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Old 6th Oct 2018, 11:24 am   #21
Phil G4SPZ
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Default Re: Yaesu FT290R Mk 1 squelch fault

Good idea Sparky, I'll try that. Thank you.
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Old 6th Oct 2018, 11:53 pm   #22
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Default Re: Yaesu FT290R Mk 1 squelch fault

I'm delighted to be able to report a happy ending to this saga! The radio is now fixed. The culprit was indeed C104, which after tracing out the PCB tracks turned out to be the capacitor immediately adjacent to the discriminator inductor T1013.

C104 (pictured below) emerged minus one of its lead-out wires and looking very sorry for itself, with a blue-ish crystalline deposit leaking from its base. Some of this had contaminated the board and had to be carefully removed with a drop of solvent on a cotton bud. A replacement capacitor restored normal operation, the voltage on pin 4 of the MC3357P is now back up to 6 volts and stable, and the squelch operates properly once again.

Many thanks to everyone for your interest and suggestions.

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Old 7th Oct 2018, 12:06 am   #23
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Default Re: Yaesu FT290R Mk 1 squelch fault

That's good news. I'm a bit late with this but I just uploaded my copy of the FT290R schematic to the link below.

I created this a few years ago by pasting together several images from somebody else's scanned pdf. My version puts them together like a Bayeux tapestry but without losing resolution. Sadly the original pdf wasn't great. Otherwise the quality would be much better. But the image is something like 4000 x 1000 in size and it is much nicer to navigate than having the schematic broken up into several sheets. Try zooming in to see the full resolution as a standard HD monitor won't be able to display it properly unless you zoom in to just part of the image.


I posted it up to one of the Yaesu groups a few years ago but thought it might be worth sharing here.
https://www.qsl.net/g/g0hzu//RF%20Tr...90_schem12.jpg
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Old 7th Oct 2018, 12:23 am   #24
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Default Re: Yaesu FT290R Mk 1 squelch fault

Thanks, Jeremy. I have the full-length fold-out circuit diagram that came with the rig. It seems that no service manual, component layout or PCB track layout has been published anywhere.

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Old 7th Oct 2018, 12:53 am   #25
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Default Re: Yaesu FT290R Mk 1 squelch fault

That PCB does look clean! I earlier dug out my old 290R and had a peek inside to look for C104 and I can understand why you started the thread. I'd forgotten how cramped this radio is inside and it was just too difficult to work out where C104 is located without further dimantling.
It really is a shame there is no parts layout diagram for the PCB.

My old 290R has sat unused for a long time now and is now full of black residue from the internal sponge. It looks to have rotted in some kind of way and I guess I'll have to clean it all out as it looks a real mess inside. I bought this on ebay as a non runner quite a few years ago with a low bid of about £35. Amazingly I won the auction and the fault was just the s meter was stuck over on receive due to an AGC fault. Otherwise it has a Mutek board in it and it worked fine after I fixed the AGC and aligned it all. However, I've never used it on air (i.e. transmit) in all this time! I keep meaning to put it in the car but never seem to get round to it...
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Old 7th Oct 2018, 1:33 am   #26
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Default Re: Yaesu FT290R Mk 1 squelch fault

Hi. Out of interest what did you do to fix the AGC fault?
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Old 7th Oct 2018, 1:47 am   #27
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Default Re: Yaesu FT290R Mk 1 squelch fault

I recall that the previous owner had already tried to fix the AGC fault and had left a mess with some parts soldersucked to isolate them and I think they gave up on it. I'm pretty sure I replaced the JFET Q1015 and a capacitor and cleaned up the mess left behind and it has worked fine ever since. However, I'm not sure this is a typical repair for this fault. It appears to be a common problem and I think the usual fix is to add a bleed resistor somewhere. But for this radio I just probed around with an ultra high Z DMM (several GigOhm input Z rather than 10MegOhm) and worked out what was wrong with this one. But I think there may be several causes for this problem and I may have just got lucky with mine as there doesn't seem to be a definite diagnosis for what causes it. Loads of people resort to fudging the circuit with a bleed resistor for example.
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Old 7th Oct 2018, 9:30 am   #28
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Default Re: Yaesu FT290R Mk 1 squelch fault

Quote:
Originally Posted by G0HZU_JMR View Post
I can understand why you started the thread. I'd forgotten how cramped this radio is inside... My old 290R is now full of black residue from the internal sponge. It looks to have rotted in some kind of way and I guess I'll have to clean it all out as it looks a real mess inside. I keep meaning to put it in the car but never seem to get round to it...
The layout is not made easy to trace because parts of the top of the board are hidden by the bundled wiring loom.

The black sponge had degenerated on mine too. I vacuumed the bulk of the remaining gooey dust away, then used some MEK solvent to remove the rest of the sticky goo. I stuck a sheet of paper over the inside of the lid.

I do sometimes ask myself why I keep this radio, and my many other 'vintage' ham radios. The usefulness of any single-band, low-power, non-CTCSS-equipped radio is questionable at best!
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Old 7th Oct 2018, 11:31 am   #29
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Default Re: Yaesu FT290R Mk 1 squelch fault

Well done on the accurate diagnosis and repair.

I keep my 290R2 partly because I've owned it from new and so we have a 'history' together, and partly because it is still the only 2 metre SSB radio I have. I have the official clip-on linear for it as well, so it is quite usable as a mobile radio. Most of my operation is simplex anyway.

At one time I used to carry it with me on every ascent onto the high fells in the Lake District, but the level of SSB traffic declined to such an extent that I often found myself carrying its not insignificant weight all the way up a hill for no reason. However, that was before the SOTA scheme kicked off, so it might well find a new lease of life on the hills now.
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Old 7th Oct 2018, 12:12 pm   #30
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Default Re: Yaesu FT290R Mk 1 squelch fault

Thanks very much! I've had it on monitoring S20 most of the morning. The squelch seems perfectly okay now. I have to check from time to time, as 2 metres is so quiet around here. In two hours I've heard one call...
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Old 7th Oct 2018, 3:13 pm   #31
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Default Re: Yaesu FT290R Mk 1 squelch fault

And did you answer it?!

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Old 7th Oct 2018, 4:13 pm   #32
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Default Re: Yaesu FT290R Mk 1 squelch fault

No... it wasn't for me! What you mainly hear is one station calling another specific station.

CQ calls on 2 metres are as rare as hens' teeth nowadays, although I did hear one this afternoon. I didn't reply to that either, because I don't happen to like the person who was calling.

Never mind, this little episode has sparked a bit of interest in using my vintage ham kit more often!
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Old 7th Oct 2018, 7:04 pm   #33
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Default Re: Yaesu FT290R Mk 1 squelch fault

I like the vintage kit as well and have a 290 Mk1 also. Straightforward, does the job and not full of menu driven functions you never need or use.

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Old 8th Oct 2018, 10:18 pm   #34
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Default Re: Yaesu FT290R Mk 1 squelch fault

Agreed, Gordon.

You might like the postscript to this story; I have left the radio running for the past couple of days while I've been doing some painting, monitoring the FM calling channel S20 and the squelch is still working fine. This afternoon a CQ call came in from M0VCM/P, which I did answer as he was up on top of Brown Clee Hill running just 5 watts. I received an RS 55 report from my 2.5 watts, with my radio sitting on top of the wheelie bin on the drive with just its built-in telescopic whip aerial extended.

It's probably fair to say that despite the oft-heard criticism that the '290 in its unmodified form was 'deaf', at least its transmit and receive capabilities were roughly reciprocal. Many people added the MuTek front end and subsequently found that they could hear a lot more stations, but couldn't work any of them!
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Old 8th Oct 2018, 10:59 pm   #35
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Default Re: Yaesu FT290R Mk 1 squelch fault

For the potential benefit of anyone else searching for this particular fault, I've posted a brief Success Story here.
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Old 9th Oct 2018, 11:15 pm   #36
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Default Re: Yaesu FT290R Mk 1 squelch fault

Perhaps the final post in this thread... thanks to John, who mentioned in his post #3 the vintage FT290 User Group on Yahoo. I have finally been approved to join, and sure enough there is a drawing of both sides of the PCB available to members in the 'files' section, as well as a recent detailed article covering the wholesale replacement of all the electrolytic capacitors showing component placements and values. One to bear in mind for future reference.
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Old 13th Oct 2018, 7:17 pm   #37
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Default Re: Yaesu FT290R Mk 1 squelch fault

Hi Phil, I'm guessing that you probably have the 290 all screwed back together gain now, but if it's still opened up, I wonder if you've done anything with the little bulb which lights both the frequency display and the meter?

Having just dug my 290 out of the cupboard, I find that bulb has failed, and a search of Google suggests this is common and is best dealt with by putting in a LED. There are articles giving a detailed description of what's involved, but unfortunately, getting at the bulb means lots of dismantling! .

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Old 13th Oct 2018, 10:37 pm   #38
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Default Re: Yaesu FT290R Mk 1 squelch fault

Hi Bazz. Indeed, it's all back together again. The bulb in mine had actually failed some years ago. I resisted the temptation to tackle that problem, largely because I have heard too many horror stories concerning damaged displays! It seems all to easy to end up with no display at all, so I thought it best to leave well alone, given that the lack of a backlight is of minor consequence.

Good luck if you plan to tackle yours, though! If you succeed and write about it, perhaps I will be encouraged to have a go myself...
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Old 14th Oct 2018, 12:00 am   #39
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Default Re: Yaesu FT290R Mk 1 squelch fault

I hadn't heard of displays failing, but on a piece of equipment of this age, that's not all surprising. It's a terrible bit of design!

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Old 14th Oct 2018, 12:11 am   #40
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Default Re: Yaesu FT290R Mk 1 squelch fault

I don't think the display 'fails' as such; it is just very easy to break it in the process of replacing the bulb
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