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Harman Kardon PM 645



 
 
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  #1 (permalink)  
Old February 24th 07, 03:29 PM posted to uk.rec.audio
Dave Plowman (News)
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Posts: 5,281
Default Harman Kardon PM 645

I've got one of these in for repair (one channel down) and it appears to
be the balance control that's faulty. Cleaning helped in that it now
worked at max (on the faulty channel) but nothing in the middle. Opening
it up revealed a crack in the track.

It's a special in that the first half of the rotation stays at low ohms
while the second goes from that to 50k. The other channel, the mirror of
that. I've come across this before on a Sony amp.

But I can't find a spare. It's an Alps 50KMN (724F) with a centre indent
and the H K number is 5113-50399122.

Anyone know a supplier? I'd guess it's 30 years old.

--
*I'm not as think as you drunk I am.

Dave Plowman London SW
To e-mail, change noise into sound.
  #2 (permalink)  
Old February 24th 07, 03:52 PM posted to uk.rec.audio
Jim Lesurf
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Posts: 3,051
Default Harman Kardon PM 645

In article , Dave Plowman (News)
wrote:
[snip]

It's a special in that the first half of the rotation stays at low ohms
while the second goes from that to 50k. The other channel, the mirror of
that. I've come across this before on a Sony amp.


IIRC that is standard for the 'MN' law of Alps balance pots. They also
usually have a center-detent at the point where both channels have zero
attenuation.

But I can't find a spare. It's an Alps 50KMN (724F) with a centre indent
and the H K number is 5113-50399122.


Anyone know a supplier? I'd guess it's 30 years old.


What physical size/shape is it? I don't recognise the HK number, but I'm
familiar with the Alps pots like this in three versions. The round-case,
the small rectangular box which is better, and the 40mm box which the best
and most expensive.

The last ones I bought like this were from Maplin, but many years ago,
before they became more of a toy and gadget seller than a component seller.
The last Alps 40mm pots I got I blagged out of a commerical factor as
'samples'... :-)

Sorry I can't be more specific, but perhaps a constructional dealer like
Cricklewood can help...

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html
  #3 (permalink)  
Old February 24th 07, 04:28 PM posted to uk.rec.audio
Iain Churches
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Posts: 617
Default Harman Kardon PM 645


"Dave Plowman (News)" wrote in message
...
I've got one of these in for repair (one channel down) and it appears to
be the balance control that's faulty. Cleaning helped in that it now
worked at max (on the faulty channel) but nothing in the middle. Opening
it up revealed a crack in the track.

It's a special in that the first half of the rotation stays at low ohms
while the second goes from that to 50k. The other channel, the mirror of
that. I've come across this before on a Sony amp.

But I can't find a spare. It's an Alps 50KMN (724F) with a centre indent
and the H K number is 5113-50399122.

Anyone know a supplier? I'd guess it's 30 years old.

Dave. The Alps MN series is still available.
One source is:



Iain


  #4 (permalink)  
Old February 24th 07, 05:00 PM posted to uk.rec.audio
Dave Plowman (News)
external usenet poster
 
Posts: 5,281
Default Harman Kardon PM 645

In article ,
Iain Churches wrote:
But I can't find a spare. It's an Alps 50KMN (724F) with a centre
indent and the H K number is 5113-50399122.

Anyone know a supplier? I'd guess it's 30 years old.

Dave. The Alps MN series is still available.
One source is:




Thanks Iain. The pic on their website doesn't look like the version I
have, but I'll try emailing them.

--
*Never kick a cow pat on a hot day *

Dave Plowman
London SW
To e-mail, change noise into sound.
  #5 (permalink)  
Old February 25th 07, 10:24 AM posted to uk.rec.audio
Dave Plowman (News)
external usenet poster
 
Posts: 5,281
Default Harman Kardon PM 645

In article ,
Jim Lesurf wrote:
In article , Dave Plowman (News)
wrote:
[snip]


It's a special in that the first half of the rotation stays at low
ohms while the second goes from that to 50k. The other channel, the
mirror of that. I've come across this before on a Sony amp.


IIRC that is standard for the 'MN' law of Alps balance pots. They also
usually have a center-detent at the point where both channels have zero
attenuation.


Yup. Looking at the Alps site they don't seem to list this sort of thing
these days - I suppose modern stuff uses microprocessor control.

But I can't find a spare. It's an Alps 50KMN (724F) with a centre
indent and the H K number is 5113-50399122.


Anyone know a supplier? I'd guess it's 30 years old.


What physical size/shape is it? I don't recognise the HK number, but I'm
familiar with the Alps pots like this in three versions. The round-case,
the small rectangular box which is better, and the 40mm box which the
best and most expensive.


It's the first version - externally the same as ordinary dual gang ones
available from Maplin, etc.

The last ones I bought like this were from Maplin, but many years ago,
before they became more of a toy and gadget seller than a component
seller. The last Alps 40mm pots I got I blagged out of a commerical
factor as 'samples'... :-)


Sorry I can't be more specific, but perhaps a constructional dealer like
Cricklewood can help...


Not on their website. But I've got a few other leads.

Slainte,


Jim


--
*Santa's helpers are subordinate clauses*

Dave Plowman London SW
To e-mail, change noise into sound.
  #6 (permalink)  
Old February 26th 07, 02:07 PM posted to uk.rec.audio
Dave Plowman (News)
external usenet poster
 
Posts: 5,281
Default Harman Kardon PM 645

In article ,
Iain Churches wrote:
Dave. The Alps MN series is still available.
One source is:




Just had an email back from them saying they only ship within Indonesia.
Weird or what?

--
*Happiness is seeing your mother-in-law on a milk carton

Dave Plowman
London SW
To e-mail, change noise into sound.
  #7 (permalink)  
Old February 26th 07, 04:34 PM posted to uk.rec.audio
Iain Churches
external usenet poster
 
Posts: 617
Default Harman Kardon PM 645


"Dave Plowman (News)" wrote in message
...
In article ,
Iain Churches wrote:
Dave. The Alps MN series is still available.
One source is:




Just had an email back from them saying they only ship within Indonesia.
Weird or what?


Weird indeed. Try a telephone call in your best Urdu or Hindi, or
send a runner with a cleft stick bearing a message in Sanskrit.

I 've bought Alps products from them in the past.
I have several MN pots, but not the one you need.

Iain





 




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