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+--- Thread: FT-847 lost power output on HF (/thread-402.html)
FT-847 lost power output on HF - VK4WDM - 22-09-2017
My FT-847 has lost all power output on HF and 6m.
VHF and HF output OK. No receive problems.Ideas please. I am fearing the worst so I will be sitting down when I read the replies.
73
Wayne VK4WDM
RE: FT-847 lost power output on HF - VK3ALB - 23-09-2017
Hi Wayne,
Download the service manual and work out the HF TX path. Pull the covers off and do some simple troubleshooting - supplies, fuses, plugs, burnt smells, is there RF at the PA input, does the radio switch to transmit, etc
You may be lucky enough to find something that is easy to resolve.
RE: FT-847 lost power output on HF - VK4WDM - 23-09-2017
(23-09-2017, 08:38 AM)VK3ALB Wrote: Hi Wayne,
Download the service manual and work out the HF TX path. Pull the covers off and do some simple troubleshooting - supplies, fuses, plugs, burnt smells, is there RF at the PA input, does the radio switch to transmit, etc
You may be lucky enough to find something that is easy to resolve.
Hi Lou
Yes, will certainly do that but I am kind of hoping that somebody will have experienced this fault before and help narrow the search. I read a statement on another blog that implied that there is a separate internal fuse for the HF PA but I cannot find it on the schematic.
73
Wayne VK4WDM
RE: FT-847 lost power output on HF - VK3HZ - 23-09-2017
The 13.8V supply is common to both PA's - there isn't a separate fuse for the HF/6 PA. So, if 2/70 are OK but not HF/6, it's not the fuse (which is on the AF/Ctl board BTW).
Sorry, no suggestion as to what the fault might be. I've had mine for 15 years without any problems.
Regards,
Dave
VK3HZ
RE: FT-847 lost power output on HF - VK4WDM - 25-09-2017
Problem solved!
The tuner button was stuck in the on position which must have been the result of a knock because I don't have a tuner. It must be faulty because I have to wriggle it to get it to go off and not icon is being displayed. I have bypassed it and will deal with it later.
73
Wayne VK4WDM
RE: FT-847 lost power output on HF - VK3YCQ - 25-09-2017
A suggestion which may help free a stuck button: Disconnect from power and remove potential sources of ignition. Spray in some isopropyl alcohol (Jaycar has it) or methylated spirits. The isopropyl alcohol will leave no residue so you can use quite a bit if needed. Operate the button a few times... if there is built-up grime it may take some time. If there is plaque on the switch contacts it may take 20, 30 or so operations to dislodge it. If you don't have a sprayer, use a cotton bud soaked in alcohol. Don't use WD40 or anything like it. I've used isopropyl on many different controls and switches without ill effects. Of course, if there is major mechanical damage or plaque is too far advanced it won't help, but it's certainly worth a try.
73s
Ian
VK3YCQ
RE: FT-847 lost power output on HF - VK4WDM - 25-09-2017
Hi Ian
Yes, I use a lot of isopropyl alcohol when working on old radios. It can resolve a lot of faults, I call it "resurrection spray."
If I have a stubborn bit of goo I add a very small drop of detergent to about 10mls, put it on with a paint brush, leave it for a few minutes, and then wash it of with more IPA. I will have to work back through the circuit to find out why this switch has such an effect. I thought I had cooked the finals but here was no evidence of that on the PA board.
73
Wayne VK4WDM
RE: FT-847 lost power output on HF - YD5PYS - 06-11-2020
Hello Wayne,
I have almost same problem here, My Yaesu FT-847 lost power on any band SSB Mode , its normal on FM mode ..
Could you guys gimme some clues on what i can do before i do so much damage
I have a video here on facebook Yaesu FT-847 Owners & Support https://www.facebook.com/100000552421549/videos/4006757202685988/
Thank you
73
Dave de YC5YC