Low Phantom power from 500 rack?

[Scodiddly]

Sounds like a bad PSU. Probably you should start worrying that the other outputs are nearing the end of their lives as well.

What do you mean by the other outputs?

Power supply outputs - +48, +15, -15...

[DrummerMan]

Sounds like a bad PSU. Probably you should start worrying that the other outputs are nearing the end of their lives as well.

What do you mean by the other outputs?

Power supply outputs - +48, +15, -15...

Right!

Just checked and they're +16.3 and -16.3

[Scodiddly]

Power supply outputs - +48, +15, -15...

Just checked and they're +16.3 and -16.3

That should be fine. Bipolar aka split rail power supplies go anywhere from +-15 to +-18 in most gear, depending on the design.

As far as power supply wear and age goes, you've got big electrolytic caps gradually drying out, so if one goes then the rest are worth checking or just replacing. If it's a modern switching power supply then there's usually one big cap per section that takes a lot of wear. I've been finding that almost every time I find a dead switching supply it's just a matter of replacing the biggest cap.

[digitaldrummer]

the 10-slot is not a switching PSU.

for the pinout, you might try looking in the bottom right corner- there are some taps there on the board and you could either follow them back to the cable/jack or also check at these taps. Unfortunately I can't read the tiny silkscreen here (photo from the API website). I do see a resistor near one of the connectors. I figured the board in the chassis is a bit more than just traces and connectors.

of course if you know anyone nearby that has the same rack, you could also take your PSU over and try it on theirs to help narrow down if its the PSU or the rack causing the prob.

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[DrummerMan]

Well, API just responded to my email saying they'd be happy to work on it for $120/hr plus parts, or have me contact my dealer to have them deal with it.

That's a bit of a disappointing response. Not entirely sure what my next step is. I'll see if anyone I know has the same unit and can lend me their PS to at see if that's in fact the problem.

[Scodiddly]

You could try measuring resistance between the +48 input pin and the +48 contact on one of the card slots, see if anything is blocking the current. I wouldn't be surprised if there were some low-value (under 1K) resistors to isolate the modules from each other. You could also measure between +48 and ground to see if there's a short.

[The Scum]

Have you peeked in the power supply?

First thing would be to make sure nothing is obviously burned/scorched.

Second thing is to see if there's a fuse on the 48V line, and make sure it's good.

Third thing would be to make sure all components are visibly OK - soldered in place, no legs broken off, etc.

Fourth thing, if nothing obvious falls out of the above, snap a photo and post it here!

48V phantom supplies follow one of a handful of different designs, seeing the components would help identify which strategy they chose (a couple of those strategies can be flaky), and give further ideas for diagnosis.

[digitaldrummer]

more info - again it will help to narrow down to the L200PS or the 500V rack as the problem.
https://www.apiaudio.com/product_specs.php?id=110
https://www.apiaudio.com/docs/brochures/brl200ps.pdf

how long have you had it? API says they have a 5 year warranty
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[DrummerMan]

Have you peeked in the power supply?

First thing would be to make sure nothing is obviously burned/scorched.

Second thing is to see if there's a fuse on the 48V line, and make sure it's good.

Third thing would be to make sure all components are visibly OK - soldered in place, no legs broken off, etc.

Fourth thing, if nothing obvious falls out of the above, snap a photo and post it here!

48V phantom supplies follow one of a handful of different designs, seeing the components would help identify which strategy they chose (a couple of those strategies can be flaky), and give further ideas for diagnosis.

First off, I want to say THANKS for everyone's input here. I know just enough about electronics to get me into trouble and I always feel bad about asking people who've put in the years to handhold me through basic/intermediate shit. Especially considering API aren't being as helpful as one would hope, having all your generosity makes me feel very grateful.


Anyway, I measured phantom at the plug to the chassis and that gave me around 15v. I talked to a local tech who I was recommended to and he said that phantom coming from the power supply would probably be in the mid 60s, then get stepped down to 48 in the chassis (he was talking fast and I don't remember the reason), so that would make sense why it's a little higher at the plug than in the chassis.

Next I opened the unit up. Nothing burned or charred that I can see. There are 2 fuses I can see on the PCB and 2 more fuses right above the MAINS switch on the outside of the unit. I pulled each of the 4 fuses out and checked then all for continuity, and they all seem fine.

There's a handful of what looks like testing points on the PCB where there's a little gold ring sticking up instead of a solder point. One of these is labeled 48v OUT and the other is 48 PRE

Testing 48v OUT gave me the same 15v DC
But testing 48 PRE gave me 67v DC

I'm hoping this means the problem is somewhere between these 2 points. I will have to unscrew the PCB (which will involve unscrewing a handful of other attached components) to see what's between those 2 points.

Any more thoughts before I go down that road?

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[DrummerMan]

more info - again it will help to narrow down to the L200PS or the 500V rack as the problem.
https://www.apiaudio.com/product_specs.php?id=110
https://www.apiaudio.com/docs/brochures/brl200ps.pdf

how long have you had it? API says they have a 5 year warranty
-
api 200ps.jpg

Yeah, unfortunately neither of those gives much more than basic info. I asked them for a schematic and they refused. I've had the unit for 8 or 9 years I think, so out of warranty. And the 5 year warranty is only for parts. I have a feeling they would still charge me that $120/hr unless it was within the 1 year factory warranty.

[DrummerMan]

And a little rant:

I know it's normal to expect companies to not really care about their small time customers, but i guess I've been lucky to deal with enough audio companies that have a pretty generous customer service standard that it pisses me off a bit that API doesn't seem interested enough to make sending a repair to them cost effective.

I've had a couple issues with my AEA stuff over the years, and every time they've just told me to swing by and they've taken care of it super quick with either a minimal or zero charge. Love them.

I had some issues connecting my 10+ year old RME mulitface (which I bought here off of John Davis ages ago) to my new computer, and the U.S. DISTRIBUTOR's ONLY tech support guy worked with me by email and eventually over the phone back and forth for a few days until he worked out the software issue. And this ON A PRODUCT THEY NO LONGER MAKE and for a customer they have no need to support. But they did it anyway. When I AM eventually able to afford a new interface, they've got my business.

Even Electro Voice and Electro Harmonix I contacted recently about repair of some old stuff and they both have minimal bench fees for out of warranty work.

There's definitely something to be said about companies that will still be around in 10 years to be able to fix their stuff, but another level of that is a company that cares whether or not they've satisfied you after the initial purchase.

Anyway, feeling good about the good guys.

/rant

[The Scum]

Testing 48v OUT gave me the same 15v DC
But testing 48 PRE gave me 67v DC

I'm hoping this means the problem is somewhere between these 2 points. I will have to unscrew the PCB (which will involve unscrewing a handful of other attached components) to see what's between those 2 points.

Your gut feeling there agrees with mine.

A couple quick questions:

There are those 3 little black squares that hang of the end of the board - can you transcribe the markings on each of them for us?

In the top picture, center-left, there's a little black cylinder with a silver stripe on the end. Can you read any of it's markings?

And where do each of the wires the leave the frame go? The gray ribbon cable, the 4-conductor (blk/wht/red/red?), and the multicolored (6 conductor?) one?

[The Scum]

In the top picture, center-left, there's a little black cylinder with a silver stripe on the end. Can you read any of it's markings?

Does he say "ZPY33"?

Can you measure voltage across him?

[DrummerMan]

Testing 48v OUT gave me the same 15v DC
But testing 48 PRE gave me 67v DC

I'm hoping this means the problem is somewhere between these 2 points. I will have to unscrew the PCB (which will involve unscrewing a handful of other attached components) to see what's between those 2 points.

Your gut feeling there agrees with mine.

A couple quick questions:

There are those 3 little black squares that hang of the end of the board - can you transcribe the markings on each of them for us?

In the top picture, center-left, there's a little black cylinder with a silver stripe on the end. Can you read any of it's markings?

And where do each of the wires the leave the frame go? The gray ribbon cable, the 4-conductor (blk/wht/red/red?), and the multicolored (6 conductor?) one?

Below are those 3 tabs, from left to right.

When you say the black cylinder, do you mean that large diode? It's labeled D2 on the board and what I can see says BY3 and DC underneath that. There are 3 morde diodes that size throughout the board. On them I can see written Y399, then I see DC underneath. I'm guessing they are all BY399 diodes but can't get a full view of the writing on any of them to be sure.

The Grey ribbon is going to where the 48v switch is, also the LED indicators for 48v, +16v, and -16v are right there as well.

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[DrummerMan]

In the top picture, center-left, there's a little black cylinder with a silver stripe on the end. Can you read any of it's markings?

Does he say "ZPY33"?

Can you measure voltage across him?

I measured all 4 large diodes

D1 and D2 give me 0.018
D3 and D4 give me 0.47