Behringer 960M or 980M schematic

[Jazz P Bass]

I am in dire need for above info if anyone can help.
Thanks
JG

[Enzo]

Is that what you are in actual dire need of? Or do you need the power supply or the amplifier? They have been using the HCA2400 power amp on a lot of models lately. And the SMPS is very likely an SPS1000. SO while you may not find those 960 and 980 prints, you might find a PMP5000 or PMP3000 set which I think includes those.

And is that 980M or PMP980M?

[Jazz P Bass]

The mixer is a PMP960M.
I did indeed look at the schematics mentioned.
The SPS1000 uses a TOP221 & a 2153 driver.
The pinouts to the power amp are different.
I have the SPS600 schematic which is also different.
The drivers are discrete.
No, the SMPS on the 960M is new.
There are two separate SMPS on the board.
The + - 15 is derived from the smaller one.
This uses a Fairchield CQ0765RT 5 pin pentawatt IC.
The switching transistor is in the IC.
A KA3525A IC drives it.
The 0765RT was shorted when I got the mixer in.
A scheme would be nice.

[Enzo]

I can't issue the drawing, but I'll try to help if I can. I can identify parts and relationships in there.

The SMPS is a PSU18, seems to be same in PMP980S and PMP960M. Power amp is LPA2400.

The 0765 generates the low voltage rails for the mixer, as I read it. It seems to be pretty self contained, the diodes around it, as in on the primary side, are D16,20,21,26,27 and ZD1, ZD2. The secondary side rectifiers are D10,22,23,24,25. All worth checking

At least Mouser lists the 0765, though out of stock until 12/3. I didn't look elsewhere.

AS I read it, the 3525 is the drive behind the main switcher, not really part of the 0765 circuit.


In fact one small winding off T3, the one the 0765 drives, with D27 and C49 generates the +16v for the 3525 to run on. So if anything, it appears the 3525 is driven by the 0765. Sorta.

[Jazz P Bass]

Quote"In fact one small winding off T3, the one the 0765 drives, with D27 and C49 generates the +16v for the 3525 to run on. So if anything, it appears the 3525 is driven by the 0765. Sorta. "
And it powers the 339 comparator & specifically the 555 timer.
As far as I could trace out the 555 output pin# 3 turns on the main switcher relay & is the shutdown command for the KA3525A controller.
That certainly explains why the main switcher is offline.

[Enzo]

Just in case: There are two 51k in series, R50 and 51, from 120VAC-1 down to pin 3 of the 0765. I assume it is to kick start the thing. If a new one doesnt want to wheel up reliably, check for an open there.

[Jazz P Bass]

Behringer PMP960M.
Can any kind soul clue me in on the power amp connector pinout?

The connector is 8 pins.
One red & 7 black (that's cute!)
As far as I can tell:
pin 1 B+ (red)
pin 2 ?
pin 3 +15V
pin 4 & 5 ground
pin 6 -15V
pin 7 ?
pin 8 B-
Pin 2 & 7 are the ones in question.
Pins 4 & 5 do not appear to be ground for the power rails.

While I am waiting for the parts for the switcher repair, I would like to verify the function of the output section.
There do not appear to be any shorts.

[Enzo]

In cables when there is one color wire and the rest all the same, such as 1 red and 7 black or 1 blue and 5 white, whatever, the odd color indicates pin 1 of the connector.


SOme brands do it different - the colors are all different, but always in color code order, so the red wire would be pin 2, for example. it is all about identifying the connector pin, the schematic calls out the finction of the pins.

In fact look close at the board by the connector. Behr usually silkscreens the function of the pins next to the connector.

1. +80
2. +40
3. +15
4. gnd
5. gnd
6. -15
7. -40
8. -80

[Jazz P Bass]

Thankyou for the info Enzo.
Now, what's with the 80 & 40Vdc.
Are they rail switching ?

[Enzo]

Yes. The SAP16s are your outputs, and the IRFs are commutating the higher voltage rails into the picture as needed.

[Jazz P Bass]

Thanks Enzo.
I have the replacement parts on order for the SMPS.

[Jazz P Bass]

A few questions if you will.
PSU18 SMPS uses a 555 timer. Designated U6.
The trigger pin#2 has a capacitor & resistor tied to PS ground.
C45 & R69 through R46 to V+.
R69 seems to be missing. (knocked off, don't know)
Anyone have the value?
I could also use a verification that U4 comparator pin#12 does indeed go to PS ground.
I am trying to trace this out for reference.

[Enzo]

C45 is called out as a 272
R69 is labeled as NC, so I;d assume not connected, as in omitted in production.

Pin 12 of U4 goes to the same ground as the 555.

[Jazz P Bass]

Thanks Enzo!
O/K.
One last question.
What is the purpose of Q6?
This is why I asked about U4 Pin #12.
The base goes to U4 pin #12.
The emitter is at PS ground.
The collector goes to U8 optocoupler.
Why is the base at PS ground & the emitter.
Makes no sense.

[Enzo]

Base is at ground until the thermal switch opens at 85 degrees C. That would be S2, and C64 in parallel. The switch and cap from base to emitter. When that switch opens, then +16v through 10k R33 pulls up that base, turns on Q6, which grounds its collector. Ground understood not to be earth ground, I know you are aware.

1k R39 in collector lead, and through that Q6 pulls down a control line called PROTE. Protect, I assume. It says "shut down" next to it.

Parallel to Q6 is the transistor half of opto U8a , E to C, and also 47uf C63. The LED half of U8 is turned on by some sort of sense line from the two channels, called DC-OFF.

Ah, PROTE also controls the base of Q7 at your 555.

PROTE is also pulled down by Q8, in a totally different circuit.

PROTE is also connected to the out pin of U4b, pin 1, and U4a, pin 2. U4b appears to be detecting the main side HV, and U4a is detecting VREF

VREF is the supply rail for the 555