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Old 24th Aug 2019, 12:56 am   #1
budkor22
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Default Yaesu FT7 speaker no audio

Hi All

Got this FT7, and had problems with no powering. It was bad power socket in the rig. The power socket has 6 pins, 2x for DC power from PSU, 2x for control units (not sure what control units) and 2x for speakers from the circuit diagram from my memory.

After reassembling the power socket, and sat all the pins in it, and then connected power lead, switched on. It came on, but no audio from the speaker underneath the rig which gets connected by 2 wires from the board.

I checked the voltage of the 2x speaker wires, it was 13.5V DC, but there is nothing read on the speaker resistance.

When I disconnect the power plug, and just attach the black and red wires from the bench psu to the pin 2 and 6 on the power socket, which is for - + pins for the powering on, the rig switches on, but no voltage on the speaker wires.

The received audio comes out via external speaker when connected at the back of the rig.

But no sound from the main speaker under the rig, which is attached on the bottom panel.

What is happening here please? Why 13.6 VDC is coming out of the mains speaker wires? Would it be what killed the FT7's speakers? Thanks
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Old 24th Aug 2019, 2:14 am   #2
Terry_VK5TM
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Default Re: Yaesu FT7 speaker no audio

If you have 13.6v across the internal speakers wires, you definitely have something wrong.

As to why you have that on the speaker, look for a wiring mistake somewhere, possibly around the power socket.

Pins 1 & 5 on the power socket have to be strapped together to get the internal speaker working after you have sorted the problem.
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Old 24th Aug 2019, 8:16 pm   #3
G6Tanuki
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Default Re: Yaesu FT7 speaker no audio

Do you get audio if you plug headphones into the "Ear" socket? This will at least tell you if the audio-stages are operating properly.

If you do get audio from the Ear socket, the problem must be in the wiring to the speaker/power plug.
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Old 25th Aug 2019, 10:18 pm   #4
budkor22
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Default Re: Yaesu FT7 speaker no audio

Hi

Yes, the audio comes out via small mobile cb speaker connected at the back of the FT7. It says "EXT SPEAKER".

But the main speaker under the rig is not working at all.

The wire which connects to the main speaker has 13.5 VDC.
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Old 26th Aug 2019, 9:33 am   #5
Jon_G4MDC
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Default Re: Yaesu FT7 speaker no audio

It looks all too easy to connect the speaker to 12V DC by bad wiring of the power plug.

Your speaker has probably been burned out by that.

Better check the wiring of the plug, ensure that 12V on the speaker wires has definitely gone and then fit a new speaker.
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Old 31st Aug 2019, 12:45 am   #6
budkor22
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Default Re: Yaesu FT7 speaker no audio

Yes, the speaker had been burnt. I had to connect another spare speaker.

The speaker problem is now sorted. It turns out that the pins on the input power socket at the back, the some of the wires were bent, and they were shorting each other. I put the torch on, and separated them with flat screw driver, and the 13.5VDC on the speaker wire has disappeared.

And connected a spare speaker I had, into the speaker wire, powered on, and it worked.

But the new spare speaker was too large at the back, and it wouldn't fit into the casing, and I had to connect it from outside of the casing. It looks not neat, but it is working.

I did some tx testing. CW works OK, but ssb tx is problem. When mic keyed up, the output keeps jumping up and down making whining noise from the speaker. It looks like it is outputting some FM or AM modulation with carrier but it cycles on and off while making noise.

And 40m and 80m band output is very low, about half a watt. I tried to tune it with the Tune knob on the front facia of the FT7, but it only peaks another 100mW.
Problem after problem with this FT7.

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Old 31st Aug 2019, 1:20 am   #7
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Default Re: Yaesu FT7 speaker no audio

Remove each plug in card, one at a time, clean edge connector and re insert, check the alignment of the contacts on the main board, the original manufacture had the alignment slightly off.

Low power on some bands can be burnt or faulty output filters most commonly.

Do you have a copy of the service manual?
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Old 31st Aug 2019, 7:49 am   #8
budkor22
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Default Re: Yaesu FT7 speaker no audio

I do have the circuit diagram and original manual for FT7.
Apart from these, is there separate service manual available for FT7?

If the output filters on 40M 80M are burnt, are the parts available? Or is it DIY makable?

Are each modules plug-in type into the board without any screws tightened?

Tks 73
Jay
GM0MOP
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Old 31st Aug 2019, 12:42 pm   #9
G6Tanuki
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Default Re: Yaesu FT7 speaker no audio

Good to hear you found the cause of the speaker problem, if not a 'perfect' solution. Those plastic plugs are not the most-robust of connectors and bent pins are not unknown, specially if you try to fit-them-by-feel as happens in quite a few mobile-installs.

As others have mentioned, check the plug-in-board contacts and reseat.A bit of oxidation on earth- or signal-contacts can cause a myriaid of mysterious and inconsistent effects. Often just a partial lift, a gentle wiggle, and pushing-fully-back-into-the-socket is all that's needed.
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Old 1st Sep 2019, 1:58 am   #10
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Default Re: Yaesu FT7 speaker no audio

There's no seperate service manual for the FT7, all the info is in the one book that came with the rig.

Just thinking about it, another low power problem can be caused by oxidised contacts on the band switch, so another place to check.

Parts, well, unless you are lucky like I was (obtained complete new RF motherboard a few years ago) parts need to come from another donor rig. I had the burnt out filter in the rig I was given and was looking at DIY replacement but didn't get any further in working out what was needed.

The modules are just plug-in, no securing screws.
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Old 1st Sep 2019, 8:54 am   #11
Jon_G4MDC
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Default Re: Yaesu FT7 speaker no audio

Just a silly question but it is good to be sure. This behaviour is being seen into a dummy load - yes?

Just making sure it is not being tested into an antenna and actually RF feedback is to blame.
Very common with SSB!
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Old 1st Sep 2019, 3:52 pm   #12
budkor22
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Default Re: Yaesu FT7 speaker no audio

Yes, it was connected to a 50W dummyload via power and swr meter inbetween. I even checked the dummyload as well. It is made by Zetagi ITALY, and 52 ohms and 50 W rated dummyload.
SWR is 1:1.

I tried CW contact with somebody on 20M, and the antenna is tune for 1:1 SWR. The FT7 is putting out something like constant carrier rather than CW I am sending. No one came back to my call.


I only found it out, when tune my portable SW radio with SSB setting. It sounded like the relay in the FT7 is sticking as well. Constant Dahs? when I am sending callsigns? Never had this experience with any other rigs.
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Old 1st Sep 2019, 3:55 pm   #13
budkor22
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Default Re: Yaesu FT7 speaker no audio

Quote:
Originally Posted by Terry_VK5TM View Post
There's no seperate service manual for the FT7, all the info is in the one book that came with the rig.

Just thinking about it, another low power problem can be caused by oxidised contacts on the band switch, so another place to check.

Parts, well, unless you are lucky like I was (obtained complete new RF motherboard a few years ago) parts need to come from another donor rig. I had the burnt out filter in the rig I was given and was looking at DIY replacement but didn't get any further in working out what was needed.

The modules are just plug-in, no securing screws.
Great info. Thanks.
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