Icom: IC-735 no TR no RX any mode

[KD8GWZ]

Hello, new to the site and a relative newbie to Ham Radio in general, but I have a question about an IC 735 I was able to pick up for next to nothing. I was told this radio was used in a mobile CW capacity by one of the previous owners, and the presence of the optional FL-32A filter would seem to suggest that is correct. However, I have not been able to transmit or receive with this radio on any band in any mode.

I am using it on a known good antenna system, and the other radio (I got two of these at the same time) works fine. I have tried just about everything I can think of to try to get this thing working, and have been unsuccessful so far. I have been able to get just a little bit output in CW mode, but so little that it is unintelligible even to stations very close by. Audio output on receive seems abnormally low in all modes except FM and I have yet to receive a single signal even on frequencies known to be in use.

Could the trimmer capacitors in the HPL VCO circuit be the culprit? I have visually inspected every board (front and back) and can see no evidence of any type of failure. Any suggestions would be welcomed. Thanks in advance.--KD8GWZ

 

[iMONITOR]

Considering that radio is about 20 years old, I'd suspect failed capacitors, or bad solder joints. Have you checked for proper voltages?

 

[N1BHH]

Icom 735, hmmm. That's not a scanner! Sure sounds like you have a dead radio. Why not talk to some of the local hams who may have more experience with Icom rigs. It might be time for a new radio.

 

[KD8GWZ]

Well that's about what I figured. I was hoping to find someone here with some personal experience with the 735, but I don't have much in it so I suppose I don't have much to loose.--KD8GWZ

 

[JESSERABBIT]

For what its worth, I have a 735. Had it since new. I fired it up several weeks ago, didn't transmit on it, but receives just fine. I agree, might be the caps, solder joints.

73s de WD4HDC

 

[rescuecomm]

Does this radio have an internal power supply? Since you don't have rx or tx, that is where I would start checking. Sounds like low voltage.

Bob

 

[kh6idf]

I have a 735 also, I'm the original owner. It does not have an internal power supply, it is powered by 12 Volts DC. Right now I'm just using mine as a receiver so I run it off a 12V battery. Mine is still working perfectly. I found a schematic on this web site:

http://www.rigpix.com/schematicsnstuff.htm

It's a downloadable zip file with two jpg files inside.

 

[thams]

OM KD8GWZ,

Did you fix your IC-735 no TR no RX any mode problem? I have an exact problem with my IC-735 that I just picked up recently. Could you please share your experience with me if you did find a solution to your problem. Thanks.

73 de Mike, Va7mt

 

[KD8GWZ]

No I didn't. I have never got it fixed. Not yet anyway. I have been meaning to, but just never boxed it up and sent it out. Good luck with this issue, hopefully you will be more dedicated to fixing the problem than I have been.

73 de KD8GWZ

 

[fineshot1]

I have no affiliation with this fella other than he has done great work for me now & then and is not too expensive and specializes in icom rigs(he was an icom bench tech at one time). Contact him and see
if he can help you - you got nothing to loose.

MTS Ham Radio Repair

 

[thams]

Hi KD8GWZ,

Thanks for the info. I will try to have my rig fixed if I can. I would like to use it for QRP work as I understand that it is a fine rig for that purpose. When I get mine fixed, if it is fixable, I will share with you what the problem is.

Thanks. Mike

 

[gmagyar74]

Icom 735 no TX or RX in any mode

If you look on the back of the radio you will see two RCA jacks, one above the other. There should be a short grey jumper that connects the main radio to the lower printed circuit board, if it is gone, no TX/RX on any mode. Other than that, it could be the VCO trimmer caps. This is a well documented problem with the 735 and can be fixed by replacing the caps with new CERAMIC trimmers. Hope this helps.

 

[N8IAA]

If you look on the back of the radio you will see two RCA jacks, one above the other. There should be a short grey jumper that connects the main radio to the lower printed circuit board, if it is gone, no TX/RX on any mode. Other than that, it could be the VCO trimmer caps. This is a well documented problem with the 735 and can be fixed by replacing the caps with new CERAMIC trimmers. Hope this helps.

I see that you've been a member since 1/13 and this is your first post. However, you woke up a 6 year old thread. I'm sure the original poster has forgotten about this 7 years ago The fact that he hasn't been on since 3/2009.
Larry

 

[KD8GWZ]

Wow, there's a blast from the past! Thank you for your insightful response, however, as some others have suggested this radio is long, long gone. I upgraded to a Yaesu FT-890 and it's been a great little rig.

At any rate, thank you for the reply! I wish I had received it sooner and had been able to keep this radio, but the 890 is a much nicer setup for sure.

 

[K7MEM]

I agree, you should have had the IC-735 fixed. Basic problems are usually caused by not understanding the rig. Plus the stress of operating as a mobile unit could weaken some of the solder joints.

My IC-735 is still in use. I have had to repair it a few time, but it mostly keeps on going. Aside from the usual SSB/CW operation, I use it for digital modes with a home brew Audio/CIV interface. All of the usual digital mode software (FlDigi, HRD, Digipan, Airlink Express, etc. ) works with the IC-735.

Martin - K7MEM

 

[ratboy]

My 735 was a nightmare of bad solder joints,a nd it never saw the inside of a car. It made it just past the point where the warranty expired and then the "fun" began. I opened it up and saw endless bad looking joints. Every six months or so, I would lose transmit power or my audio would go very low. Until the last time it messed up, an hour taking it apart, and hitting any funny looking joints would get it working again. One day, it began blowing fuses on my PS, and I decided I had had enough. I traded it in on a Kenwood TS-450SAT which, except for the very odd AGC, was perfect for the 7 years I had it. There have been great deals offered to me on 735's over the years, and I just pass them up, too many memories.