Pioneer QX-949A SQ logic

[gitcher]

Hey, I am working on restoring a QX-949A. Mostly working well but not getting one
channel of the SQ logic output. I probed beyound the decoder and all outputs function.
Looks like the M51651P SQ/RM decoder. Can't find any info on this IC. Anyone have a
datasheet or pinout for this unit. I do have the schematic but it doesn't tell all. Any
help appreciated. thanks.
Keith

 

[par4ken]

Hey, I am working on restoring a QX-949A. Mostly working well but not getting one
channel of the SQ logic output. I probed beyound the decoder and all outputs function.
Looks like the M51651P SQ/RM decoder. Can't find any info on this IC. Anyone have a
datasheet or pinout for this unit. I do have the schematic but it doesn't tell all. Any
help appreciated. thanks.
Keith

That "Sub Channel Board" is part of the CD-4 Demodulator, The SQ and RM decoder is a very basic circuit without logic, I see only transistors in that circuit.

 

[gitcher]

That "Sub Channel Board" is part of the CD-4 Demodulator, The SQ and RM decoder is a very basic circuit without logic, I see only transistors in that circuit.

Hi, thanks for the reply. No, the QX949 uses the AWM-048 matrix board which is all discrete transistors. The QX-949A uses the AWM-077 SQ board after the
CD-4 demodulator board. That is where the IC I am looking for is located along with a Sony CX-049 & CX-718D logic and gain chips. I need the M51651P
decorder layout to see if I can sub-in a MC1312P or ECG 799. Sony used a CX-050 in this spot in their designs.

 

[par4ken]

Interesting, I've never heard of that chip before. Looks like it's powered from 30 volts. You could likely use the MC1312P or ECG 799 sub with a bit of surgery and some voltage reduction to supply to chip. I don't think that I've ever seen data on the Sony chips either. I'll keep looking though.

The only other solutions to look out for apart unit or a board from a "parted out" unit.

Edit: Looks like the M51651P can be switched to produce an RM output as well, by blending the front and rear outputs. The RM output is taped off separately and does not use the logic circuit.

 

[gitcher]

Yeah. I have searched everything out there and can't find a match for that chip. It's a Matsushita part though.
Have found a site online that sells a lot of Pioneer parts and he shows the AWM-077 board as in stock. I've left
phone messages and was hoping to hear from, him but nothing so far. He doesn't directly answer any emails
either, just an automated response to call in. I think I will go with the 799 and do the surgery if necessary.
Thanks for the input and looking out for it for me. I'll keep you posted. Keith