Long time lurker here... I saw a long thread on 4pole switches for usb,
so I thought this may be the place to ask all the knowledgeable
contributors of the newsgroup a question.
I have an old Nakamichi AV-500 that has worked fine for years
(Receiver/Amp with 6 switchable inputs, good solid design with a massive
linear power supply) Yesterday the pushbutton on the front panel which
allows you to bypass tone controls (Bass & Treble) stopped working. It
won't let me use the tone controls. just makes a few clicks when pushed
and seems to be working at a lower than normal volume. So, the amp is
working flat, no tone controls at all. I took it apart (quite a job) and
checked the switch and found an odd situation - as can be seen on the
attachment, I looked over a few normal miniature 4PDT push/latch
switches and the pinout looks very logical (I could only find horizontal
mount, bad switch is vertical mount). This particular switch, although
vertical mount, shows an odd action. almost like one side is reversed.
Hopefully the GIF will explain what I found better than words. Although
I usually have good luck with searches, I can't find anything on this
amp or it's closest model AV-1, and nothing on the ALPS JP 7247 switch.
I don't care if the switch works, I'd rather hardwire it to always use
tone controls, but the pinout doesn't make sense. A schematic would
solve the problem but I have looked for hours with no luck. Anyone ever
see a failure of this type of switch where 2 poles are reversed? I'm
baffled - I've been fixing electronics for 50 years, this one is
confusing.....
Thanks for any assistance-
Rob

On Thu, 20 Sep 2012 00:16:29 -0400, Rob wrote:

Long time lurker here... I saw a long thread on 4pole switches for usb,
so I thought this may be the place to ask all the knowledgeable
contributors of the newsgroup a question.
I have an old Nakamichi AV-500 that has worked fine for years
(Receiver/Amp with 6 switchable inputs, good solid design with a massive
linear power supply) Yesterday the pushbutton on the front panel which
allows you to bypass tone controls (Bass & Treble) stopped working. It
won't let me use the tone controls. just makes a few clicks when pushed
and seems to be working at a lower than normal volume. So, the amp is
working flat, no tone controls at all. I took it apart (quite a job) and
checked the switch and found an odd situation - as can be seen on the
attachment, I looked over a few normal miniature 4PDT push/latch
switches and the pinout looks very logical (I could only find horizontal
mount, bad switch is vertical mount). This particular switch, although
vertical mount, shows an odd action. almost like one side is reversed.
Hopefully the GIF will explain what I found better than words. Although
I usually have good luck with searches, I can't find anything on this
amp or it's closest model AV-1, and nothing on the ALPS JP 7247 switch.
I don't care if the switch works, I'd rather hardwire it to always use
tone controls, but the pinout doesn't make sense. A schematic would
solve the problem but I have looked for hours with no luck. Anyone ever
see a failure of this type of switch where 2 poles are reversed? I'm
baffled - I've been fixing electronics for 50 years, this one is
confusing.....
Thanks for any assistance-
Rob

How did you determine the pin connections with an ohmmeter if the switch
doesn't work? If the ohmmeter test shows that the switch does work, then
the problem lies elsewhere.

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

Jim Mueller wrote:
On Thu, 20 Sep 2012 00:16:29 -0400, Rob wrote:

Long time lurker here... I saw a long thread on 4pole switches for usb,
so I thought this may be the place to ask all the knowledgeable
contributors of the newsgroup a question.
I have an old Nakamichi AV-500 that has worked fine for years
(Receiver/Amp with 6 switchable inputs, good solid design with a massive
linear power supply) Yesterday the pushbutton on the front panel which
allows you to bypass tone controls (Bass& Treble) stopped working. It
won't let me use the tone controls. just makes a few clicks when pushed
and seems to be working at a lower than normal volume. So, the amp is
working flat, no tone controls at all. I took it apart (quite a job) and
checked the switch and found an odd situation - as can be seen on the
attachment, I looked over a few normal miniature 4PDT push/latch
switches and the pinout looks very logical (I could only find horizontal
mount, bad switch is vertical mount). This particular switch, although
vertical mount, shows an odd action. almost like one side is reversed.
Hopefully the GIF will explain what I found better than words. Although
I usually have good luck with searches, I can't find anything on this
amp or it's closest model AV-1, and nothing on the ALPS JP 7247 switch.
I don't care if the switch works, I'd rather hardwire it to always use
tone controls, but the pinout doesn't make sense. A schematic would
solve the problem but I have looked for hours with no luck. Anyone ever
see a failure of this type of switch where 2 poles are reversed? I'm
baffled - I've been fixing electronics for 50 years, this one is
confusing.....
Thanks for any assistance-
Rob

How did you determine the pin connections with an ohmmeter if the switch
doesn't work? If the ohmmeter test shows that the switch does work, then
the problem lies elsewhere.

Looked at all 6 ALPS 4PDT switches; mechanical switching motion is
sideways - parallel to length of switch.
Digikey does not carry ALPS; all slide-type switches found work from
top or side with no spring type return.
Via Mouser, which seems to have a more flexible search scheme, the
best i could find a the NKK MB2181SS4W01-RO and MB2181SD3G01; the C&K
F4UOA TB, the PHA4UEE, the PN41LENA02QE and the PHA4UOA (on first page).
Best way i found was using Electromechanical » Switches, Contact
Form = 4PDT (675 Matches).
Have fun..

On 2012-09-20 06:47, Robert Baer wrote:
How did you determine the pin connections with an ohmmeter if the switch
doesn't work? If the ohmmeter test shows that the switch does work, then
the problem lies elsewhere.


The switch checked out on an ohmmeter but in a very illogical pinout.
What I need to find out is can this switch fail and reverse the
mechanical action of 2 of the 4 poles? What I found (with no
documentation) doesn't help me because I don't know which 2 poles are
correct. So, the switch opens and closes but does it do it correctly...
I assume most of the Nakamichi amps use the same arrangement to bypass
tone control but I can't find any schematics.

Looked at all 6 ALPS 4PDT switches; mechanical switching motion is
sideways - parallel to length of switch.
Digikey does not carry ALPS; all slide-type switches found work from
top or side with no spring type return.
Via Mouser, which seems to have a more flexible search scheme, the
best i could find a the NKK MB2181SS4W01-RO and MB2181SD3G01; the C&K
F4UOA TB, the PHA4UEE, the PN41LENA02QE and the PHA4UOA (on first page).
Best way i found was using Electromechanical » Switches, Contact
Form = 4PDT (675 Matches).
Have fun..
Thanks! It should be loads of fun... I looked over those switches you
mentioned, all are showing the action/pinout one would expect. My switch
is either bad or an oddball with regards to pinout. I'll keep looking
for a schematic.

On 2012-09-20 01:57, Jim Mueller wrote:
How did you determine the pin connections with an ohmmeter if the switch
doesn't work? If the ohmmeter test shows that the switch does work, then
the problem lies elsewhere.

The expected result (from looking at many multiple pole switches) was 4
groups of Form C (SPDT), with the center pin of each group of three
being common and upon actuation, all connections move the same direction
as in a slide switch. I think something mechanical slipped or broke and
is reversing the action of 2 poles. It failed over a week or so, I could
press and latch a few times and it would work, but very scratchy audio.
It's definitely the switch even though it ohms out OK. If I knew which
pair of poles was correct, jumpering it is easy - but no pinouts are
available for this vertical mount in 4 pole, so I don't know which way
is on or off and it's a PITA to disassemble and reassemble to test -
many ribbon cables, screws, pot nuts, knobs, etc. Worse than a laptop!
Closest 2 pole ALPS attached for reference.

Rob wrote:

On 2012-09-20 01:57, Jim Mueller wrote:
How did you determine the pin connections with an ohmmeter if the switch
doesn't work? If the ohmmeter test shows that the switch does work, then
the problem lies elsewhere.

The expected result (from looking at many multiple pole switches) was 4
groups of Form C (SPDT), with the center pin of each group of three
being common and upon actuation, all connections move the same direction
as in a slide switch. I think something mechanical slipped or broke and
is reversing the action of 2 poles. It failed over a week or so, I could
press and latch a few times and it would work, but very scratchy audio.
It's definitely the switch even though it ohms out OK. If I knew which
pair of poles was correct, jumpering it is easy - but no pinouts are
available for this vertical mount in 4 pole, so I don't know which way
is on or off and it's a PITA to disassemble and reassemble to test -
many ribbon cables, screws, pot nuts, knobs, etc. Worse than a laptop!
Closest 2 pole ALPS attached for reference.


Have you tried cleaning it with a good contact cleaner? Not WD40 or
brake cleaner.

On 2012-09-20 15:54, Michael A. Terrell wrote:

Rob wrote:

On 2012-09-20 01:57, Jim Mueller wrote:
How did you determine the pin connections with an ohmmeter if the switch
doesn't work? If the ohmmeter test shows that the switch does work, then
the problem lies elsewhere.

The expected result (from looking at many multiple pole switches) was 4
groups of Form C (SPDT), with the center pin of each group of three
being common and upon actuation, all connections move the same direction
as in a slide switch. I think something mechanical slipped or broke and
is reversing the action of 2 poles. It failed over a week or so, I could
press and latch a few times and it would work, but very scratchy audio.
It's definitely the switch even though it ohms out OK. If I knew which
pair of poles was correct, jumpering it is easy - but no pinouts are
available for this vertical mount in 4 pole, so I don't know which way
is on or off and it's a PITA to disassemble and reassemble to test -
many ribbon cables, screws, pot nuts, knobs, etc. Worse than a laptop!
Closest 2 pole ALPS attached for reference.


Have you tried cleaning it with a good contact cleaner? Not WD40 or
brake cleaner.

That's my next step. I gotta get a can of DeoxIT red. All I have is the
"pens" with felt tips for cables, card edge connectors and such.

Rob wrote:
On 2012-09-20 01:57, Jim Mueller wrote:
How did you determine the pin connections with an ohmmeter if the switch
doesn't work? If the ohmmeter test shows that the switch does work, then
the problem lies elsewhere.

The expected result (from looking at many multiple pole switches) was 4
groups of Form C (SPDT), with the center pin of each group of three
being common and upon actuation, all connections move the same direction
as in a slide switch. I think something mechanical slipped or broke and
is reversing the action of 2 poles. It failed over a week or so, I could
press and latch a few times and it would work, but very scratchy audio.
It's definitely the switch even though it ohms out OK. If I knew which
pair of poles was correct, jumpering it is easy - but no pinouts are
available for this vertical mount in 4 pole, so I don't know which way
is on or off and it's a PITA to disassemble and reassemble to test -
many ribbon cables, screws, pot nuts, knobs, etc. Worse than a laptop!
Closest 2 pole ALPS attached for reference.
If you look at that photo carefully, i would expect that the plunger
moves the sliding switch mechanism, by way of the equivalent of a 45
degree slide motion translator: vertical to horizontal.
Now, presuming that is the case, the 4PDT switch would be exactly the
same, only the horizontal moving bar is larger to accommodate more poles.
That translates to "that switch is moused".
Partial confirmation comes from your observation "It failed over a
week or so, I could press and latch a few times and it would work."

On 2012-09-21 01:46, Robert Baer wrote:
Rob wrote:
On 2012-09-20 01:57, Jim Mueller wrote:
How did you determine the pin connections with an ohmmeter if the switch
doesn't work? If the ohmmeter test shows that the switch does work, then
the problem lies elsewhere.

The expected result (from looking at many multiple pole switches) was 4
groups of Form C (SPDT), with the center pin of each group of three
being common and upon actuation, all connections move the same direction
as in a slide switch. I think something mechanical slipped or broke and
is reversing the action of 2 poles. It failed over a week or so, I could
press and latch a few times and it would work, but very scratchy audio.
It's definitely the switch even though it ohms out OK. If I knew which
pair of poles was correct, jumpering it is easy - but no pinouts are
available for this vertical mount in 4 pole, so I don't know which way
is on or off and it's a PITA to disassemble and reassemble to test -
many ribbon cables, screws, pot nuts, knobs, etc. Worse than a laptop!
Closest 2 pole ALPS attached for reference.
If you look at that photo carefully, i would expect that the plunger
moves the sliding switch mechanism, by way of the equivalent of a 45
degree slide motion translator: vertical to horizontal.
Now, presuming that is the case, the 4PDT switch would be exactly the
same, only the horizontal moving bar is larger to accommodate more poles.
That translates to "that switch is moused".
Partial confirmation comes from your observation "It failed over a
week or so, I could press and latch a few times and it would work."


Robert- you are correct. I found an ALPS switch, vertical mount, 4PDT,
almost the same as original. I'm more interested in the pinout than the
switch as I doubt the switch would physically fit (shaft, pins, etc.).
With this data sheet I now have the switch action which is totally
different than a horizontal mounted one (which works like a slide
switch). The vertical switch when pressed pushes the contacts outward,
when released, they return. See the GIF and attached PDF.
So, now I have the action - I need to remove the old switch and try 4
jumpers in it's place. I also found a schematic on a Nakamichi TA-4
which uses a 4PDT switch in the same "Tone Button" as my receiver,
clearly showing how they bypass the Bass and Treble controls. The part
numbers are different but the circuit is almost the same. Thanks for
your explanation!
Rob

Rob wrote:
On 2012-09-21 01:46, Robert Baer wrote:
Rob wrote:
On 2012-09-20 01:57, Jim Mueller wrote:
How did you determine the pin connections with an ohmmeter if the
switch
doesn't work? If the ohmmeter test shows that the switch does work,
then
the problem lies elsewhere.

The expected result (from looking at many multiple pole switches) was 4
groups of Form C (SPDT), with the center pin of each group of three
being common and upon actuation, all connections move the same direction
as in a slide switch. I think something mechanical slipped or broke and
is reversing the action of 2 poles. It failed over a week or so, I could
press and latch a few times and it would work, but very scratchy audio.
It's definitely the switch even though it ohms out OK. If I knew which
pair of poles was correct, jumpering it is easy - but no pinouts are
available for this vertical mount in 4 pole, so I don't know which way
is on or off and it's a PITA to disassemble and reassemble to test -
many ribbon cables, screws, pot nuts, knobs, etc. Worse than a laptop!
Closest 2 pole ALPS attached for reference.
If you look at that photo carefully, i would expect that the plunger
moves the sliding switch mechanism, by way of the equivalent of a 45
degree slide motion translator: vertical to horizontal.
Now, presuming that is the case, the 4PDT switch would be exactly the
same, only the horizontal moving bar is larger to accommodate more poles.
That translates to "that switch is moused".
Partial confirmation comes from your observation "It failed over a
week or so, I could press and latch a few times and it would work."


Robert- you are correct. I found an ALPS switch, vertical mount, 4PDT,
almost the same as original. I'm more interested in the pinout than the
switch as I doubt the switch would physically fit (shaft, pins, etc.).
With this data sheet I now have the switch action which is totally
different than a horizontal mounted one (which works like a slide
switch). The vertical switch when pressed pushes the contacts outward,
when released, they return. See the GIF and attached PDF.
* I had thought of that possibility, but discounted it due to smaller)
switch actions.

So, now I have the action - I need to remove the old switch and try 4
jumpers in it's place. I also found a schematic on a Nakamichi TA-4
which uses a 4PDT switch in the same "Tone Button" as my receiver,
clearly showing how they bypass the Bass and Treble controls. The part
numbers are different but the circuit is almost the same. Thanks for
your explanation!
Rob

Glad that you have the puzzle resolved; a viable schematic, and found
a (theoretically) replacement switch.