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Old 5th June 2012, 10:38 PM   #1
Kei is offline Kei  Wales
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Default Leak 2200 maintenance

I've been working on replacing the original electrolytic capacitors and have noticed whilst testing the unit that there is an odd fault.

When switching all the speakers off the right speaker on the A channel still plays. Switch the A channel back on and the left kicks in too. (works as it should) Switch the B channel on only and B plays as it should (no sound from A). Both channels work together too without an issue. Both A & B off and headphones in i get sound out of both channels on the headphones but the right A speaker still outputs.

The right channel on the "DISC" input doesn't work either, but that might be down to a cap or dodgy connection. I'm still waiting on the remainder of the capacitors to arrive.

Does anyone happen to have the service manual for this unit? (My dad supposedly had a paper copy stashed in the attic but cannot find it)

This is the unit in question...
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Last edited by Kei; 6th June 2012 at 11:25 AM.
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Old 6th June 2012, 08:47 AM   #2
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What sort of speaker switch is fitted? Is it that odd metal work gizmo btm. RHS?
I'd check it out while you operate the control and see if any parts are loose or just not making proper contact.
If fitted, slider or rotary switches don' last forever either, so locate the "works" and check that the switch
actions are firm and make positivecontact.
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Old 6th June 2012, 11:36 AM   #3
Kei is offline Kei  Wales
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This is what is shown in the 2100 service manual. (very similar amp, almost the same AFAIK)
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Old 7th June 2012, 11:22 PM   #4
Kei is offline Kei  Wales
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Completed most of the restoration work this evening. Fitted new main filter caps (BHC, 10,000uF 63V) and the rest of the parts replaced with FM/FC. There is a single cap left to replace (behind the volume pot) which should be arriving tomorrow. All of the old caps were measuring a lot higher than their ratings and there has been a fair improvement in sound since changing them. I checked the speaker switch and the wiring and cannot find anything suspect. Gave it a good clean but still no dice.

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Back together.
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Last edited by Kei; 7th June 2012 at 11:31 PM.
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Old 8th June 2012, 01:03 AM   #5
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Looks like a cool amplifier. If it stacks up to the models by Leak before it, Im sure its a quality item, I suspect it was high end in its day.

Does it have a way to play music without the tone controls? What happens with the 4 channel matrix switch?

I wonder if its like I read about in some instructions for a Reel to Reel tape deck and its rectified two channel making a quadraphonic amplifier.

You might have a 4 channel amplifier their, and it might be worth making a simple op amp preamp putting in a 4 channel volume control and ignoring all the rest of the preamp, particularly this crude way of multiplexing quadraphonic signals down two channels, it looks cool

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Old 8th June 2012, 01:12 AM   #6
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Looking closer at your pictures I suspect its only 2 channel?
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Old 8th June 2012, 02:17 AM   #7
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It's quadraphonic, which is analog decoded, 4 from 2 channels, like FM is 2 from 1 channel. The difference is that the licensed trademarks "Quadraphonic" or "SQ4" aren'tused as they belonged to RCA or JVC IIRC. I can't see that there really are an extra 2 channels in these Pics.

The matrix switch will allow different modes of playback in the Phono or Tape modes wich should be bypassed with other inputs like tuner or aux. This was sometimes the only way to avoid those troublesome switches. and the strange sounds that occur when you try Quad playback with a stereo disc. Leave in the off position to avoid problems.

In any event, it's likely the switching of speakers will allow coupling as stereo (parallel pairs) or quad (all separate. These won't be wired in a conventional manner, as you find, so you may have a bit of work ahead sorting the switch wiring out in a manner the suits you. A schematic would help, of course.
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Last edited by Ian Finch; 8th June 2012 at 02:40 AM.
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Old 8th June 2012, 07:24 PM   #8
Kei is offline Kei  Wales
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Fitted the last cap that was missing and had another look at the switches. Gave the wires a "wiggle" and checked to make sure none were possibly making contact with another and couldn't find anything at fault. Put it back together and now the speaker switches work exactly as they should. Seems it just needed a prod.

It was the bottom pair of switches on this board.
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Old 18th June 2012, 05:08 PM   #9
Kei is offline Kei  Wales
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Two more faults i've noticed since putting it back together are that the disc preamp (phono stage) has quite a muffled sound to it and there is some hum that gets amplified. The hum seems to be internal as it doesn't matter how i plug in various devices, its still there. Suggests to me that it is picked up in the preamp, since it increases with volume.
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Old 19th June 2012, 08:35 AM   #10
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At the age of the unit, all electrolytic caps are suspect. At least replace any in the preamp and it should also be configured for stereo, not Quad. mode. I guess you have a conventional MM cartridge of nominal 47k fitted? 'Not sure how these compare to original SQ4 types. It may be worth checking this out.
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Last edited by Ian Finch; 19th June 2012 at 09:04 AM.
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