Yaesu FT-7 not powering on

Discussion in 'Radio Circuits, Repair & Performance' started by GM0MOP, Aug 22, 2019.

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  1. GM0MOP

    GM0MOP Ham Member QRZ Page

    Hi All

    Just got this FT7, but it arrived DEAD. There is a large dent at the back around the earth connection.
    When I connected to my bench PSU 13.6VDC, it does not power on. Dead it looks. I am so disappointed, because I wanted to use it for QRP CW and SSB as well with this classic rig.

    I checked the power cable and fuse, and it is all fine. DC 13.6V is going into the rig OK. Problem is that when power switch is switched on, nothing happens at all.

    What do I have to do to get this repaired? WHere should I look at first?

    Tks & 73

  2. G4COE

    G4COE Ham Member QRZ Page

    Well Jay, you need consider the seller & postal damage before doing anything.... if you planning any of these for recovery you don't want to go messing with it. My first question is was the package damaged? If so I would have considered not accepting it.

    To get things working we need to remove the cover and get access to the DC input socket,
    many of this kind of fault can be cured by simply looking for damaged or broken wires etc. This ought to be your first choice.

    The next thing is to start tracing with a multi meter with power applied checking for 13.8V you may be in luck and may not seem as disastrous as it sounds. All we then need to do is to find where we don't get any 13.8V, a service manual with a circuit diagram would also work wonders, plenty of places where it's freely available on t'internet.

  3. GM0MOP

    GM0MOP Ham Member QRZ Page

    Hello Dave

    Yes, I had talks on this with the seller, and we agreed to settle with partial refunds. I wanted the FT7 from long time ago, so I would wanted some sort of payment adjustment with the seller, and give a go at repairing it, if the deal would be possible.
    And the deal was made. I think it had been clearly damaged by the courier, so the seller will try to claim compensation for the damage.

    Even if the parcel box was not damaged, because it was soft and only single layer of cardboard was just next to the FT7 casing, something dull and hard must have hit it with force, but just managed to damage the hard part of the parcel without puncturing it? That is just my guess.

    But anyway I got it for about 35% of the original price, so I thought I will try to repair it by myself. But right now, I am not sure how this will turn out, because it looks saw tricky and daunting even trying to open the casing and trying to see which wires going where. It is like mixed spaghetti with loads of electrical parts in crammed space. I now realise this this is not same as repairing small AM radio or even restoring valve hifi. HF transceivers are maybe 100s of times more complex, I suddenly realised. :(

    I opened the casing, and was looking for a reverse power blocking diode nearby the DC socket at the back of the FT7, but only thing I can see is a capacitor. From the circuit diagram, there was a diode just next to the capacitor, but in the set, I couldn't locate it.

    I am attaching the photos of the power input socket. Tks & 73 de Jay


    And this is the top of the inside of the FT7.

  4. GM0MOP

    GM0MOP Ham Member QRZ Page

    Screen Shot 2019-08-22 at 22.55.00.png Screen Shot 2019-08-22 at 22.42.43.png Physical damage noticed to the back of the FT7 on arrival. Back panel is dented and earth post twisted.
    Last edited: Aug 22, 2019
  5. WB3BEL

    WB3BEL Ham Member QRZ Page

    There is a lot of black crud on the power connector pins. I wonder why that would be ? Also I guess you took them out of the backshell for some reason or maybe that was part of the shipping damage ? I would look closely at that, and see if they could be cleaned up and reinstalled. Maybe the previous user applied incorrect power ?

    Check the polarity of the power cord. I fixed one of these rigs a long time ago that had the power applied with reverse polarity by the former owner and it destroyed the protection diode and also some internal components. It was a long time ago, but I seem to recall there was a voltage regulator for some of the circuits that had died and some of the filter caps along with it.

    Or maybe there is no continuity through the power pins or the front panel power switch. These are all easy to check with a voltmeter (or ohmmeter with the power off).

    Check that all the plug in modules are seated correctly in their sockets. Maybe something has come dislodged during transit ?

    How much current is this drawing from your power supply ? Nothing ? Or maybe it is current limited ?

    I am guessing that the front panel lights do not light ?
  6. G4COE

    G4COE Ham Member QRZ Page

    I'd be testing for voltage with a multi meter.... luckily there is no circuit boards where that bump occurred, that *may* be a good thing. A dead set of this ilk ought to be easy sort, apply power and then look where there is voltage and no voltage.

    Use a logical approach and you'll get there, assuming and guessing is not the way to go. If I was doing the job I'd be using a test meter with voltage applied.... I do think that is the only way to go.

    I'm not gonna' ask was it working before purchase, a better question might be why was it being sold, that *could* open Pandora's box.

  7. GM0MOP

    GM0MOP Ham Member QRZ Page

    When I opened the FT7, the power connector was in bits. There are tiny plastic strips which are inserted into the back of the power connector in the rig. They were all detached and lying in the rig. They are suppose to embedded in there tightly and form the holes for the power pins, but because they were not there, the power pins were pushed back, and one or two was hanging loose just dangling in space when the back was opened up.

    You can see all the pins in the power socket had been pushed in so much they are almost not there. First time I thought that was just normal. This FT7's power socket pins had nothing to hold them secure, an they were keep going into the rig, and when I opened the rigs 4 of them were just dangling around.
    Screen Shot 2019-08-23 at 14.36.15.png

    But later I found other FT7 on the internet, the power pin sockets are about an inch long.
    Screen Shot 2019-08-23 at 14.35.01.png

    I traced from the positive power in line in the circuit diagram and reached the power on / off switch in the front, and checked the continuity when powered on and off, and it seems OK. Nothing was disconnected or blown, so I connected my bench PSU 13.6V onto the rig, and tapped on the power on button lightly, and it powered on.

    I tried to put all back, but the power connector in the rig was very tricky to reassemble. It took most of the morning and afternoon, to put all back together, and powered on. The FT powered on, but no sound.

    I quickly plugged in my mobile cb speaker at the back of the FT7, EXT SPEAKER jack, and there was sound.

    But no sound from the main speaker under the bottom panel of the rig.

    Power connector has 6x pins, and one of them is connected to the main speaker in the circuit diagram. I checked continuity on that one with DMM, PIN1 and one of the speaker wire to the main speaker, and it was fine.

    But no sound from the main speaker.

    I am not sure if HF band is dead today, but heard absolutely nothing on all bands except a lot of hash noise via my mobile CB speaker connected to back of the FT7.

    But glad that the FT7 is switching on, although no audio from the main speaker.
    I still feel the reassembled power socket in the FT7 is not securely holding the pins, and whenever power plug is inserted not it and taken out, I can see the pins keep going back in. So, potential problem is still there until something more permanent measure can be done to it.

    Tks & 73
    de Jay
  8. G3YRO

    G3YRO Ham Member QRZ Page

    Glad you're getting there Jay . . .

    The FT7 came out shortly after I stopped working for Yaesu, but can see it follows some of their physical and electronic designs of that era.

    Regarding your damaged power socket, I would personally lose it and fit something else (unless you're a purist who wants to keep it totally original). Most small 12V rigs these days just have a flying power lead coming out the back, with an inline connector after a few inches - that would be your easiest/cheapest solution.

    Incidentally, I had to take a Scottish guy to court a couple of years ago to get money back to repair the transit damage on a TS50S I bought from him. I won my case - basically I proved in court that the way he packed it was totally inadequate for a delicate piece of radio equipment, which should have LOADS of soft material between the rig and the box . . . and ideally double boxed.

    (and by the way, no carrier would pay compensation if a delicate item like this was inadequately packed - I had eveidence to that effect I produced in court too)

    Roger G3YRO
  9. G4COE

    G4COE Ham Member QRZ Page

    Yep I'm with Roger... fit a better socket arrangement do make sure it can carry the current the rig needs. The speaker problem should pose no problem, check the speaker itself or the headphone socket/switching arrangement.

    Just in case, keep this link in mind.... HiFi ssb clicking on the logo brand in the middle window. Sort one problem out at a time and you'll get there.

  10. GM0MOP

    GM0MOP Ham Member QRZ Page

    Hi Roger and Dave

    Thank you for your info and advice.

    Yes, I was thinking about replacing the whole power socket to something else, as your suggestion. But was not sure what is available and would work well with the FT7.
    But thank you for your suggestion for the flying power leads for the new rigs. I will have a look at them, and get them for replacement. Thanks.

    No, I am not a purist in rigs at all. I am a pragmatist :) if it works better, that is for me approach :)

    So, I will replace the power socket as your suggestion sooner or later.

    The FT7 is receiving but very tired audio from my old mobile cb speaker connected at the back. Still not sure why the main speaker is not working. I checked the speaker input terminal with my DMM for ohms, and it is not reading anything. Does it mean it is dead?

    And if it is working ok - then what readings should I expect from the 2x speaker wires from the inside of the rig to the speaker on the panel in the rig?

    FT7 is drawing 490mA on receive. It was receiving some CW on 40m the now, but very noisy.

    I do need a dummy load to test the output power as well. I don't have any proper antenna yet, just a piece of wire from the loft for SWLing.

    Trying to get back to HF after a few years of QRT after my father passed away.

    Yes, I think these rigs must be double boxed with plenty of space around it, and stuffed with bubble wraps or strong protective stuff for courier transit for safe arrival.

    Tks & 73
    Jay GM0MOP
    Last edited: Aug 23, 2019

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