On 12 Sep 2006 22:46:06 -0700, "Clayton" wrote:

Hi,
I have an Icom IC-290A that I am working on...The problem being that
when I turn the tuning knob it doesn't change frequencies,it acts as if
the knob is slipping.

I had the same problem with an Icom 735. The tuning knob turns an
encoder, which had stopped working. Icom no longer sold the encoder. I
found a repairman who figured out which diodes were burned out, and he
replaced them and got the encoder working again. You might look for a
good repair guy.

Bob
k5qwg


After determining that it wasn't the knob slipping I proceeded to
disassemble the front to get at the tuning potentiometer.
If your familiar with this unit you know that the potentiometer is
continuous and has teeth that catch when you turn the knob to make
tuning easier.
Now when I hook up my ohm meter to the wiper and to either end of the
potentiometer all I get is an OL reading and when I turn the shaft the
reading jumps around wildly. If I connect the meter to the wiper and to
the case of the(I am assuming this is correct?) potentiometer I should
get a reading of Zero ohms but again the only reading I get is OL.

Am I safe in saying that the potentiometer is bad?

If so how do I go about figuring out what type of potentiometer I need
to replace the bad one?
The schematic doesn't tell me what value it is and there isn't a parts
list or part number either.

I hope I have made myself clear enough to be understood,if not please
let me know so I can try and make things clearer.

Any help on this would be greatly appreciated.
Thank you

It's funny that when Clayton turns the encoder quickly there is a frequency
change. I repaired a Kenwood R5000 a few months back that had the same
problem. The cheap plastic disc inside of the encoder was slipping from the
tuning shaft. I was able to super-glue the assembly back together and get it
working again. If it was my own receiver, I would have probably replaced the
encoder with either a Grayhill or Bourns optical encoder.

Pete

"Bob Miller" wrote in message
...
On 12 Sep 2006 22:46:06 -0700, "Clayton" wrote:

Hi,
I have an Icom IC-290A that I am working on...The problem being that
when I turn the tuning knob it doesn't change frequencies,it acts as if
the knob is slipping.

I had the same problem with an Icom 735. The tuning knob turns an
encoder, which had stopped working. Icom no longer sold the encoder. I
found a repairman who figured out which diodes were burned out, and he
replaced them and got the encoder working again. You might look for a
good repair guy.

Bob
k5qwg


After determining that it wasn't the knob slipping I proceeded to
disassemble the front to get at the tuning potentiometer.
If your familiar with this unit you know that the potentiometer is
continuous and has teeth that catch when you turn the knob to make
tuning easier.
Now when I hook up my ohm meter to the wiper and to either end of the
potentiometer all I get is an OL reading and when I turn the shaft the
reading jumps around wildly. If I connect the meter to the wiper and to
the case of the(I am assuming this is correct?) potentiometer I should
get a reading of Zero ohms but again the only reading I get is OL.

Am I safe in saying that the potentiometer is bad?

If so how do I go about figuring out what type of potentiometer I need
to replace the bad one?
The schematic doesn't tell me what value it is and there isn't a parts
list or part number either.

I hope I have made myself clear enough to be understood,if not please
let me know so I can try and make things clearer.

Any help on this would be greatly appreciated.
Thank you

Hi Dale,
Well,unfortunately I don't have a scope(Yet...I know a scope is a must
have when working with this stuff,that's why its at the top of my"Must
Have List")so I am going to take a chance that the encoder is okay once
I reinstall it and test for the 5 volts on the V+ terminal.

Hi Bob,
I wish that were an option,but right not it just isn't going to happen.
This stuff has always been a big interest to me so what better way to
learn.

Hi Pete,
Hey,I better take the encoder back apart(I had it apart once and
cleaned it...there's not much to an encoder is there)I never thought to
check and see if the disk with all the teeth was slipping on the shaft.
I will check that before I put the encoder back in circuit.

You mention replacing yours with a Grayhill or Bourns optical
encoder...If I find that my encoder is the culprit can you just put in
any old encoder? as long as it fits the space and voltage requirements?

Here I go putting the cart in front of the horse again,I better check
the things you all have mentioned first before I do anything else.
I'll let you all know what I come up with.

Thank you everyone.

Hi Clayton,

You should be fine with any Quadrature encoder. 32 pulses per revolution is
about right for the type to order. As long as you have V+ and ground hooked
up properly, it will work. The only mistake that can happen is if Output A
is interchanged with Output B. In that case, the receiver would tune
backwards.

Pete

"Clayton" wrote in message
oups.com...

Hi Dale,
Well,unfortunately I don't have a scope(Yet...I know a scope is a must
have when working with this stuff,that's why its at the top of my"Must
Have List")so I am going to take a chance that the encoder is okay once
I reinstall it and test for the 5 volts on the V+ terminal.

Hi Bob,
I wish that were an option,but right not it just isn't going to happen.
This stuff has always been a big interest to me so what better way to
learn.

Hi Pete,
Hey,I better take the encoder back apart(I had it apart once and
cleaned it...there's not much to an encoder is there)I never thought to
check and see if the disk with all the teeth was slipping on the shaft.
I will check that before I put the encoder back in circuit.

You mention replacing yours with a Grayhill or Bourns optical
encoder...If I find that my encoder is the culprit can you just put in
any old encoder? as long as it fits the space and voltage requirements?

Here I go putting the cart in front of the horse again,I better check
the things you all have mentioned first before I do anything else.
I'll let you all know what I come up with.

Thank you everyone.