FT980 Repair, Restoration log

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Re: FT980 Repair, Restoration log

Postby WA6Q » Mon Oct 17, 2011 3:33 pm

Howard, try checking the RX against WWV (10 MHz) and switch between USB and LSB. If the tones and sub tones are different as you listen between the two modes carefully adjust the master TCXO to equalize the sound. You are adjusting the trimmer on the VFO unit directly at the master TCXO. Do you have enough pull to equalize the tones? If not you need to look at the padding cap (C10) on the VFO unit. These rocks are heated to a high temperature and have aged greatly over the years. The padding cap may need careful selection and the technical manual shows it to be 10 pF. This is not always true and selections were made by Yaesu to correctly center the rock when it was new 25 years ago. Using WWV will allow you to see if you have enough pull with the trimmer to center the master TCXO. This method is simple and a frequency counter is not required. The rig you are speaking about may have more than one issue however; be sure your master TCXO is correct. The entire chain requires an accurate master reference in order to correctly function.

Francis, go to the RF unit and identify relay RL1001. This little cutie is one of the relays that close on power up of the FT 980 in RX. You can clean it but, you must have the hands of a master watchsmith. The old part number M1190027 was changed in March of 2010. The NEW Part number is M1190082 and is still available. Try looking at this part prior to anything else. I've had success cleaning these with DeOxit and carefull paper burnishing between the contacts. It's very delicate but, it can be done. I've seen three FT 980's that required this TLC proceedure.

I hope this information helps.

Sorry guys....I'm having a heck of a time keeping the wolves away from the front door. This national economic situation is a major issue with me and it's not allowing me to complete this project.

Again...I promise to post all my stuff including bitmap's as soon as I can get my poop together.

Cheers,
William WA6Q
HF Equipment is: FT-900, FT-980, FT-990 and full Collins S-Line w/30S-1 VHF/UHF Equipment is: Two fully loaded 736R's and of course mobile rigs are: FT-8800 and (brand X)-Alinco 220...Yaesu doesn't make 220 stuff. :(
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Re: FT980 Repair, Restoration log

Postby WA3GGV » Tue Oct 18, 2011 11:43 am

William,

Thank you so much for the info on that relay, I will go and take a look at it. There is a shop in Atlanta (75 miles away) that a guy just had his 980 in for a "tune up".... I might just have to do the same thing when I get some extra $$$ to flirt with!

Francis/WA3GGV
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Re: FT980 Repair, Restoration log

Postby Howardk0acf » Fri Oct 21, 2011 6:13 am

Thanks for the reply William...Have done as you suggested & did get the ticks to sound the same on LSB & USB & the tones very close...Still have the problem of the LSB sounding high pitched like listening thru a can & USB sounds great. If I rotate the IF shift about 5 clicks counter clockwise LSB sounds great but on transmit it sounds like I am talking in a can. I love the monitor feature as I can listen to the signal when transmitting. Have to put the IF shift back to 12:00 to use USB & it works great. Wish I knew just what the original problem was & what the Ham did to it besides reversing 2 transistor,PNP in NPN place & NPN in PNP place. The voltage on TP4001 on the PLL board is at 4 vdc with full counter clockwise of IF shift & when rotating it to full clockwise position & going to LSB will only drop 4 tenths of a volt. If I adjust it to 6 volts like the Tech Manual says to adjust it to, the voltage only drops 4 tenths when USB is selected & IF shift full clockwise. If I shut the radio off then turn it back on the BFO is dead & voltage is 1 vdc at the testpoint. Have to adjust it to 4 vdc & leave it there to keep the radio comeing back up if shut off. I did notice that all the filters are installed in the rig with Fox Tango filters & the original stock filters were removed. I am wondering if the SSB filter could be bad??? but don't have equipment to sweep the filter. LSB is the only problem with the rig now. All the other modes work great. Where can I get the install instructions for the FoxTango filters & specks in case he installed the SSB filter wrong...Sure do appreciate the help very much...Howar K0ACF
k0acf
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Re: FT980 Repair, Restoration log

Postby WA3GGV » Tue Nov 08, 2011 1:36 pm

Well, my s-meter is now working just fine..... that relay was the problem and now that it has been used a number of times the receiver section along with the s-meter seems to be working just fine now. I now have another question...... what would be the easiest way to tap into the audio of the receiver? I work RTTY and need to tap into the audio section (while still being able to hear what I am listening to) and feed it into my TU. My last rig (Swan 350) I just went directly to the speaker in the PS enclosure and tapped it that way..... probably not the best solution, but it worked. With this 980 I just don't know.
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Re: FT980 Repair, Restoration log

Postby GM0PLH » Tue Feb 28, 2012 4:26 pm

I need some help to fix my FT980. The radio have the same problems with USB/LSB receiving . very high pitch on both !
I had adjust the BFO votlage on TC4001 at TP4004 . The votlage on full countercockwise is 6.05 V on USB and 3.98 V on LSB full cockwise !! But the audio still not copy . I also check the 30MHZ is fine ! I dont know why ! Can someone give me some inforamtion !!
Thanks for your help
Joe
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Re: FT980 Repair, Restoration log

Postby VE3CEA » Mon Jul 09, 2012 6:53 pm

Good day all,

I have a FT-980 that I picked up used that I have been nursing along to better health and it has, aside from some intermittent metering issues, been behaving generally well. However, a little while back, I started to have issues with the tuning having garbled reception right at the edge of the 500 Hz step of tuning in LSB. I recognised it as a PLL out of lock issue and touched up the tuning for the VFO. It took a little to get it to the happy point where temperatures in the rig didn't push it into instability at lock limit edge, which told me I have more future work, but I wanted it back on the air so it had to do. The problem appears to be hard fault now, easier to find in theory. Tuning is now acting in 1 kHz steps, as heard on the speaker, so the fine tuning stage of the VFO was showing fault. Logic is functioning to the VFO board to the affected stage ok. Frequencies appear to be all ok up to the output of Q05 which is at about half the frequency and with TP05 at a hard limit of 8V. I did spot TP 05 jumping limit to limit on inital warm up at random. No cold/poor solder joints were spotted on board inspection and no obvious damage to components on initial inspection. The output of Q07 seems dead to Q01. I am uncertain what should be expected at that point in the circuit, low frequency phasing singal or rf level output.

Before I start the part hunt, as this rig is getting up there in age I expect some parts to be obsolete. Has anyone run into typical problems on this board that knock the fine tuning VFO stage out of lock? Just looking to save a bunch of troubleshooting time as I seem to have one of those lives where work and other peoples broken stuff just seem to get in the way. :(

Thanks for any assistance,

Chris VE3CEA
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Re: FT980 Repair, Restoration log

Postby VE3CEA » Sun May 12, 2013 6:13 pm

well some progress,

Ebay came to the rescue with some parts. Swapped out the defective board for another and it is working again. Also was able to get a replacement handle for the rig and a replacement knob as the band had disappeared at some point in its life. Now I just need to track down a replacement foot for the front and I think it can go into full service again. I may still try to locate the parts for the other VFO board, but it is not a rush now ( not that I was rushing before :lol: )

Oh! any word from WA6Q??
Still watching for the info.
Chris
VE3CEA
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Re: FT980 Repair, Restoration log

Postby N8YX » Sun Jun 09, 2013 2:29 pm

I now own two of these radios. One has a few minor problems which some eBay spares ought to cure; the other is rock solid.

The '980s replace a pair of Kenwood TS-940SATs. Both platforms are good, but the Yaesus make more sense in the current shack configuration. One has a modified FTV-901R attached and is used for voice/CW duty while the other has an FC-757 and will be used for digital modes when its controller computer is finished later this summer.

The first of the two has a reference oscillator whose crystal has drifted to the point that I cannot net it properly, and I've had to sub a crystal which takes roughly an hour to settle onto the correct frequency. Does anyone have a spare BFO Board or a 30.0000MHz HC-18/U crystal they would consider selling?
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Re: FT980 Repair, Restoration log

Postby kg4eyg » Mon Dec 21, 2015 6:23 pm

does anyone know of someone that can align a FT-980? Mine works very well. It is not off frequency at all, but having an issue with RF out. It seems all my other radios, when using my Palstar tuner, tune down to one to one. but it seems this radio limits power unless I accept 1:3 SWR, then it seems to allow full out put. Not sure if the power limit circuit can be adjusted or bypassed. thanks
Art
KG4 EYG
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Re: FT980 Repair, Restoration log

Postby N8YX » Fri Feb 03, 2017 9:18 pm

Bumping the thread a bit:

A couple of posts up - and a couple years back - I mentioned that I had gotten a '980 whose 30MHz reference oscillator drifted quite a bit and that I was searching for a replacement board. Shortly after that post was made, I had trouble with my other '980 and the FC-757AT which was hooked to it. Namely, the tuner started rapidly switching itself in and out of the feedline circuit. The only way to make this stop was to kill the radio's AC power (the tuner is powered by the '980 12VDC supply when connected via the special patch cable). After disconnecting the tuner from the rig and inspecting it, the rig now "thought" that 80M was a "Gen VFO" band - and you couldn't switch between Ham or Gen when on 80M. The rig also appeared deaf under 8MHz.

The other '980 still drifted while warming up. In addition, for about 15min only the 5KHz Up/Down buttons would tune the rig - and regardless of which setting the Mode switch is in at power-up, the radio came up on CW-W. After a thorough warmup, all was operational - VFO, Mic Up/Down and front panel Up/Down controls tuned it just fine. Puzzling. There were a few other glitches.

I thought long and hard about selling both of these radios for parts...then bagged them up and put them underneath a workbench in my lab. Fast forward to a couple of weeks ago, when I was moving things around to clean the storage areas. I got them out, connected each to power and antenna and began to take inventory of the faults present with each. They began to grow on me again, possibly due to their being similar in design - analog-wise - to another favorite series, the FT-90x. Maybe I could fix and enjoy them.

The "Gen" problem (#1) rig:

Digging through the Technical Supplement, I began to suspect the RF Board and its Band Filter I/O lines. If something had gone amiss with the FILT lines on the ACC connector the associated logic might very well have been damaged. I took the RF board out of both rigs and put the one from the "Tune Problem" (#2) rig into #1. Problem persisted...though I found that #2 RF Board came with the Yaesu General Coverage TX Mod, including TX Buffer Board. I'll post some notes regarding that board later in the thread.

Next step - after tracing the various logic flows - was to try a CPU Board swap. I had bought one some time ago in anticipation of using it to try to fix rig #2, so I removed the VCO/PLL Board, the original CPU Board and installed the spare CPU. After reinstalling the VCO/PLL Board, the rig was powered up and checked. Problem fixed. So...whatever was "wrong" was isolated to the original CPU Board. The defective board definitely plays a part in the repair of rig #2, though.

To be continued...
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Re: FT980 Repair, Restoration log

Postby N8YX » Mon Feb 06, 2017 3:17 pm

The "Tune problem" (#2) rig:

This one made its way to my shack several years ago (around the time I posted a 'want' looking for another BFO Board). In addition to the reference oscillator being way off frequency, the radio exhibited a problem when cold in that only the 5KHz Up/Down buttons would tune it. After a warm-up period, though, all worked (somewhat) normally: A Mode change required you to hit one of the 5K buttons before the VFO or other tuning means would work.

If one searches around the Internet, at least one other has person reported this condition with a '980. Perhaps theirs was the rig which ultimately ended up at my doorstep?

On to the repair:

Studying the service manual for possible fault areas, two become evident. First is the Dial Board. Second is the CPU Board and the D8279C Keyboard Decoder plus peripheral circuitry. I sourced a spare Dial Board (and promptly misplaced it!) so the CPU Board became the area of focus. The CPU which was removed from Rig #1 has a working 8279C mounted to it, so the chip was removed and swapped for the one in the defective rig. Problem persisted. I went for broke and swapped #2's CPU Board with the one I had previously removed from #1. This fixed the tuning problem, but now the "Ham/Gen" VFO bugaboo was present. Another study of the circuit showed the Band/Mode Decoder IC - a D8255C5 - as a possible cause. This particular chip is the center of the three large socketed ICs. Swap for one from the original #2 CPU Board, and...problem solved. (Keep this IC in mind any time your '980 develops band/VFO switching faults similar to what I've described in my post above.)

All the above work doesn't address the issue of "why" the tuning fault condition occurs, so here's what I think is occurring:

CMOS gates don't 'fix themselves' upon warmup; they tend to stay bad if faulty. And the protracted warmup-before-functional interval - at least 15min in all cases - suggests something other than an intermittent solder joint. Given the fact that the Keyboard Encoder doesn't appear to be processing Up/Down tuning pulses (or certain switch states, for that matter) until the warmup has completed, I started looking for possible analog causes around the area of the circuit.

One became readily apparent: On the Reset line from the 80C85 to several other ICs is C43, a 10uF tantalum. It's nearest Q25 electrically - connects to one of its Input lines - and is isolated from the other bus logic by a 560 ohm resistor in series. The "non isolated" side also controls the actions of Q10, a D-type flip-flop that interfaces with (you guessed it) circuitry which processes the Up/Down pulses.

Though I haven't swapped it yet, I have a strong suspicion that particular capacitor is the root of the CPU Board's evils. There are two other tantalums used on the board: C02 and C109. These are for de-spiking of the +5V line nearest their respective ICs. Plan is to change all of them out and test the board out the next time I have occasion to do a CPU swap in one of my '980s.

Definitely wouldn't be the first time that a tantalum cap has caused problems with gear I've repaired. Not by a long shot.
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Re: FT980 Repair, Restoration log

Postby N8YX » Sat May 06, 2017 5:44 pm

Bumping this thread up a bit.

I now own four (count 'em) of the things. A couple of fixer-uppers in addition to the two I posted about previously.

Has anyone reading this thread gone through the ALC alignment procedure and gotten the rig's Drive control to accurately control power output with the pointer set above 11 o'clock? If I turn the control to maximum (as the Tech Supplement indicates)then perform the ALC setup per the manual I'll get the spec'd power out - but if you reduce drive with the control from full CW back towards CCW, the power level will dip then creep right back up. Only when the Drive control is below 11 o'clock can the power be reduced without creeping back up to maximum (100w) and below this the output is stable at whatever level you select.

The RF Board and PA Assembly were swapped between two rigs (one at a time) and both exhibit the condition. This possibly rules out the CM Coupler and Protector circuits, and the CM Coupler in each has been correctly nulled via TC9001.

One wonders if the behavior is 'normal'.
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