negative poles are facing inward and are connected (front 2 are connected and wired to rear 2... front left positive goes to the top (far side) of R39,  negative goes to star ground.  Front right positive goes to the front (close) side of R39.
The back right positive goes goes all the way over to the front of R9 (3rd front turret) and the left positive connects to R38 which then runs to pin6 of the 6AQ5.

 

[sr1200]

MIGHT have found something big... had an insulated post where i was supposed to have a ground post... crossing fingers.

 

[jwhmca]

AHHHHHH! I was just looking at that going... hmmmmm?

 

[sr1200]

OK ive got gain!!!  ;D ;D ;D ;D
But no gain reduction!  :-[ :-[ :-[

 

[pucho812]

did you pull the t4b?  If so put it back. Gain but no reduction usually means a bad tube also double check voltages now and what do you get?

Lastly looking at the photo I would shrink wrap the leads on the power caps. this is to avoid shorting out, i.e. not accidently touching that bolt and nut holding the small board holding the caps

 

[jwhmca]

you beat me to it!!! Put the T4B back in!

 

[sr1200]

T4 is in, but no reduction even when the knob is fully clockwise.  im now getting about 51 volts across R39!
gonnna take some measurements now, i ordered new tubes today, gain is LOUD and clean, no buz or hum and meter is showing properly in the 2 + modes

 

[jwhmca]

Take the top off the T4B  and shine light on it... see if it works then.

 

[pucho812]

you beat me to that

 

[sr1200]

if i take the sticker off, i void the warranty, i have couple in my La3 that i can take out and test with after i make sure voltages are correct.  Im supposed to measure AC across  somewhere on the T4 to see if its working.  I have a tone gen ready to go.

 

[pucho812]

oh where is the t4b from?

 

[sr1200]

b+ = 362v    @R39 after diodes = 356  @ B+ 304 (still a little high)
  OLD    NEW
V1
1 311  111
2 0  0
3 359  0.96
4 6.4ac  (same)
5 "
6 183  133
7 0    0
8 1.65  1.24
9 6.4ac same

V2
1 359  36
2 341  10
3 359    9.3
4 6.4ac  same
5 "
6 359  215.5
7 322  32.7
8 358  45
9 6.4ac same

V3
1 352  300  ?
2 0  0
3 357    283
4 6.4ac  same
5 "
6 353  299
7 0    0
8 356  282.5
9 6.4ac  same
 
V4
1 233    157.5
2 357    283
3 6.4ac  same
4 "
5 360  300
6 357  290
7 233  159

 

[sr1200]

T4 is a kenetek

 

[pucho812]

cool.  was just curious on the t4b.

O.k. so we found one mistake, with the insulated post maybe post some more pics and we can all take a look. The fact you got nice and clean gain is good.  I have used the la2a as a mic pre from time to time with great results.

 

[sr1200]

Ill take pics of whatever ya want in there! lol cant thank you guys enough!  How do the voltages look?

 

[jwhmca]

The voltages are looking better. Take and post a high rez, well lit shot of the whole thing.

 

[sr1200]

lol as high rez as i can go.  If you want different angles i got the canon loaded

http://www.meirecords.com/images/top.JPG
http://www.meirecords.com/images/board2.JPG

sorry, didn't realize how big that would actually be lol

 

[sr1200]

I just went over the connections again (especially the ground/insulated posts) and everything looks right now.  Im sure blasting 300+ volts across the tubes didn't help.  If i had a tube tester I would check them, but no luck on that.  I have a new set of cheapo tubes coming in on friday or monday.  Hopefully that will solve it.  I'm going to take some final readings tonight with the tubes all out and see what im getting then call it quits...  been losing sleep over this thing. 

 

[pucho812]

loosing sleep? relax it's just diy and just an la2a. it will come together eventually. You know bob moog would say that whenever he ran into a problem he couldn't solve, he would sleep on it and the answer would eventually come, he couldn't explain it other then some higher power would give him the answer through osmosis.

 

[sr1200]

LOL, i wish i knew a quarter of what moog knew.  Yeah, this is my first "fail" project.