MOOG MKPE 3-band parametric equaliser power supply

[pvision]

Looking for a schematic for the power supply in a MOOG Equaliser. There are plenty of schematics for the EQ but I haven't located one for the PSU yet

I am chasing a fault with the PSU. I have recapped it and created a fault then exacerbated it by shorting two pins of the TIP30 whilst probing the PSU

The PSU uses a TIP30 / TIP29 combination with a handful of resistors and a 14-pin DIP chip marked 1468 or 7717. It's not a PSU design I've seen before

Looking for a schematic, an equivalent for the TIP30 and a clue as to what the IC is

Nick Froome

 

[JohnRoberts]

Looking for a schematic for the power supply in a MOOG Equaliser. There are plenty of schematics for the EQ but I haven't located one for the PSU yet

I am chasing a fault with the PSU. I have recapped it and created a fault then exacerbated it by shorting two pins of the TIP30 whilst probing the PSU

The PSU uses a TIP30 / TIP29 combination with a handful of resistors and a 14-pin DIP chip marked 1468 or 7717. It's not a PSU design I've seen before

Looking for a schematic, an equivalent for the TIP30

tip30 probably still available

and a clue as to what the IC is

7717 is probably a date code (year 1977-week 17)

1468 is some kind of hall effect chip so probably not your PS.

good luck

JR

Nick Froome

 

[pvision]

Thanks, John. I'll do my homework and draw out the circuit

Nick Froome

 

[PRR]

If this is +/-15V supply, then it is SG / MC 1468 dual tracking regulator:
https://www.silicon-ark.co.uk/datasheets/mc1468r-datasheet-silicon-general.pdf

Those old dual-reg chips were flaky and could be killed. I would just use any generic +/-15V supply.

 

[JohnRoberts]

If this is +/-15V supply, then it is SG / MC 1468 dual tracking regulator:
https://www.silicon-ark.co.uk/datasheets/mc1468r-datasheet-silicon-general.pdf

Those old dual-reg chips were flaky and could be killed. I would just use any generic +/-15V supply.

Good find, my searches were unsuccessful.

JR

 

[pvision]

Brilliant - thanks chaps.

I have traced enough of the circuit to work out the psu has ± regulated and ± unregulated to the main board. My thought was to dump the existing setup and replace it with a generic supply with regulators, so it looks like its the right approach

I'll draw out the psu anyway in the hope it will help someone else in the future!

Nick Froome

 

[pvision]

An update on the Moog EQ. Connector pinouts. There is a PSU connector that feeds a loom with a multipin that connects to the audio board. It also has a separate two-pin connector for the front panel bypass switch

multipin on board -----------------------------------------power plug
9 - orange - to bypass switch connector
8 - grey - to bypass footswitch socket
7 - blue - blue power --------------------------------------------5
6 - coax - audio OUT
5 - red - red power ----------------------------------------------4
4 - green - to bypass footswitch socket
3 - black - black power -----------------------------------------2
2 - coax - audio IN
1 - green - to bypass switch connector ---------------------3

More updates later

 

[EMUSP1200]

Thanks for the update.  I have one of these that doesn't turn on so your info is helpful.  Please keep us posted.

 

[pvision]

I finally bit the bullet and finished the new psu. The final piece of info I was looking for was found by reading the schematic again. The +23 Volt supply is just rectified DC straight off the bridge, not regulated in any way. Which means that it's a very ordinary ± 15 supply at its heart

I stripped the old transistors & resistors off the psu pcb and left the diodes & caps. I then fitted - with a bit of lead bending and judicious choice of mounting points - a 7815 & 7915  to existing holes & tracks and fitted two jumpers. I didn't cut any tracks

This meant I could retain the pcb and the multipin connection to the loom. Final parts count was two regs. I had already recapped the psu

Critical to getting this right is the correct orientation of the plug that goes on the main pcb. It's not keyed so it is possible to insert it incorrectly. I didn't make the mistake but could see it was possible

There's a non-standard yellow jumper on the main pcb where I have jumpered out the CMOS switch used for the bypass switch

Nick Froome

 

[traucsiliarium]

Many thanks for documenting your process!

 

[axl85]

Hi everyone,
I have a similar unit, Moog mkpe EQ and an issue. Unfortunately the pots which represent “height” for the frequency bands are kind of faulty… Does anyone know where to find pots like that? They are quite special though: stereo, center detent and reverse logarithmic in both directions from the center….
Does anyone have an idea by chance?