Thank you! I was able to get my ic 725 fixed with these instructions. Mine only had two VCO's with the wrong voltage so it would wander in and out of lock in receive and transmit and the DDS loop needed adjusted. Totally running great now. 73!
Nice job. Good troubleshoot, and good instincts from prior repairs. I got my ham license finally (upgrading to General for HF use next week). You and other RU-vidrs inspired me.
Peter, thanks for a great video on the 726. I have a used 726 that has been working less 6 meters but now all hf received signals go away and then in a while the radio starts working again. My problem I'm fairly certain will be in the VCO. Great systematic troubleshooting video. many thanks Rich KG5IF
Super instruction. Have the same fault on IC728, and it has been stby for 4 yrs now waiting for me to fix it. 2 weeks ago found same fault as you show (but belived it to be the 9 v supply), and then not more time for fixing it.. but now seen your instructions, witch save me a lot of time - and gave me inspiration to get on with the repair. Thanks a lot.. rgds fm oz1fjb - ou2v
Just a note, Peter. Some years ago, I was having similar wiring problems, so, to overcome the short wiring, I made various leads up to plug between these lead to go into the PCB. It was a pain to get the bits together, but they worked fine for many years. If I come across the sealed package (I have moved house 3 times!!) with these connector leads, marked 'Icom extension leads', then I will forward them to you. They look very professional and served me well. 73 de Tony
Very nice repair Peter. I have seen this in various models of radios in the past. Think it may have something to due with age of components. Thanks for sharing
I have one of these oldies, I learned a lot here when looking for issues with spurious carriers generated from within. It didn't help me find them but I sure enjoyed your video with a pint of ale :) 73 G6MMG
Great video, Peter!!! My FT-450AT does the same thing (dropping static) and always thought it was "normal" for some reason! I need to check to see if I get TX or not when it does this. Thank you! 73 de N0BPS
always a perfect job done! I have to say that the layout of these old radios is a bit messy, to many wiring jumps and components are in the lower side of quality in my opininon....
I got my equiptment out and fixed it it was the same adjustment you did I now have full band coverage.the reading was .7 it was to be 1.0 volts this has a trimmer I adjusted it and bam alset thank you
And yet another alternate use for the old tooth brush !! And another real good video !!!! I thought you were going to have a problem with adjusting L 30 with it being held by glue, but you had great success in getting it right !!!!!! I learned a few more tipstoday so many thanks !!! I did not realize that such a minor adjustment could make the difference of bringing the circuit to working , Really valuable knowledge !!!!! and so it was a simple fix --------- John A Bellas KC2UVN
Hi, and thanks for good video. Again. I have just same kind of problem in 726. But only 8-11Mhz was quiet. Both TX and RX. Nasty fault. There was a PWB strip broken. Someone has put too long screw and this was damaged a foil. Just near DDS loop can... It was 8V supply to syntezizer. Other band get power (reduced voltage) by diodes from band swithing lines. Janne OH6LSL
Peter, Nice repair video. If you had a couple cable extensions, would have made positioning the PA unit easier. :-) Noticed the LP-500 was in use. WB3BJU
Thank you Mike! Yes the LP-500 is great. Minor issues on older radios which are not able to let 200Hz passing for the carrier on spectrum mode. In this case you still need your SA for IM3 tests. 73
Very nice Peter. Did you add a bit of paraffin/beeswax to the coil to set it in place again? Or I suppose you should simply use the heat gun to soften/re-harden what's there already. I think Buddy is right, probably just aging components that caused the shift. How about the memory backup battery, was it still good?
Thank you Dino!. There is enough paraffin down on the pcb so I just put my hot solder tip into it and done..Back up is replaced. Buddy is right it is a ageing issue. 73
But... what was broken? Did someone tinker with that subloop inductor? Did other components age, requiring a change in the inductance? I see that there is some potting compound in place, perhaps to stabilize the inductor (physically). Has this deteriorated? Did you replace the potting? I know, 1000 questions! Thanks for considering these.
Hi Mark, the good news is nothing was broken. It was simply a miss-alignment by aged components. The compound you saw is stabilizing paraffin and it is still good.. Hope that anthers everything 73
Hello from UK, 2E0EKU I was wondering if this problem can occur from radio getting dropped at some point in its history as that coil seems very sensitive to adjustment?.
Hi John, well hard to say.. of course a hard hit could potentially do that but I believe those hit must be that strong that the housing would be most probably damaged. In our case the problem is simply caused by ageing... Thanks for watching 73
Brady Handel ; I know your comment is old but just want to warn you don't try to plug it in direct to the wall, you will ruin it. You need a 12 volt DC power supply.
I wonder if replacing that little electrolytic capacitor next to the transistor would have gotten the VCO to an usable range without messing with the coil. That thing could not have moved too much, being covered in wax.
TRX Bench I understand, i have watched the whole video. However it is odd to me how that circuit could have drifted that much by itself since that inductor is fixed with wax. If the aging of that capacitor was the cause then it will keep drifting as time goes on and it will require periodic adjustments, something that should not happen. I have designed and built a FM broadcast band amplifier using 2 transistors and the gain at band ends is adjusted in a similar manner, by adjusting the spacing of an inductor, due to my general dislike of trimmer capacitors. So i totally understand that. But i know and you know too that electrolytic capacitors are among the first components to fail in any electronic circuit. Just throwing that out there. My vintage Philips PM3050 dual 50MHz oscilloscope had some noise on the trace when i got it, even with the input shorted. Replacing the capacitors in the power supply fixed it. Still a good deal for ~70 Euro. I've had it for 5 years i think, and i see it mentioned in the 1989 Philips catalog - that makes it 2 years older than I am! Still a good piece of test gear for what i do (mainly SMPS work), but it does fall a bit short with RF circuits. I am currently watching your review of the miniVNA because i am interested in getting one. Greetings from Romania. Andrei
hi great video. my IC R8500 receiver has issue of no audio. squelch circuit is working fine though.pls do a video or some techniques of troubleshooting this
will wait for that. Also if u can do a proper video on how to properly test vhf Rx and Tx and their detail parameter checks.i need to see such video as part of preventive maintenance. rest u r doing wonderful job m such a huge follower of urs. may GOD bless u for doing such free knowledge spreading for us.
hello , my IC-726 is small power to 6 meter , it is redondante fail ... it is possible research fail to no possible up power all mode ... bad +/- max 2 W fm or +/- 1.5 W SSB ... thank for possible idéa the repair ...
If you see dots in the Display than it is a realy comon fail for this radio. The goop in the VCO stages become conductive. The best and unfortunate the hardest way is to solder out the components and remove the goop complete. After cleaning up replace all components and aligin the VCO ports. 73
I have the IC-729 on 20 meters the receive would cut out but have transmit turn radio off and turn radio back on everything works but now I have lost 8.000mhz to 14.999mhz I have no transmit or receive could this also be the same problem??
Great video Frischdent paid endorsement? LOL Also Peter if you know someone interested in testing antenna modeling software in German Windows version please let me know. Thanks!
