TS-440S assistance

[NE1S]

This may look kind of OT, but isn't really, because I mostly use my one & only ricebox, a Kenwood TS-440S, as a VFO & RF exciter for the PDM AM rig.

Anyway, last night I was using the TS-440S on 160M slopbucket (yeah, I know...), and it was working HI HI FB OM. I shut the rig down, and fired it back up to retune the antenna for tonite's Gray Hair Net on 1945 KHz. The frequency display came up normally, but in a few seconds the numerals tuned into just a series of dots (one per digit) at the bottom of the display, centered in each digit field. There was no RX audio, even before the digits disappeared, and I could not XMIT. Turning the VFO dial brought back the frequency display, but RX and TX were still dead, and the display returned to the "dots" after a few seconds. I could repeat these symptoms at will with the VFO knob or any of the keypad controls, but could not get the rig to function. I powered the rig down, then up, several times, and each time the symptoms were the same as I've described above.

Then this morning I powered up the rig just to see if it was still "broke," and it behaved normally. I did not try to use it other than verify that the display and RX worked OK, but did not keep it on for more than a minute because I had to get ready for work. But this was more than long enough for last nite's weirdness to exhibit itself.

I am operating it from the "matching" PS-50 power supply, not a battery.

I looked in the manual to see if this was a symptom of a dying microprocessor battery, but the manual said an "erratic" display, and since the VFO display would repeatedly display correctly, and at the correct frequency when "poked," I'm not sure if this  behavior  would be described as "erratic." Also, all the frequencies stored in memory were still there and correct. Last nite after the symptoms appeared I tried to reset the microprocesser per the manual and it indeed cleared the frequencies from memory, as it should, but the symptoms persisted.

That said, I bought the rig new in about 1987-88, and have never changed out the microprocessor battery (again, I know...) so will go ahead and do that anyway.

Anyone encounter this before, and know the solution?

Tnx in advance for any clues.

-Larry/NE1S

[Pete, WA2CWA]

You could try pulling and re-inserting all the interconnecting cables to wipe the contacts. You could have developed an intermittent in one of these connections Check the screws holding  the various boards to the frame. Kenwood was noted for not providing adequate ground connections between frame and board ground. A loose screw holding the board in place might be a problem. This was the cause of an intermittent frequency display problem in my TS-830. The encoder (I think the 440 has one of those)  in the VFO housing might have to be cleaned. The "poking stick" sometimes works wonders in isolating the problem area.

[WA1GFZ]

Deoxit all connections. I've fixed many dead radios by just removing all the connectors and boards and installing them again. Do not take an eraser to any contact or you will be sorry in the long run.

[n2bc]

The "all dots" display means the PLL is not locking.  I no longer have a service manual for the '440 but there is a PLL level ajustment that is the usual culprit.   

If that's not the problem, you may be on the verge of complete death for the rig. Early 440s had much of the PLL circuitry potted in globs of silicone.  Problem is that the silicone will eventually destroy some of the components.

If you GOOGLE on the symptom I'm sure you will find the adjustment and also many discussions of the potting compound and how some have removed it.

Good Luck!

73, Bill  N2BC

[Pete, WA2CWA]

You can also review this information to see what applies:
http://www.kb2ljj.com/data/kenwood/ts-440.htm

[flintstone mop]

Hello
It's a known bug in the TS440 and I performed the cure from the link provided a couple of years ago. That was an amazing model that sold well and held its value for a good number of years.
Fred

[KI4NR]

The PLL is unlocked, Specially the HET VCO. This is a normal problem with TS-440 I have service many of them. You have to remove all the synthetic potting material out of the HET VCO on the PLL board and the same on the main VCO on the RF board. It is a very time consuming project.You must remove both the PLL board and  RF board from the radio. To make it easier you can replace the resistors and electrolyte capacitors. It's better to replace some parts than cleaning the potting rubber from them. All other components must be cleaned. I have done countless many in the last few years in my shop. After you spend about 4 hours (that what it takes me, It will take you longer) doing the cleaning removing, replacing parts, Realign the PLL to Kenwood's spec. Also while you have the RF board out , replace all the 20 RX bandpass filter diodes as per kenwood's Service bulletin SB-974. These become leaky depending on the radio serial number. I replace them regardless, as standard procedure. If you do not want to tackle the project, I can do it for you at a very reasonable rate.

John KI4NR
LPC Wireless
http://www.qsl.net/ki4nr/

[NE1S]

Thanks a million for all the helpful comments and links, guys. I think I've got enough to go on now.

For now, the problem appears to have gone away, although I'm sure it's only temporary. Hopefully it'll last for a few weeks, because it'll be about that long before I'll have any free time to dig into this radio.

-Larry/NE1S

[WBear2GCR]

Larry,

Ya it is the "goo" that looks like "Pliobond" that Kenwoody put on the PLL sections...

It will return, at the time when you least want/need it to.
It becomes weather/temp/humidity sensitive.
So, fish out the board, get ur Xacto and dental pick out, and with a nice bright light and high-power magnifier and remove the crap from between the legs of the components and all over those little sections of board. After that it will work fine.

Take the board out of the radio.

Mine did not seem to require any realignment.

                   _-_-bear

[WA1GFZ]

sounds like the potting is added to deal with vibration. Removing the potting could make the radio a problem child in mobile applications. Not knowing the radio I prefer to find the problem and fix it rather than nuking the whole board.
Take Todd's KWM380 someone before me replaced a number of components without taking the time to understand the circuit. It turned out being a 270 pf cap but I bet 8 ICs were replaced. I start by looking at the phase detector output to see is the loop filter is stuck. When the loop filter is stuck in up or down compare it to the phase detector to see if it is in the opposite direction. Opposite direction usually means something in the loop filter is stuck and the phase detector is telling it to compensate in the reverse direction. If the phase detector direction and loop filter are in the same direction it is most likely an oscillator or digital problem. Study before you nuke.

[WBear2GCR]

It's the hardened goo...

They replaced the goo with something akin to hot glue in the later units...

Indeed it is/was likely for vibration control in the mobile.

I'd use something else, if it were my rig if I were going mobile for the "vibration control goo". Think that non-acetic acid cure silicone rubber would be ideal... GE used to call it Sil-Pruf. But if ur not mobiling then remove it. I'd remove it not matter what because the rig just won't work once it starts to conduct, which it does once the stuff gets old and hardens.

            _-_-bear

[WA1GFZ]

The MIL uses an RTV that doesn't eat copper. Still it is a pita to remove. If rice land uses the wrong stuff get it off the board or it will kill all the copper and make it green powder.

[KI4NR]

It is unnecessary to repot the VCO's The only one that exhibit's a little microphonics is the HET VCO and then very little, You have to beat the poor radio to death on a locked carrier to even hear it in SSB  mode. Kenwood just potted them to be on the safe side for all rough mobile condition the radio might encounter. I never pot them and never have a problem and I have done more than I can remember. If you just have to be anal & pot them (and only the Het VCO) the best is to use 5 minute epoxy that is thinned with a little 90% rubbing alcohol to form a thick varnish and just paint a little with a modelers brush on the sensitive frequency determining caps and Variactor diode. But really it's a waste of time ...

73's john

LPC Wireless
http://www.qsl.net/ki4nr/