[ICOM] IC-R9000 main vfo encoder repair

[Mike Olbrisch]

Send E-mail to Scott Malcom - mts at toledotel.com  E-mail him with the trouble - he will give suggestions.  But if you need to send it in he does great work too.

BTW - I decided not to fix mine - I sent it to Scott.  Working fine ever since.

Vy73 - Mike - KD9KC.
El Paso, Texas - DM61rt.
W5-SOTA Association Manager.
W5-SOTA info: www.qsl.net/kd9kc/




-----Original Message-----
From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net] On Behalf Of Eric Dobrowansky K2WD
Sent: Wednesday, May 04, 2011 10:31
To: icom at mailman.qth.net
Subject: [ICOM] IC-R9000 main vfo encoder repair




Has anyone rebuilt or repaired the main vfo optical encoder unit for an IC-R9000 receiver? 

I am having an issue with the encoder not funtioning properly. What happens is that the radio only tunes in one direction, and only when the tuning step is selected for above 1KHZ. 

I dissassembled the encoder, and troubleshooted it to component level. If I manually ground (pull low) the sel 0,1,2 lines at the encoder pcb (service manual page 163 for reference), I can make the radio tune properly. However, the encoder leds and opto transistors seem to be the issue.  

The SEL0 transistor and led seen to work fine, thus the reason the 1KHz or higher steps work. But the SEL1 or SEL2 opto diode/transistor pair seem to be malfunctioning. 

I verified that the three infrared LEDs are all emitting fine, but the SEL1 and SEL2 opto transistors seem to not be detecting the light pulses. The collector outputs of both transistors never change state.   The voltages seem to look fine, +5v and ground connections are all good. I thought they may be bad, so I replaced them, and have the same results. I know it is not mechanical, because even if I manually open and close the light path between the diode and transistor, I do not see a change of logic output on my scope for SEL 1 and SEL2, but I can manually cause SEL0 to change state (just like when it is assembled). 

I must be missing something here somewhere. Anyone have any experience with repairing the encoder at this level? 

Thanks 
Eric 
K2CB