Roll Call: Who's building, built, or thinking of building a beta22?

[el_matt0]

as predicted, here we go as i begin to run into a massive SLEW of problems with my b22/s22 must undoubtedly at least partially due to my inexperience. instead of the "i told you so's" that im SURE are justified, im wondering if anyone can try to help to get me out of this hole that im in. relating to just my s22, ive got it wired with IEC, fuse, switch etc, and ive got my transfo wired up too. just went to do the initial power on checks and voila, nothing at all. absolutely squat, the fuse still isnt blown and ive checked that the cord is good so...obviously i went awry somewhere! ive inspected my board and all the joints look quite good, there are no obvious short circuits or solder bridges. im just seeing no signs of life once i turn it on plugged in (and when the switch is "off" for that matter so its not like i rigged it up backwards!!). also, i tried measuring DCV between the G and V+ of the output terminal block, and there is no visible readings at any point. im going to post up a few cell phone pics in a minute, this is very disheartening, as obviously this is NOT a good start

! PLEASE let me know if you have any suggestions at ALL.

 

[n_maher]

It will be impossible to help without pictures. Take high-res, in focus pictures of the top and the bottom of the board with it wired as you currently have it, cell phone pictures probably aren't going to help at all.

If you're getting nothing and the fuse isn't blown I'm betting you've got the trafo wired wrong so I'd check that again, even if you think you've got it right. If pictures prove impossible try and described how you have it wired. Tell us what trafo it is (make, model) and what color wires you have connected to what.

 

[el_matt0]

just realized i cant post pics cuz i dont have hosting, i can email anyone that has the heart to offer me personal help

! for references sake, i am using the identical transformer to fierce_freak, and i have it wired identically to as can be seen in his pic below.
http://www.lightmedark.com/p/mod/b22f.jpg
i might not be using the exact same IEC and switch as him, but that really shouldnt make a difference like this obviously i assume?

 

[n_maher]

PM me your email address, I'll host them.

 

[el_matt0]

additional info. its an AvelLindberg Y236405. looking at the IEC from the back (like in fierce's pic above), i have the purple and blue wires twisted as a pair and soldered to the "top right" lug on the IEC (from the back view). the "top left" lug on the IEC is wired with 18 AWG to the top lug on my switch, the bottom lug of the switch being soldered to the twisted pair of grey/dark brown wires from my trafo. the 3rd "bottom right" lug on the IEC is simply wired to the chassis. in terms of secondaries, as seen in fierces above, my order from left to right (with the terminal block on the FAR side of the board from you) is yellow, orange, red, black.

 

[el_matt0]

incase the text description doesnt cut it for you guys

nate has been generous enough to offer to host a few pics for me so those will be up in the next hour or so hopefully, just gotta find a camera

 

[n_maher]

I don't think you've got the trafo wired correctly, try (from L to R) red, black, orange, yellow. See picture below.

[edit]I just reread your description, you've definitely got red and black flipped, switch those two and see what happens.

 

[mb3k]

Cool, matt, I'll take a second look at it also. I'm in the process of the ground channel, hopefully I can finish all the channels in a week or two.

I'm in a small dilemma here. For the transistor matching - particularly the output mosfets:
Q21, Q22 - match these for Vgs within 0.3V
Q23, Q24 - match these for Vgs within 0.3V
This question is aimed toward AMB... With the tested complementary pair IRFZ24N / IRF9Z34N, what do you specifically test for? I would assume no matching is done with those?

 

[el_matt0]

@ nate, THATS what jeff rossel said tOO! however, i was using fierce_freaks as a guide, and looking from him, the order is yellow orange red black i think!!! i sent jeff rossel back an email asking to clarify, and ti kan replied saying that fierce's order is correct.....so.....WHAT is the correct order??? heres his email sent last night:
"It should be yellow-orange-red-black (either left to right or right to left,
it doesn't matter).

-Ti"

soooooooooo........should i try the swap or no

 

[vvs_75]

correct:from L to R: yellow, orange, red, black

 

[el_matt0]

k so i wont try swapping them then?, and...still lifeless

 

[n_maher]

Matt,

I'm downloading your pictures now and I'll try to get them up as soon as I can. Bottom line, I don't think that either configuration is wrong, one may result in the two secondaries being out of phase with each other but as long as black and red are used as a pair and correspondingly yellow and orange the PS should work fine.

As a check take the wires out of the sigma22, apply power to the trafo and check the output across one of the pairs (black/red for example). You should read about 30VAC, probably a bit higher. Make sure that the other leads are kept separate, you don't want to short part of the trafo. Clearly if you don't get the right measurement here something upstream is wrong (IEC wiring, for example).

 

[n_maher]

 

[thrice]

Check to see if your transfo is wired right...you'll want to remove it and test it as n-Maher mentioned.

If that's all good then you may need to check operating voltages on the board when powered up. AMB has schematics detailing the operating voltages:

+/- 30V http://www.amb.org/audio/sigma22/s22_30v_voltages.pdf

+/- 24V http://www.amb.org/audio/sigma22/s22_24v_voltages.pdf

+/- 15V http://www.amb.org/audio/sigma22/s22_15v_voltages.pdf

Probably some transistor somewhere is shot. Check Q1 and Q2 first and work your through the schematic.

Oh yeah, don't shock yourself

 

[thrice]

On second glance...are your diodes on correctly...perhaps it's just the light playing tricks,but they may be reversed.