Aiwa Volume control

B

BOB URZ

Guest
I had a aiwa cx-na888 come in with a strange volume control
problem. It wants to go to max volume and stay there no matter
which way the shaft is turned. I don't have the manual yet.
Its a rotary encoder, not a liner audio pot. Both sides of the encoder
seem to look the same when turning the control while looking at them
on the scope. Anyone seen this before and have any insight?
I soldered up a few suspicious connections, but no change.

Bob




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I had a aiwa cx-na888 come in with a strange volume control
problem. It wants to go to max volume and stay there no matter
which way the shaft is turned. I don't have the manual yet.
Its a rotary encoder, not a liner audio pot. Both sides of the encoder
seem to look the same when turning the control while looking at them
on the scope. Anyone seen this before and have any insight?
I soldered up a few suspicious connections, but no change.
Click to expand...
I'd guess that the circuit probably runs the quadrature outputs of the
encoder through a circuit to generate either of the following two
sorts of signals:

- separate UP and DOWN pulses, or
- a DIRECTION signal and a CLOCK pulse

and then feeds these into some sort of solid-state potentiometer.

I'd guess that either the quadrature-to-pulse translator is frotzed,
or the solid-state potentiometer chip is bad, or there's a bad trace
between them. The translator might be a separate chip, or might be a
software function implemented in the main microcontroller.

Take a look for a Dallas Semiconductor, Maxim, or Crystal
Semiconductor chip (these are, I think, the commonest solid-state
digital potentiometers) and check out what it expects to see at its
inputs. Work back from there towards the encoder.

--
Dave Platt <dplatt@radagast.org> AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
 
"BOB URZ" <"sound(remove)"@inetnebr.com> wrote in message
news:3FFB4284.2F1F9303@inetnebr.com...
I had a aiwa cx-na888 come in with a strange volume control
problem. It wants to go to max volume and stay there no matter
which way the shaft is turned. I don't have the manual yet.
Its a rotary encoder, not a liner audio pot. Both sides of the encoder
seem to look the same when turning the control while looking at them
on the scope. Anyone seen this before and have any insight?
I soldered up a few suspicious connections, but no change.

I have seen this twice. It was the control itself both times.
Click to expand...
taking it apart and cleaning it will probably fix it, or just get a new one.
You may find turning the knob VERY slowly CCW will reduce the volume;
both I saw acted that way...I think AIWA used too much goo in the
controls...

Viper


Bob




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Click to expand...
 
Bob Urz / Vector Viper:
Yes.... agreed.
Remove the control, disassemble carefully..... clean out most of the goo and
spring out the contact brushes to achieve more tension......... reassemble
and reinstall.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
----------------------------


"Vector Viper" <ahowald@w-link.net> wrote in message
news:vvn0rgrh6qal13@corp.supernews.com...
"BOB URZ" <"sound(remove)"@inetnebr.com> wrote in message

I had a aiwa cx-na888 come in with a strange volume control
problem. It wants to go to max volume and stay there no matter
which way the shaft is turned. I don't have the manual yet.
Its a rotary encoder, not a liner audio pot. Both sides of the encoder
seem to look the same when turning the control while looking at them
on the scope. Anyone seen this before and have any insight?
I soldered up a few suspicious connections, but no change.

I have seen this twice. It was the control itself both times.
taking it apart and cleaning it will probably fix it, or just get a new
one.
You may find turning the knob VERY slowly CCW will reduce the volume;
both I saw acted that way...I think AIWA used too much goo in the
controls...

Viper
Click to expand...
 
Or just order the control - they're only about 3 or 4 bucks. Union
Electronics is a distributor.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Sofie" <sofie@olypen.com> wrote in message
news:vvn4n0io8eupc1@corp.supernews.com...
Bob Urz / Vector Viper:
Yes.... agreed.
Remove the control, disassemble carefully..... clean out most of the goo
and
spring out the contact brushes to achieve more tension.........
reassemble
and reinstall.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
----------------------------


"Vector Viper" <ahowald@w-link.net> wrote in message
news:vvn0rgrh6qal13@corp.supernews.com...

"BOB URZ" <"sound(remove)"@inetnebr.com> wrote in message

I had a aiwa cx-na888 come in with a strange volume control
problem. It wants to go to max volume and stay there no matter
which way the shaft is turned. I don't have the manual yet.
Its a rotary encoder, not a liner audio pot. Both sides of the encoder
seem to look the same when turning the control while looking at them
on the scope. Anyone seen this before and have any insight?
I soldered up a few suspicious connections, but no change.

I have seen this twice. It was the control itself both times.
taking it apart and cleaning it will probably fix it, or just get a new
one.
You may find turning the knob VERY slowly CCW will reduce the volume;
both I saw acted that way...I think AIWA used too much goo in the
controls...

Viper
Click to expand...
 
"Mark D. Zacharias" wrote:

Or just order the control - they're only about 3 or 4 bucks. Union
Electronics is a distributor.

Mark Z.

"Sofie" <sofie@olypen.com> wrote in message
news:vvn4n0io8eupc1@corp.supernews.com...
Bob Urz / Vector Viper:
Yes.... agreed.
Remove the control, disassemble carefully..... clean out most of the goo
and
spring out the contact brushes to achieve more tension.........
reassemble
and reinstall.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
----------------------------


"Vector Viper" <ahowald@w-link.net> wrote in message
news:vvn0rgrh6qal13@corp.supernews.com...

"BOB URZ" <"sound(remove)"@inetnebr.com> wrote in message

I had a aiwa cx-na888 come in with a strange volume control
problem. It wants to go to max volume and stay there no matter
which way the shaft is turned. I don't have the manual yet.
Its a rotary encoder, not a liner audio pot. Both sides of the encoder
seem to look the same when turning the control while looking at them
on the scope. Anyone seen this before and have any insight?
I soldered up a few suspicious connections, but no change.

I have seen this twice. It was the control itself both times.
taking it apart and cleaning it will probably fix it, or just get a new
one.
You may find turning the knob VERY slowly CCW will reduce the volume;
both I saw acted that way...I think AIWA used too much goo in the
controls...

Viper
Click to expand...
I used to get Aiwa though Andrews. It seems lately, they are not answering
my faxes for some reason.

This is a optical type control with a led or such with a photo interrupter,
correct? What's the goo inside doing, blocking one of the Photo
interrupters?

Bob



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Bob Urz:
No.... it is not optical..... it has springy contacts inside that rub
against a rotating disc that generates pulses as you turn the control.......
the thick goo that seems to get thicker with age may impede the proper
contact. Clean out some of the goo (not all of it) and spring out the
contacts to create a firmer tension against the disc.... or order a new
control .... and plan to replace it in a few years.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
-------------------------------


"BOB URZ" <"sound(remove)"@inetnebr.com> wrote in message

This is a optical type control with a led or such with a photo
interrupter,
correct? What's the goo inside doing, blocking one of the Photo
interrupters?

Bob
Click to expand...
 
Bob Urz:
No.... it is not optical..... it has springy contacts inside that rub
against a rotating disc that generates pulses as you turn the control.......
the thick goo that seems to get thicker with age may impede the proper
contact. Clean out some of the goo (not all of it) and spring out the
contacts to create a firmer tension against the disc.... or order a new
control .... and plan to replace it in a few years.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
-------------------------------


"BOB URZ" <"sound(remove)"@inetnebr.com> wrote in message
This is a optical type control with a led or such with a photo
interrupter,
correct? What's the goo inside doing, blocking one of the Photo
interrupters?

Bob
Click to expand...
 
Sofie wrote:

Bob Urz:
No.... it is not optical..... it has springy contacts inside that rub
against a rotating disc that generates pulses as you turn the control.......
the thick goo that seems to get thicker with age may impede the proper
contact. Clean out some of the goo (not all of it) and spring out the
contacts to create a firmer tension against the disc.... or order a new
control .... and plan to replace it in a few years.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
-------------------------------

"BOB URZ" <"sound(remove)"@inetnebr.com> wrote in message

This is a optical type control with a led or such with a photo
interrupter,
correct? What's the goo inside doing, blocking one of the Photo
interrupters?

Bob
Click to expand...
Well, it was as you said. Mechanical encoder. cleaned some of the gunk off,
pulled out the contracts slightly. Put it back together.
Now, it does not want to turn up like it was. So i guess its new
control time or junk time. Well see if Andrews answers my faxes this
time.

Thanks for the help all.

Just for reference, are any of you aiwa warranty?
What kind of support do you get our of Sony for them if
you are?

Bob



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Bob Urz:
Unless you accidentally bent a spring contact or there was an error when you
re-assembled the control or there is a lifted trace on the pcb...... the
repair control should work perfectly..... you may want to double-check
things. ..... or as the reply post by Mark D. Zacharias pointed out, you
could install a new part.
I have fixed dozens and dozens of these controls without a callback or
failure.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -



"BOB URZ" <"sound(remove)"@inetnebr.com> wrote in message
Well, it was as you said. Mechanical encoder. cleaned some of the gunk
off,
pulled out the contracts slightly. Put it back together.
Now, it does not want to turn up like it was. So i guess its new
control time or junk time. Well see if Andrews answers my faxes this
time.

Thanks for the help all.
Click to expand...
 
Sofie wrote:

Bob Urz:
Unless you accidentally bent a spring contact or there was an error when you
re-assembled the control or there is a lifted trace on the pcb...... the
repair control should work perfectly..... you may want to double-check
things. ..... or as the reply post by Mark D. Zacharias pointed out, you
could install a new part.
I have fixed dozens and dozens of these controls without a callback or
failure.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Click to expand...
Strange, after i did it and it was not quite right, i let it sit and cook on the
bench. Tried it latter, and it was much better. If i turned the control slower,
it would work either way. But turing it faster still confused it for some
reason.

Bob




-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----
 
Bob Urz:
It sounds like you may have left too much hardened goo inside? ? ?
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
----------------------------------------


"BOB URZ" <"sound(remove)"@inetnebr.com> wrote in message
news:3FFCBFBC.5D9CD8BA@inetnebr.com...
Strange, after i did it and it was not quite right, i let it sit and cook
on the
bench. Tried it latter, and it was much better. If i turned the control
slower,
it would work either way. But turing it faster still confused it for some
reason.

Bob
Over 100,000 Newsgroups - 19 Different Servers! =-----
Click to expand...
 
Bob Urz:
It sounds like you may have left too much hardened goo inside? ? ?
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
----------------------------------------


"BOB URZ" <"sound(remove)"@inetnebr.com> wrote in message
news:3FFCBFBC.5D9CD8BA@inetnebr.com...
Strange, after i did it and it was not quite right, i let it sit and cook
on the
bench. Tried it latter, and it was much better. If i turned the control
slower,
it would work either way. But turing it faster still confused it for some
reason.

Bob
Click to expand...
 
I had this problem with my pre-amp once. As soon as I turned it on, the
volume would ramp all the way to the top - scared the beejezus outta me!

Once I picked the book up off the remote control on the coffee table, the
problem went away ;-)



"BOB URZ" <"sound(remove)"@inetnebr.com> wrote in message
news:3FFB4284.2F1F9303@inetnebr.com...
I had a aiwa cx-na888 come in with a strange volume control
problem. It wants to go to max volume and stay there no matter
which way the shaft is turned. I don't have the manual yet.
Its a rotary encoder, not a liner audio pot. Both sides of the encoder
seem to look the same when turning the control while looking at them
on the scope. Anyone seen this before and have any insight?
I soldered up a few suspicious connections, but no change.

Bob




-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----
Click to expand...
 
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