looking for api 544 input module docs

[Joechris]

Well Jeff, it should be a 1K I belive  . Boji you have forgot the 20k feedback loop before the output cap.. As drawn now you have a open loop,, to much gain!
The input cap is 33mF. Im not going to digg into this myself, Im just waiting for Jeff to get the 8 channel bucket up and running 

 

[jsteiger]

Well Jeff, it should be a 1K I belive  . Boji you have forgot the 20k feedback loop before the output cap.. As drawn now you have a open loop,, to much gain!
The input cap is 33mF. Im not going to digg into this myself, Im just waiting for Jeff to get the 8 channel bucket up and running 

On the original it was 1K. On the Echo modules they use a 20K pan.

...Jeff : I have 2 modules 528, 1 is a vintage ,circa 1972 , and the other is the datatronix era that you've saw in the pictures . The datatronix one has a different 2622 footprint, the room is for a jensen JE 6110K-A PC . And that footprint is the same as the ED's xfmr . Following the tracks it's seems that there's a little mod on them. the way that the pad switch is connected , and there's an R 5 that it isn't on the schematics that us have.( try to find R5 on yours).i will post you a pict tomorrow, now is too late.
regards.
pedro.

Interesting find Pedro. I checked a few of my input modules and no R5 to be found on the PCB's. Are you sure it is something with the input pad?

I did notice that R20 is labeled C20 in the silk.  ;D

 

[PATAPETER]

[/quote]Interesting find Pedro. I checked a few of my input modules and no R5 to be found on the PCB's. Are you sure it is something with the input pad?
Jeff : I don't know what does R5 do .It's placed with R34 and gnd on the other leg....and the pad switch the tracks are different, i'm don't know too much electronics so...i leave it to you....here some pics.

See the bottom switch's tracks...are different .

 

[Tubemooley]

You guys are killing me. I've been doing the same thing over here. I have the 536 schematic from the group e-mail. I've been dissecting that recently. Most of it is pretty straight forward. But following some of the traces is difficult. Now that boji has posted his drawing, that just saved me some time. Shit...... I'm gonna' have to contribute something here soon or I'll just be a scumbag consumer. That ain't no good. DW.

 

[boji]

Hey, the more the merrier. I need more eyes tube, as you can see we have two classes of people here- The have's and the have nots.    :-X

Joechris- Thanks for the cap value. As for the 20k, is not the one to the left of the mic/line switch what you are talking about?

Edit - And yet, the cap comes after the resistor not before, if it matters.

 

[Walrus]

Joechris- Thanks for the cap value. As for the 20k, is not the one to the left of the mic/line switch what you are talking about?

No, there should also be a 20kOhm 1% R and an 82pF 2% cap going from the 2520 output to the 2520 -ve input. The gain setting feedback circuit.

Oh, and C9 is labelled as 220 PICO F on my 548 schematic!! ;D

 

[boji]

Oh SHEESH! yes!  How could I have missed that!    :-\  Thanks.

 

[boji]

Thanks everybody, I understand now where the filters get the signal from, and that can keep me going for awhile, but does DOA #1 only supply the tx?

Tx to EQ, EQ out to S10 pin 13 around to pin 14 to fader in, fader out to pin 15 to filters?

 

[Walrus]

Basically yes.
But it goes via the patch bay so that you can access the Pre-amp out.

 

[boji]

Basically yes.
But it goes via the patch bay so that you can access the Pre-amp out.

Yay. This makes me fuzzy inside. Thanks.

 

[Tubemooley]

boji - Where are you located? DANA.

 

[PATAPETER]

Jeff : What you think about the picts i've posted ?
Pedro.

 

[jsteiger]

Haven't had the extra time to study them closely. Gut tells me I would tend to stick with the early API version. Seems like Datatronix started changing things a little here and there and maybe not always for the best. Think 550a-1. Not a bad eq but definitely not an improved/ better version of the 550a.

 

[PATAPETER]

Jeff:i agree with you. But the change of the mic xfrm to a jensen has something to do with this mods ?Maybe different spects ?
cheers
pedro.

 

[ljfont]

Hey Jeff or Plum, would you mind reposting this document, the link is no longer working, thanks!

Could someone send me the file or link to the 544 docs. Thanks.

ljfont(at)yahoo.com

 

[Tubemooley]

ljfont..... check your e-mail. i will send from tubemooley_at_yahoo.com. DANA.

 

[Polykobol]

Hello,

I missed the schematics and documentation.
Could someone set them back?

Thanks,

PK

 

[jsteiger]

Search the group email account. They are there somewhere.

 

[Polykobol]

HI,

Ok, Jeff, I try to find out. And I should order some knobs.

Pk

 

[Polykobol]

Hi,

Could someone do a scan of the pcb both side?
Would be interesting...

Best regards,

PK