The fan in my trusty ICOM 735 has stopped working. This is the small
squirrel cage fan that cools the PA heatsink when the radio is transmitting.
Has anyone ever had a fan failure? The fan itself spins manually. I called
ICOM Canada and they indicated that ICOM no longer stocks parts of this type
for the 15 year old 735. The failure could also be caused by the control
circuit in the ICOM 735 that turns on the fan at different speeds depending
on the temperature of the PA heatsink.

If anyone has a parted out ICOM 735, please let me know. Highly
unlikely --- as ICOM indicated that the ICOM 735 was an extremely reliable
radio.

Any ideas here or experience with this problem? Is there a newsgroup
devoted to ICOM radios?

Regards,
Bernie, VE3FWF, Ottawa, Canada
--

"Bernie Murphy" wrote in message
.. .
The fan in my trusty ICOM 735 has stopped working. This is the small
squirrel cage fan that cools the PA heatsink when the radio is
transmitting.
Has anyone ever had a fan failure? The fan itself spins manually. I
called
ICOM Canada and they indicated that ICOM no longer stocks parts of this
type
for the 15 year old 735. The failure could also be caused by the control
circuit in the ICOM 735 that turns on the fan at different speeds
depending
on the temperature of the PA heatsink.

If anyone has a parted out ICOM 735, please let me know. Highly
unlikely --- as ICOM indicated that the ICOM 735 was an extremely reliable
radio.

Any ideas here or experience with this problem? Is there a newsgroup
devoted to ICOM radios?

Regards,
Bernie, VE3FWF, Ottawa, Canada
--

Try disconnecting the fan and applying appropriate voltage directly to it
w/o the control circuit intervening.
Dale W4OP

I had one of these rigs. I connected the fan directly to 12 volts and
let it run all the time.

Steve

On Wed, 13 Jul 2005 20:30:24 -0400, "Bernie Murphy"
wrote:

The fan in my trusty ICOM 735 has stopped working. This is the small
squirrel cage fan that cools the PA heatsink when the radio is transmitting.
Has anyone ever had a fan failure? The fan itself spins manually. I called
ICOM Canada and they indicated that ICOM no longer stocks parts of this type
for the 15 year old 735. The failure could also be caused by the control
circuit in the ICOM 735 that turns on the fan at different speeds depending
on the temperature of the PA heatsink.

If anyone has a parted out ICOM 735, please let me know. Highly
unlikely --- as ICOM indicated that the ICOM 735 was an extremely reliable
radio.

Any ideas here or experience with this problem? Is there a newsgroup
devoted to ICOM radios?

Regards,
Bernie, VE3FWF, Ottawa, Canada
--

Bernie
There's nothing special about the fan for the 735. They are available
in the Mouser catalog and other parts supply stores. Just measure it
and look. 73 Chris, VE3NGW/W4 Florida

Bernie Murphy wrote:

The fan in my trusty ICOM 735 has stopped working. This is the small
squirrel cage fan that cools the PA heatsink when the radio is transmitting.
Has anyone ever had a fan failure? The fan itself spins manually. I called
ICOM Canada and they indicated that ICOM no longer stocks parts of this type
for the 15 year old 735. The failure could also be caused by the control
circuit in the ICOM 735 that turns on the fan at different speeds depending
on the temperature of the PA heatsink.

If anyone has a parted out ICOM 735, please let me know. Highly
unlikely --- as ICOM indicated that the ICOM 735 was an extremely reliable
radio.

Any ideas here or experience with this problem? Is there a newsgroup
devoted to ICOM radios?

Regards,
Bernie, VE3FWF, Ottawa, Canada

"Chris" wrote in message
...
Bernie
There's nothing special about the fan for the 735. They are available in
the Mouser catalog and other parts supply stores. Just measure it and
look. 73 Chris, VE3NGW/W4 Florida

Bernie Murphy wrote:

The fan in my trusty ICOM 735 has stopped working. This is the small
squirrel cage fan that cools the PA heatsink when the radio is
transmitting. Has anyone ever had a fan failure? The fan itself spins
manually. I called ICOM Canada and they indicated that ICOM no longer
stocks parts of this type for the 15 year old 735. The failure could
also be caused by the control circuit in the ICOM 735 that turns on the
fan at different speeds depending on the temperature of the PA heatsink.

If anyone has a parted out ICOM 735, please let me know. Highly
unlikely --- as ICOM indicated that the ICOM 735 was an extremely reliable
radio.

Any ideas here or experience with this problem? Is there a newsgroup
devoted to ICOM radios?

Regards,
Bernie, VE3FWF, Ottawa, Canada


Have you ever seen the fan in a 735???

I have never seen one like that in a Mouser catalog.
--

Clif Holland, KA5IPF
www.avvid.com

Bernie Murphy wrote:
The fan in my trusty ICOM 735 has stopped working. This is the small
squirrel cage fan that cools the PA heatsink when the radio is transmitting.
Has anyone ever had a fan failure? The fan itself spins manually. I called
ICOM Canada and they indicated that ICOM no longer stocks parts of this type
for the 15 year old 735. The failure could also be caused by the control
circuit in the ICOM 735 that turns on the fan at different speeds depending
on the temperature of the PA heatsink.

I would bet a control circuit failure. Measure the voltage across the fan
and see if there's anything there. I bet there is not.

If the motor has failed, you will probably not see DC continuity across
it either.

While you have it open, put a drop of turbine oil on each of the motor
bearings so they stay good.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Thanks for the posts folks. I had a good look at the schematic and I'll try
various suggestions.
Looks like the fan will run from the 12 volt power rail with a 330 ohm
resistor in series.
The IC-735 has discrete transistors. That should make troubleshooting much
easier
than dealing with surface mount devices.

73, Bernie

"Scott Dorsey" wrote in message
...
Bernie Murphy wrote:
The fan in my trusty ICOM 735 has stopped working. This is the small
squirrel cage fan that cools the PA heatsink when the radio is
transmitting.
Has anyone ever had a fan failure? The fan itself spins manually. I
called
ICOM Canada and they indicated that ICOM no longer stocks parts of this
type
for the 15 year old 735. The failure could also be caused by the control
circuit in the ICOM 735 that turns on the fan at different speeds
depending
on the temperature of the PA heatsink.

I would bet a control circuit failure. Measure the voltage across the fan
and see if there's anything there. I bet there is not.

If the motor has failed, you will probably not see DC continuity across
it either.

While you have it open, put a drop of turbine oil on each of the motor
bearings so they stay good.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."