HFU HF Underground
Technical Topics => Equipment => Topic started by: Looking-Glass on February 27, 2016, 0436 UTC
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Came home from work the other day and turned on the FT-1000D Yaesu only to find the receiver totally dead, and I mean dead! Radio transmits OK and everything else works fine except for the receiver, you can VFO from 250KHz to 30MHz and nothing all the way.
I have had this radio since purchased new in 1991 and it has never given an ounce of trouble to me so I guess I can say that I have had a fairly decent run out of it? Done the following so far:
* No burning or burnt smell under the top cover.
* Antenna's are all fine, they work well on the FT-2000D so it's the FT-1000D receiver that has failed.
* Checked for dry joints & loose connections in and around the two SO-239 inlets (the set has the BPF-1 option installed since new).
* Tried swapping antenna access from direct to via the BPF-1 option, nil.
It is so cramped inside that radio I don't want to start taking things apart any more than required, so just a basic spot checking so far. Have downloaded the FT-1000D Service Manual and found it not to be all that helpful, also would need a full bench of test gear, something I do not have.
One option would be to take out the BPF-1 option and see if that may be the problem and if the receiver comes back to life with the BPF-1 removed?
Checked out numerous web sites but have not come across any one with a total receiver failure in an FT-1000D, so can the collective minds here can be pooled with some suggestions? Would be much appreciated. Look-Glass. :'(
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im not sure, but dont the older yaesu transceivers have a small RF "lamp" that is supposed to protect the receiver front end from excessive RF damage ?
its like a small incandescent lamp that will actually light up in the presence of strong RF coming into the radio.
my FT-757GXII has one and it "burnt out" one time with the radio off and caused the exact same problem you are describing.
that could be case with yours, perhaps someone with a very high powered mobile CB radio passed by you in close proximity ?
cant really think of anything else powerful enough to burn out the lamp other than possible voltage on the RF line, excessive static build up or a lightening strike in very close proximity.
a mobile CB radio directly in front of your home would have to operate at 1KW to burn the "lamp" out.
i couldnt locate through google a legit copy of the service manual for this model.
all of the copies i found through google that are "downloadable" are links to malware instead.
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Thanks for the insight, cannot find a inbuilt lamp/fuse that protects the front end, my IC-736 base set had one of those but this radio does not appear to have one either externally or internally. Don't think RF overload was the cause from another radio transmitter as I live in a isolated area with a population of around 200 all on large land tracts. No other radio enthusiasts around here, although there is another radio amateur six kilometers from here but he is not very active.
Lightning strike may be a possibility as I am at 3,654 feet ASL and thunderstorms are regular here, what ever it was happened while the set was off and I was at work. The only antenna that was plugged in was 200 feet of plastic coated wire strung through the trees for my Low Wave DXing on the NavAids NDB band.
The receiver is working, noise comes from the speaker but no signals at all across the bands, will have to investigate the Service Manual a little more when I get the time, it's a huge read and a little all over the place. I managed to download the Service Manual in PDF with no problems from a Yaesu users web site, Fox Tango, I think.
May have another poke around tomorrow and remove the under section, only have the top cover off at present, your input much appreciated... :)
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Trawling through the rather cumbersome FT-1000D Service Manual I found a Lamp Fuse F-9801 on the BPF-1 board option so after a lot of fiddling and jiggling about removed said board and found said F-9801 hidden under a small board mounted on the main, Fuse Lamp looks good, not clouded, and wires inside appear to be fine.
Fired up the radio minus the BPF-1 option receiver board and still the same, dead as from one end of the bands to the other, next step? RX-2 board looks like the next stop but not looking forward in the task of extracting it, wish me luck... :o
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Trawling through the rather cumbersome FT-1000D Service Manual I found a Lamp Fuse F-9801 on the BPF-1 board option so after a lot of fiddling and jiggling about removed said board and found said F-9801 hidden under a small board mounted on the main, Fuse Lamp looks good, not clouded, and wires inside appear to be fine.
Fired up the radio minus the BPF-1 option receiver board and still the same, dead as from one end of the bands to the other, next step? RX-2 board looks like the next stop but not looking forward in the task of extracting it, wish me luck... :o
did you use an ohm meter to check the continuity of the lamp ?
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Spent a little time fiddling with the internals of the FT-1000D, checking for dry joints etc.
Found that I have a rather attenuated receive across most bands when I plug in the wire antenna into the Receive Antenna jack (non SO-239) at the rear of the radio, nothing over strength five but signals! ::)
The Receive Antenna is via a small jack at the rear of the set and utilised by depressing the RX-ANT switch on the front of the radio, this antenna is non transmitting.
Plugging the main antenna back into the SO-239 and removing the wire antenna from the jack returned the set back to totally dead across all bands. Sticking the wire antenna lead into the SO-239 socket produced zero.
So maybe there is a problem with the path between the SO-239 socket and the receiver section, or fizzled component on the RX-2 board itself?
Then again, if the path from the Receiver Antenna jack on the rear was fine I would have big signals and "back to normal" receive function, which I do not have, just weak signals, brings me back to RX-2 board.
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If the receiver has a mechanical transmit/receive relay the contacts may have oxidize or got dirt in them. Sometimes soldering flux from manufacturing will absorb moisture and cause all sorts of problems. Sony had a problem with this in the early 2000's when the world went to water wash flux.
There could be a protection diode in the front end that shorted, or a bad pin switching diode. Sometimes preamps go out too.
The FT857/897 had a problem where the glue/potting material on the IF filters would become conductive and short out the IF path. Check there too.
Without a spectrum analyzer and a signal generator its going to be hard to find. You may be able to extract some 455KHz IF from an AM tuner and inject it into the IF path and see if you can find where it loses the signal.
+-RH
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Thanks RedHat, the radio will have to wait until I get a group of days off from work in two weeks time, have taken your comments and suggestions on board and will be looking at these via the Service Manual...appreciated. ;)