API 512b Schematic

[OneRoomStudio]

Anyone have the schematic for an API 512b? I would guess the c version would be pretty similar, so that would work too. I have a module here with a burnt resistor (R8), and the schematic I have of a 312 is not of much help. I think the 2520 started to draw current and blew the resistor, but before I go and put another (expensive) opamp in its place, I want to make sure there isn't another underlying problem.

 

[OneRoomStudio]

No one has one?

 

[mitsos]

Or no one is sharing, which sucks, but whatever... 

To get the ball rolling and all, take some macro shots of the thing (front/back) and maybe someone can help you out.

good luck

 

[Biasrocks]

I haven't come across a 512 schemo in all my schematic gathering days, about 10 years worth.

Call API, they should be able to send you one.

Mark

 

[OneRoomStudio]

Thanks guys. I just sent API an email, but I'm not very hopeful. Every time I've asked for a schematic before they've told me that they no longer give out schematics. It's depressing that companies no longer give out schematics for their products. I know they're all paranoid about people stealing their designs, but seriously - why would I want to clone API gear, there are already a million other companies that do that.

I once worked on a PSU for an API 500 series rack (the old linear one, not the switching one). There was an unmarked regulator that had fried, and they wouldn't even tell me what part it was. Why would they need to be protective of that? It's a power supply. Oh well, enough ranting. I'll keep looking around, but if anyone has a schematic handy I would really appreciate it if they could give me a copy.

 

[mitsos]

Well, let us know what happens..

 

[gemini86]

I don't think you can even buy a 2520 from them unless you're sending them the fried one first, they have a huge vendetta against DIYers... (maybe rightfully so, by the looks of how many kits there are, not to mention the 500 series racks becoming popular)

 

[ppa]

I think the companies have fright that a chinese company copies their schematics from diy forums to remake some their products at very cheap price. I remeber you that several european and american companies had problems with cheap clones of their products.

Pier Paolo

 

[CJ]

after Paul Wolfe left, you may as well have thrown a bomb into that place,

 

[jsteiger]

Somebody is just gonna have to reverse engineer a 512c to get the skiz. I would bet my left nut that API will never give one out. Rightfully so I guess...

Someone around must have a working 512c to get you the value of the resistor in question.

 

[mitsos]

I may be able to get access to one at the end of this week, but not sure if the guy'll want me taking the brackets off to get pics of the underside... we'll see...

hey ONEROOM: can you take some macros of yours? That'd probably be easiest since you're gonna do some surgery to it anyway...

 

[helterbelter]

I would bet my left nut that API will never give one out.

Why your left nut ?

Have you lost your right nut with a previous bet ?!? 

just kidding ! 

 

[jsteiger]

Why your left nut ?

Have you lost your right nut with a previous bet ?!? 

just kidding ! 

Ha ha! I can sneak out with the left one every now and again. The wife has the right one in a locked canister on the shelf! Not a "previous bet" but a marriage. I'm not complaining, I don't have a use for those damned things anymore anyhow!  ;D

Seriously though, part of me is a but curious to see a 512 schematic. Besides their current opamps, I would like to know why they sound so edgy/harsh. I seem to remember seeing a pic on an eBay listing and could swear there are 2 IC's on that board. I'm sure one is the meter driver. What the heck is the other one??? Maybe it's a dual IC. I can't recall.

Can someone post a few pics for fun?

Cheers, Jeff

 

[desol]

I don't think you can even buy a 2520 from them unless you're sending them the fried one first, they have a huge vendetta against DIYers... (maybe rightfully so, by the looks of how many kits there are, not to mention the 500 series racks becoming popular)

I bought 4 from them and they never asked for any burnt ones. However, i did tell them it was for my API 312's. Haven't had really any trouble with API per say, although it does seem a little hard to get a phone call or reply back from them. They seem to like to ignore people unless your spending huge dollars.

 

[Biasrocks]

I've got a 512c here that I can liberate,
which resistor is the culprit?

Mark

 

[jsteiger]

I've got a 512c here that I can liberate,
which resistor is the culprit?

Mark

Hey Mark,

What's with the IC's in there? Can you elaborate on those (it)? Is there more than one?

Cheers!
Jeff

 

[Biasrocks]

Hi Jeff,

I think the IC is for the LED Meter iirc.

Got a session this morning, so I'll pull it later today and take some photos.

Mark

 

[jsteiger]

Hi Jeff,

I think the IC is for the LED Meter iirc.

Got a session this morning, so I'll pull it later today and take some photos.

Mark

Hi Mark,

Yes, I assumed it was for the meter. I seem to remember either 2 IC's or a dual or something. I am curious what the other one (if I am not mistaken) is for. 

Thanks, Jeff

 

[OneRoomStudio]

The version I'm working on is the 512b, not the new 512c. I don't know what the differences are, but the 512b only has a single IC, and yes, I'm fairly certain it's the meter driver. The whole circuit is obviously very simple, but there are some differences from the 312 schematic. Aside from phantom power, input transformer, etc, the most obvious difference is the use of the trim pin on the 2520, which isn't even shown on my 312 schematic.

Anyway, if I have time later, I'll try to take some pictures.

 

[OneRoomStudio]

API got back to me - and just as I suspected:

"I am sorry but I can't e-mail you schematic for 512b because it is very similar as current pre-amps (factory policy)."

I might have a chance to take some photo's tonight. The problem is with R8, which is connected to the Trim pin on the 2520.