Crate PX-600DP Schematic Request

[LarryJ]

I need a schematic for a Crate PX-600DP powered mixer.

I did a dumb thing and took it all apart several months ago and forgot to document the connections between what I believe is the mixer board and the power amp. There are two places on the power amp board for a header connection and I'm not sure which one to use. The original problem was one of the channels, being used for a monitor speaker, would fade out after a few minutes of operation. I took it apart to see if there was anything physical I could see, but got sidetracked and didn't get back to it until recently.

I have a schematic for a PX-700DLX, wondering if there is any similarities between the two devices?

[LarryJ]

bump

[Jazz P Bass]

Can you post the PX-700 schematic?

[LarryJ]

I found it in this forum. Hope this link-back works.

http://music-electronics-forum.com/t17484/

[Jazz P Bass]

So you have one ribbon cable & two connectors?
There should be notations on the circuit board at the connectors.
What are the labels?
How many pins are there?
How many wires are on the cable?
Where does it come from & what is the label on the connector?

[LarryJ]

Jazz,
Sorry for the delay in responding. There are no labels, annotations or designations anywhere on either the circuit board or wire ends. There are 6 red wires terminated with a six position nylon jack that are the ones I can't determine where to reconnect them. This nylon connector jacks into a plug (header) on what seems to be the power amp board. There are two of these 6 position plugs (headers) side by side on the power amp board. The six red wires go from the power amp board to what seems to be the mixer board. There is another connection/wire bundle between the two boards, but that has 4 wires and it is easily determined where that plugs in. I am believing these four wires to be the signal out of the mixer into the power amp.
Power comes out of the transformer to the power amp board. I am making a guess here that the 6 red wires are supplying the power for the mixer PCB. A visual of the traces on the power amp board doesn't give me any clues to which is what. I hesitate to choose one of the headers over the other with the fear that something else may be damaged by an incorrect connection.

Thanks, Larry

[Jazz P Bass]

It would be an odd occurrance for Yamaha to do that to you.
Two headers side by side that have different functions.
Although I could be wrong.
Use your DVM & see if there is any relationship between the two headers.
I am thinking that they are the same.
Measure the resistance from one pin to the same pin on the other header.
If they are connected, then they are duplicate headers.

[LarryJ]

The circuit board traces are not the same. I am believing more and more that the connector is to supply operating power to the mixer PCB from the power amp PCB, as I find no other way for power to get to the mixer PCB. The only other wires between the two PCBs are the four wires; red, green, blue and black wires. My guess is this is the signal from the mixer to the power amp.

I have attached a photo of the headers.

BTW, it's a Crate, not Yamaha.

Larry

[Jazz P Bass]

Sorry for the Yamaha misnomer.
Now Crate I would expect to do something confusing as this.
What I would do is measure the voltage on each header.
Please post the results if you care to do so.

[Enzo]

Looking at the photo, what I see is a 6-pin connector on top, and the one below looks like 12 pins. 6 pins wide, but a double row. Or am I losing it?

[52 Bill]

Enzo I think you lost it a long time ago, I know I did.

The bottom connector has points for 12 pins, but the outer six are not used. The top connector looks like all of the pins are cold soldered and broken loose.

As for how to reconnect the boards, can you trace back any of the lines to/from the preamp connector to an IC? If you can, you can identify which ones are power supply lines and which ones are signal lines.

[hammopter]

I have a PX600DP in for service now. The 6 pin ribbon cable is connected to the set of pins closest to the corner on the PC board.

[LarryJ]

Thank you Hammopter. In the photo I posted above, is that the one on the bottom, the one that the black/red wire is just behind? I'm just not sure if you are referring to the cutout corner or the corner of the board itself.

I did find some bad solder joints on the Amp 2 output jacks, which could have been the original problem. Looking over everything yesterday, there were several other questionable solder joints on both boards. I add this as you may find the same on the one you got in for service.

Larry

[hammopter]

The connector goes on the pins close to the"cutout corner". The problem with this unit was overheating due to fan driver transistor solder joints breaking loose thus disabling the cooling fan.

[LarryJ]

Thanks everyone for the suggestions and help, everything except the fan appears to be working now. I'm getting 24vdc on the connector, but the fan won't turn.

Once again, thanks.

Larry