Yaesu FT-847Yaesu FT-847The Yaesu FT-847 is a HF/VHF/UHF all-mode transceiver with DSP thatis capable of full-duplex operation for satellite use. I found onefor sale on ebay - not working - it was in a house fire but wasnot the item on fire. The price was commensurate with the challenge and riskI was willing to accept.The previous owner did a fair amount of cleanup on the radio. In fact,it was much cleaner than almost every other radio I've purchased off ebay,but still had some lingering soot issues.RF/BPF board, note the black soot and shredded paper shipping detritusFirst thing I had to do was clean the radio. The front panel, skins,and knobs were all removed and scrubbed with a toothbrush and some'Mr. Clean' spray cleaner and then rinsed with clear water a fewtimes and left to dry.A complete disassembly was necessary to clean the boards. The radioconsists of seven separatecircuit boards interconnected via wire harnesses and coax cables.
New: Added support for the FT-991 and FT-991A. Starting in this release it will no longer be necessary to update to a new firmware with new releases of Win4Yaesu. If you have the base firmware that existed when Win4Yaesu was created it will work even if you do not upgrade firmware versions. Yaesu FT-1D and 'CPU type of the radio is different.' In software ADMS 6 Basically, i connect the radio, turn it on with F, try to clone it with ADMS 6, i get info to press 'band' button and then i get this error: 'CPU type of the radio is different.'
It tookseveral hours to pull each connector and label the connector from which itwas removed. There are 60-70 connectors in total. Once free, each circuitboard was removed from the chassis and static bagged.Partially disassembled, note the blue tape (my favorite!) with thelocation for each connectorThe bare aluminum chassis was also scrubbed with IPA and 'Mr. Clean'.I opted to discard all but the connectors from the cooling fans and purchasenew from DigiKey. The radio may have been ON (and circulating smoke) duringthe incident. I can't tell. The fans weren't worth cleaning.The following are the replacement fans I ordered:small fan:large fan:Both fans exceed the specs (CFM) of the original fan and have lowernoise ratings.
You'll have to solder the connector on these fans, butthey fit exactly.It's almost certain that Yaesu Parts would have had these in stock too.In fact, most of the FT-847 parts (think switches, knobs) I'm seeing onebay are 10x the cost of ordering them directly from Yaesu.After removal, each board was individually sprayed with isopropyl alcohol (IPA) andgently scrubbed with a soft toothbrush several times. When they were'clean' I did a final rinse and dry with more IPA.Reassembly is uninteresting - put everything back where it camefrom. The wire bundles were all separated and each strand cleaned witha paper towel and more IPA. Interestingly the smell from afire was undetectable at this point, significantly different froma cigarette-smoke radio - which is damn near impossible to clean to astate where it doesn't smell. Soot was almost completely removed, there'sstill a little I can't get off the chassis but it's not going to rub offeither, so whatever.The radio didn't power up on first try. I found a tiny void in the traceleading to the front panel switch - not the usual FT847 power switchfailure. I patched that under my 10x stereomicroscope, bridged the switch to stave off future failure and was able tosuccessfully power the radio.Unfortunately the display was garbled.
Poking around with the oscilloscope,there was no data flowing between the head and cpu. The display cpu hadvoltage but not oscillation on the crystal oscillator. A reset didn'tdo anything. The crystal appeared to oscillate at/near the desiredfrequency when tested.what the hell is this?I was able to acquire a new front panel on ebay (minus the display) whichappears to work fine.Now that I can tune the radio.there appears to be no receive on any band.Just static.The Yaesu FT847 service manual is no longer available from Yaesu parts andthe copies on the internet vary from incomplete to unreadable.Fri May 23 22:02:00 CDT 2014Testing what I could, the output from the PLL board was non-existant. ThePLL voltages were basically sawtoothing up back down at a rapid rate.
Again,another PLL board was sourced from ebay. Thankfully, success upon installingthe board. The radio now receives on HF, 2 and 70cm. Just how well is agood question, but I can work on that.Irritatingly, the CW mode doesn't work. When you hit the CW button the radiogoes into transmit which causes my current limited supply to shut down andon and on.Additionally a previous owner modified the radio to transmit everywhere.I changed it back to the factory config.Now that the radio won't TX out of band, I could place the radio out of bandand go into CW mode.
The message 'Error' flickers on the display. It appearsas if the keyer chip (Q1100, a MB8854, one-time mask programmed thing) isstuck in TX.no matter what.
Pin #4 is the output to the radio and theoscilloscope showed a 10kHz (!) square wave there.I desoldered the keyer chip. The radio now goes into CW mode just fineand shorting pin #4 to the CPU causes the radio to TX a tone. I'll probablyreplace this chip with an opto-isolator for the time being.
I see that theYaesu FT-890 and FT-990 both use the same keyer chip, so theoretically Icould repair it. Somehow the CPU also communicates with the keyer chip viathree lines to set it for straight key or iambic mode. I couldn't see anyactivity on those lines so I'm not sure what's going on. If I could, itwould be a relatively simple matter to program a replacement PIC or AVRto handle keying as per the original methods. It will be low on the prioritylist as I'm using an external keyer anyway and really don't want to livewithout the CW memory functions that aren't in this radio anyway.Next up, test the power out, sensitivity and verify alignment.Sun May 25 17:20:25 CDT 2014Not a scientific test, but it's CW WPX weekend. Tuning around with myIC706 the bands are busy.