Quad 66 Preamp remote problem

I hope you can help me.

Situation:
I have a Quad 66 Preamp model 2
Quad 66 series 2 SN: Preamp: 210938 (Series 2 Start with SN: 210600)
Processor and Display board is 1 BCP
Processor / Display driver board SN: I34601A

And a Tuner model 66

Issue:
The "Large" remote control no longer works with the preamplifier.
The “Large” remote control does work with the Tuner, search, Track (channels) etc.
It also does not work through the remote wire connection.

The pre-amplifier remains at its last setting, being CD input and at half volume.
The sound is normal/ good.

Now I have schematic for model 1 and not from model 2.

Question:
1_Could anyone help me to get the Model II schematics?

2_I measured some voltages,
IC 10 receives a voltage from pin3 + 7volt and on pin 12 -7volt.
IC 7 8 9 11 12 all have LM339 on pin 3 + 7volt but on pin 12 0volt.
According to the Model I schematics, all these chips should get LM339 +/- 7 volts.
Are these measurements correct, or is there an error in the power supply?

Regulators IC 4 and 5 give normal + and - 8 volts.

Any idea what could be wrong?

Thank you for your time.

Greetings, Joop
 
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Check the RC is good before doing anything. You should 'see' the IR LED light if viewed with a digital camera or webcam.

That doesn't mean the data is correct of course but it is a good start.

You should verify the data is clearly visible on the remote receiver output pin using a scope. It should be clear and defined and probably of approx 5 volt peak to peak amplitude.
 
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Ah, my mistake, I was reading it as 'does not' for some reason.

Hmmm... I'm not really familiar with how the Quad interconnects with regard to R/C commands and so would need to see it all drawn out.

So is there just one single R/C receiver used for all? In other words what R/C options does the preamp have. Is it self contained with a receiver or not.

It's difficult without full service info and diagrams :(
 
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OK, so if each unit is self contained with its own receiver then I think the first step would be to look at the output pin of the receiver in the preamp and see if anything is present when a key is pressed.

Ideally you need a scope to verify this but a meter can be used to get a very inaccurate indication that 'something' is happening by observing a voltage change on the output pin.

As to the voltages... again hard without seeing a correct diagram but I would guess that if a negative rail were missing then there would be other problems beside just an RC issue.

If all these 'pin 12's' have zero volts then a visual inspection of the board should show whether they go to ground or whether they go elsewhere. Worth a measure of them as well to see if they have continuity to ground.
 
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All you can do is keep looking I'm afraid...

Something that might be worth a look. Does the unit have a backup battery or cap. You never know if the logic has got itself in a knot and disconnecting and removing any supply for several hours might be worth a try... assuming it has one rather than using NVM (non volatile memory).

Weird faults like these usually do have a simple cause once you find it.
 
I'm servicing a Quad 66 preamp just this moment :) this is what i found so far:

Check for dry solder joints on the main pcb, almost all dry joints are the via connections on the top side (white side). You'll have to remove the display to see them all.
Replaced 3 blue 100uF caps, 2 on the small RF reciever board & the other (C300) near the regulator IC303. Two had high esr, one was completely open.
Also C306 & C307 (100uF) had high esr so i replaced them too.

The dry joints are preventing the preamp from switching correctly.

Hope this helps....