TS-440

[w8cbc]

I'll not pollute the Field Day thread any more with this. http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif

I dragged the thing in to work again today and set it up on the bench. As last night, it was operational when I took the lids off and turned it on.

I went after VCO5 this time. It establishes a reference in all modes and provides FM on transmit. Its control voltage was way out of tolerance high. I went looking for alignment tools and it had unlocked when I got back; its control voltage had jumped even higher.

I poked around at things looking for mechanical faults, messed with the goop in there, and then twiddled the core to bring the CV to spec. That got it working - but it was extremely sensitive to temperature. Breathing on it made the control voltage jump out of tolerance high (nowhere near as badly as before but still quite suspicious). Then it briefly unlocked again, CV jumped. I jabbed more components and managed to make it stay unlocked. More jabbing established that one resistor - R152 - was the culprit.

I pulled the PLL board and looked at the foil side. Sure enough, R152 had a bad solder joint. There were about five of them in the same general area. I redid all of them and looked around for more. That got me two more to redo - all within VCO5's shieldbox area.

I put the PLL board back in, let it cool to ambient, and measured. Now VCO5's CV was out of tolerance low. I readjusted and let it sit awhile. There was minimal change. Added heat and found that it is much less sensitive to it than before.

I then measured VCO1's control voltages. They were right where I had set them last night (high but within tolerance). I backed the adjustments down just a touch.

Then I did some general testing. Low-power transmit drew excessive current for a second then settled down. I don't need to be blowing fuses next weekend.

So I decided to get up the ambition and pull the final board. It wasn't as difficult as I had thought. The foil side didn't show anything obvious but that end of the bias reference diode did look just a little suspect so I resoldered it on general principles.

I put it back together one more time. It works. If I'm lucky, it'll keep working.

The moral of the story?

Thoroughly check 15-year-old gear after you pick it up, even if it's working. Had I done so in November, I would have probably avoided a few months this spring of intermittent exasperation.

[ve2nsm]

I fixed a lot of TS440s with the PLL unlock mode problem.
Permanent fix is to remove all the parts from VCO5, clean all the glue on the board and the components and resolder them in place.

It may seem like a pain in the a$$ but it really takes less than 2 hours, and if you put your mind to it, it's less than the time you screw around trying to adjust and fix and move and redo solder joints only to find that it's doing it again 1 month later.

[n8yx]

The R-5000 is also prone to this malady.

Have a pair of them; one was okay when delivered to me and the other was 'DOA' with a bad VCO. Chipping away the garbage and drying out the components was only part of the fix; I also found a bad resistor. Many notes I've read on the subject hint that the original potting compound is corrosive when wet...perhaps this is what did the resistor in.

Regardless...I have a bunch of spares headed my way in case I have to tear the VCO circuit apart and re-populate the board.

Also have a '440...it works FB. One of these days I'm going to set a '5000 and a '440 up as twins; muting, common antenna and RX slaved to TRX VFO (or vice versa). Having dual receivers available when one needs them is nice.

[w8cbc]

The point is taken. I'll save that procedure for next time. I have an unfortunate tendency to lose tiny things on the bench and/or forget where they came from.

---edit---

YX - that rotted resistor wouldn't be R146, would it? I noticed in the 440 that its leads were corroded-looking.

[n8yx]

Quote[/b] (kd8bsr @ June 21 2006,19:41)]YX - that rotted resistor wouldn't be R146, would it? #I noticed in the 440 that its leads were corroded-looking.
Not sure what the designator is in the R5000...but it was a 10K, 1/8w carbon-comp that provides base bias for the VCO buffer...I'll look this evening and edit this post accordingly.

[WA2ZDY]

Kenwood designed the TS440 for the "wealthy" US amateurs. The 940 was meant to be used at home and the 440 in the mobile. So in the 440, the VCO components were smothered with the potting compound for mechanical stability in the mobile environment.

After a given number of years, the potting compound breaks down and becomes a conductor, obviously causing the VCO to fail. As pointed out, the repair is getting all the potting compound off and replacing components as needed.

That's the story the guy at Kenwood in Virginia Beach told me when my 440 suffered this failure. And he told me that since Kenwood was "admitting" their faulty engineering was the cause, they were offering to do the $200 repair for $100. I rather thought they should do it for free but I was just a paying beta tester.

As I was sliding away from ham radio at that time I didn't fix the rig; I sold it to a friend who did the job and still has it on the air to this day. Aside from that one goofy engineering problem that 440 is a pretty good rig. Mine served me well for almost ten years.

[ai4ep]

http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif What years were the ts - 440 being made ?

There are at least 3 that I know of in Alabama that are working today, with no problems, so even if it was 1990 that was 16 years ago.

Not bad for Kenwood.
Even better for another brand
Excellant and rare for the third.

[WA2ZDY]

87 to about 95 or so I guess. Maybe later. Mine was an early one. I got it in 88. So thinking about it, it didn't last a whole ten years.

Kenwood did stop using that potting compound once they became aware of the problem. So the later rigs weren't affected by this. I'd be surprised to find 440s just coming up with this issue now. I would have expected these failures to have all occurred.

I suspect some of them are just being discovered now after periods of disuse, and in other cases, the potting compound is not actually the problem. Or perhaps some of these rigs are the ones that hams fixed themselves years earlier.

One guy was selling videotapes of how to fix this issue. He suggested scraping the gunk off the compenents that had been removed from the PC board and reusing the ones that could be salvaged. The Kenwood guy told me they replaced all the affected parts. So maybe those that were re-used are a problem now.

[w8cbc]

I gather then that they didn't use that goop in the '940?

As mentioned elsewhere, I ran into a fellow in 12 metres who was having unlock/warble problems with his 940.

My '440 was clean and had been used stationary with an amp. I suspect it had never been mobile or subjected to heat cycling until I got it.

15 years or so isn't bad I guess for something this complex.

For comparison:

The IC-751A had one of its VCO trimmers go south - a common problem. No other problems and performs better than spec. 15 years old.

The IC-271A has one flaky trimmer. It works but I should replace it. Needed some realignment. About 15-20 years old.

The IC-551D had lots of bad solder joints. Needed major realignment. There's more to do yet. About 20-25 years old.

The R7000 boards that I built two units from had many leaky electrolytics and transistors, also a bad limiter IC for FMw. About 15-20 years old, used by the USAF in Panama, i.e. banged around and subjected to heat and dirt.

So I'd say the TS-440 is about comparable to the ICOM gear in this regard. Each has its characteristic problems with age.

Bad solder joints are definitely something to look out for in all of them.

[AK7V]

Great thread. I have been thinking of getting one of these rigs, perhaps, and now I know what to look out for.

[ai4ep]

zdy ---so using 1987 as a furtherest year possible that it could have been---the total would be right near / almost / but not quite 20 years old ( including shipment time from production line to your friendly amateur radio distribution center. )

still not bad for a 20 year old rig...built back in the 1980 s

[WA2ZDY]

You're right Robert except the epoxy breakdown was a 7-10 year thing according to Kenwood. That's why I said I'd be surprised to hear that is a current problem at this late date. In theory all the TS440s that were made with the epoxy potting compound should have had this failure and repair already. Mine started failing - one VCO at a time - around 1994.

The later 440s that are at that age now were made without the potting compound and thus are not subject to this particular failure.

BSR. whether or not the rig was ever used in a mobile environment had naught to do with it. The potting compound broke down chemically over time and became conductive, thus shorting out the components in the VCOs.

The reference to mobile use was just a note on why Kenwood claimed the potting compound was there in the first place. Kenwood honestly believed that all US hams were wealthy and would buy a 940 for home and a 440 for mobile.

[ve2nsm]

This "potty" was in use extensively in a lot of electronic equipment, from TV to photocopiers since the end of the '70s. I have an old laserdisc player from 1979 which has that glue on the laser HV power supply. It was arcing all over the place when I had it http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif

The coumpound get flaky and conductive, it also gets darker with age and I think heat accelerates the process.

[w8cbc]

'ZDY - temperature cycling however may have made the difference. It's had to deal with temps down to -20C in the winter and up to 50C so far in the spring and summer (closed/locked car in the sunshine). That was my point.

Anyway. I put it back in the Polara this noon. It was about 40C in there at the time. It's been 32C and humid today, some rain, much steam. Those conditions would kill it dead in short order before yesterday. Today it's been just fine.

So I figure it was due to bad and intermittent solder joints. Recall that I mentioned its excessive heat sensitivity before I redid a bunch of them.

Now, if this fix was done by Kwd - would they have put some other sort of goo in there? I did see a couple of solder joints in the vicinity of VCO5 that looked as though they'd already been (very neatly) redone.

[WA2ZDY]

As I understood it they realised most hams didn't use the 440 mobile and the potting wasn't needed anyway. Mechanical stability of the components was a non-issue.

And NSM yes, potting has been used since forever in electronic stuff. Just most of it never broke down chemically the way Kenwood's did. This is why in the case of the TS440, it was an engineering FUBAR.

[w2vw]

The potting compound used in the TS-440 behaves differently in a humid environment. I have 2 here that need the glue removed (shoemaker's son with no shoes syndrome). Both work fine if left continuously on 24/7. The radios produce enough heat just sitting on receive to stay working. Once turned off, they will develop the "dots" problem within a few days. The problem is much worse in summertime. Anyone who has one of these on the edge of "glue unlock" might be able to get away with leaving the rig on until they get the time to fix it properly. Give the rig a day or 2 of operation to see if it will come back to life. The higher bands start to work first when driving moisture out.

[w8cbc]

Just what you said. Mine would gradually come back to life if I left it on awhile. Blowing the heater on it helped in the early spring.

I left it in the Polara overnight. It rained pretty good. So I'll find out today if I've really fixed it. Yesterday was encourageing.

---edit---

Yep, it runs just fine now.

Too bad propagation is in the tank.

[wa9cwx]

More stories of lives ruined by Pot.

http://www.qrz.com/iB_html/non-cgi/emoticons/sad.gif

[w8cbc]

It smoked the ionosphere pretty good today man. http://www.qrz.com/iB_html/non-cgi/emoticons/biggrin.gif

[WA2ZDY]

Dave, you sure do have humidity down where you are. I was living with my ex in the house in Manalapan when I had my 440 issues and she ran that A/C constantly, so I never saw the humidity connection. Ah well, at least you know what needs doing.

Nice call by the way. Good luck with it!

[w2vw]

Not only do I have the problem but my neighbor has the same exact situation.
Thanks for the best wishes on the call. If I get half the use that it's last owner got, I'll be more than happy.