That makes sense!! Also, I could easily reproduce the fault by connecting this BUS line to ground!
Quickly, I traced the wire in the service manual, and it appeared to be one of the data lines of the BUS (BPCKA) in the IC-7800. The white flat cable was the problem!Ĭarefully, I removed the ribbon cable and checked it with a microscope (I have an SMD/SMT repair workstation) and noticed the ribbon cable was punctured, probably due to a sharp edge of the sheet-metal resting on the ribbon cable. On this picture you see the power supply with the fan. The screw normally holds the top cover in place. The black screw was replaced to illustrate the location. I was just ready to put the cover back on, when I noticed a ribbon cable running between2 sheets of metal, one of them for supporting the top cover. And there are a lot of connectors! Finally I gave up, and decided to return it to Amcom to see if they can find anything. I took an hour to inspect all connectors and band cables. Alas, it worked as advertised!! Audio from the speakers, and the band switching relays working just fine! This time I powered it up with the top cover removed. I decided to remove the top cover to see if I can find anything loose causing this abnormal behaviour, and moved it (again) to another desk.Īgain tested the rig, to see if moving it solved the problem. We went to do our thing on the 2nd Easter day. I immediately sent an email to Amcom, and explained what happened. 2nd Easter day, in the morning I powered the rig on: no audio, no band relays. Anyway I returned the rig to its normal operation location, and it worked just fine. Power-On and the rig was working just fine! This confirmed what I thought earlier: this MUST be a flat cable sitting loose in its connector. I moved the IC-7800 from its HAM-Shack location to another desk, and connected a power cable. This must be a communication failure between the 'computer' and the 'radio'. So my conclusion was: OK the 'computer' part works fine, the display and all indicators are working, but the 'radio' part is unresponsive. The receivers seemed to receive normally, but were stuck on on a random frequency. The behaviour was as follows: No Audio, no AF gain response, no relays switching the bandpass filters, the Digi-Sel relays which normally rattling while tuning the VFO are unresponsive. I took a closer look to the behaviour, trying to 'reasoning' to the fault. I tried anything: "All clear" reset, re-flash Firmware 2.11 etc. Being more a computer than a radio, this could be something 'software related' and I rebooted the rig. Suddenly the rig did not response to the AF gain knobs. My guess is they encountered the problem described below.Īfter 3 days, I collected my rig, and tested it at home. They had some 'trouble' but I did not ask for specifics. I spoke with Amcom after they completed the update. In my opinion, they did a pretty good job, upgrading this fairly complex and expensive rig. In total there where about 16 minor modifications, and a few more intensive modifications, including replacement of the receivers. I made an appointment with Amcom, our Icom importer here in the Netherlands, and they did the work on all the modifications, prescribed by Icom. 2' with the upgraded roofing filters, and tons of other modifications. Being one of the first IC-7800's from the production line, it needed updating to 'Rev. IC-7800 Flat Cable Fault Icom IC-7800 Flat Cable Fault by Richard Rosenberger PA7FAĪ few months ago, I obtained my dream: an Icom IC-7800 for a reasonable price.
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