TS990 : Pannes rencontrées

My TS-990S is out of warranty, over two years old, and I foolishly thought that paying so much money, it should work well for years.  When it was under warranty I had to return it to repair a failure in the main display, and that’s when I was surprised to have to pay $200 to ship it.  At least I didn’t have to pay for the return that time.

For some time now, when I turn the RF gain all the way up, it mutes.  That’s curious, but I can work around it.  That first showed up on FM, but is now SSB and AM.  When it worked, that is.

I very rarely even turn it on, and switch it off by the rear power switch.  Now both receivers give only the noise I would expect with no antenna connected, and even that mutes when I turn RF gain full up.  The radio grounds all four antenna connections when turned off, so lightning is unlikely.  The displays work, but the scope just shows the background noise level, and I can tune both receivers as normal.  There’s just nothing there on any band, or even the 590 KHz 5KW AM station almost in my back yard.

In 1961 I got my license and my background is repairing electronics 58 years now, including 36 years as a TV broadcast engineer, so I pulled the covers from the radio to look inside.  Kenwood’s documentation is quite good, and I have the detailed block diagram, enlarged to 4’ x 5’, hanging nearby.

Using a signal generator at 10 MHz (not the internal oscillator), I tuned the receiver to that frequency, still nothing on either receiver.  I found that the signal made it past the AM broadcast filter but not through the bandpass filters.  Further, I found that the filters are not getting their signals to control the relays to select them.  Further, I coupled 8.248 MHz loosely to the output of the IF traps, sweeping back and forth.  Still no signal.

I confirmed all the voltages on the DC-DC board.  The transmitter works fine on all bands.  (It doesn’t use the same bandpass filters.)

At this point, I’m about ready to park it in a corner and drag out my old Heath SB-102. Does anyone have any ideas?  I’d like to think I’ve missed a switch somewhere.  I don’t look forward to spending my whole pension to get it fixed!

Dave, WA4BRI

Update on Not-starting...
Master Reset did not fix the problem.
Removing both USB and LAN cables did not fix the problem.
Reload FW - will not allow a reload of the current FW.  Will not allow a roll-back to an earlier release.
Work around:
Leave the radio in the factory default "Instant On" mode.  Although I rather have my radio OFF when I turn it OFF but if Kenwood has the partial OFF as default I guess I don't have a problem with that.
I will be poking around a bit more as I think of alternatives.  But it is such a time sync to have to wait so long before the radio will come on.
A phone call to Kenwood is probably in order now too.
I have a lot of hours on this radio since March 2013.
73, Bob - W6OPO

KD7F a écrit:I just had a bit of a scare with my TS990. I was doing some testing in SSB with the power level set at 140W
into a dummy load and both LCD displays froze. The radio still would transmit and it sounded like the receiver
was working from the audio low level noise but I didn't switch to the antenna to listen for any signals (wish I
had thought to do that). Front panel controls seemed to work, although the LCD displays wouldn't show it as
they were frozen. I cycled power and the radio rebooted and acted normally (displays working again).

After further transmissions into the dummy load, I was unable to get the problem to repeat.
I wonder if anyone else has seen this behavior.

The freeze occurred in transmit mode, LSB with the power set at 140W on 75m. I was running firmware version 1.10
when the problem occurred. I have upgraded my radio's firmware to 1.13 now. Nothing was connected to the COM port,
any of the USB ports, the display connector or the LAN connector. I had an AC line monitor on the AC supply to the TS990
and no line voltage dropouts were detected. That's about all of the conditions I can think of at the time the problem
occurred. My 990's serial number prefix is B53.

I've had my 990 for about 2.5 years and have only seen one other unusual behavior. In that case the transmit drive level
dropped as was indicated by the ALC indication and both internal and external power meters. Adjusting the power level
didn't fix the problem. As I recall, set to 200w the output peak power was about 25w in upper sideband. The problem
persisted until I switched to FSK to see if the power was low there. It wasn't, and returning to SSB the problem was
gone. It has been over a month now and this problem hasn't recurred. I didn't try power cycling the radio in that case.
The temperature meter was indicating half scale so it shouldn't have been due to temperature protection.

I believe only the spectrum portion of the small display was frozen as it was showing the TX passband not the RX passband
when in receive.  When I cycled power, the small display showed the normal shutdown display while the large display remained
frozen until it went blank as the shutdown completed.  I use the low power shutdown mode.

73, Jim

Abnormal Transmit Signal Detection
La mise à jour logicielle V1.24 du 12 septembre 2019 corrige certaines fausses détections ERR-005C.

I worked many years with my TS-990 without any problems.
Last week I got several times Error 005C → .
The error goes away when shut down the radio and turn it on again.
But after few qso’s the error keeps comming up.

The manual says to do a full factory reset, witch I done.
At first sight it seems that did the trick but some hours later the error pops up again.
I did not do any software updates lately.
Harry - PA1H

I had the problem for several months , finally sent it to Kenwood uk.
It took them some time to find the fault .this is their report-System eventually verified.
Then failed permanently. Replaced Q7 (a2) & Q7 (b2) Pair on Final unit.
Before it finally failed they were shorting.
Unfortunately expensive repair, have had the rig back a month used every day no sign of the fault.
Regards, Morris G3TRV

I replaced the potentiometer with the control of the driver's quiescent current and the power stage,
and then adjusted the quiescent current of both stages according to the manual service.
Greg - SP8NTH

I have / had the same problem on 30m and then after some time 20m. I can live without 30m but not 20m so I took the covers of the 990 and the PA board is right on top.
I manipulated the two pots but that made no difference.

I then tapped on the relays gently, with the handle of the cross head screw driver used to undo the cover. Powered back up and lo and behold all good. The 990 has been operating perfectly for the past 3 weeks since then.

Whilst the covers were off I also noted the details printed on the relays. Purchased 6 of them from RS components. Delivered to my door for about $22 au dollars ready to put in when / if the error occurs again.

VK6DW

The relays :
RS code : 1347930
Design : ALQ112 Relay 1 R/T 12V
https://www.rs-particuliers.com/WebCatalog/ALQ112___Relais_1_RT_12V_dc_pour_Montage_sur_CI-1347930.aspx
73 QRO -  Philippe F1DUZ / FG4KH

Philippe
Suggest you also change VR3 VR4  
Final Transistor  My TS-990 failed due to R3
Cost me $400 for repair and $500 for shipping
Best Regards - Ralph Yang  BV2FB

Hello Ralph
OK for VR3 and VR4 , yes sure because this pot seems to be poor quality .
For the transistors I bough preventively a pair from Mouse not too expensive. After you do the job by yourself or with a good solder specialist friend.
Attached a part of the invoice for a matched pair
Best 73 -  Philippe

At FG4KH /FG5FI we have got this error message and we have solved the problem
In first we had the problem on 20m and 15m band so with some comments on this chat we have changed the relays in and out on the filter on the faulty bands .

We remounted the pcb and we found the problem on all bands but after a fine check we found that the output  plug was too much press into the plug of the PCB and the aim of the coax may touch the groud so we put out the plug only 1 mm and all is ok now .

I hope than I am clear with my english !!

Easy to find this relays at low cost around 4 euros and easy to change on the PCB. The only thing is to be really carefull with teh screws !! don’t drop one inside the transceiver it will be very hard to schake  bottom up !!

I can answer to all questions, have a check also on the post before , the problem of the relay is know by kenwood

I have also a TS990 here and I have no problem atm.

I have a problem with NB1 on the main receiver:-

The problem began a few months ago. Sometimes engaging NB1 caused a big drop
in signal level, perhaps 40dB or so. After a while, "sometimes" became more
and more frequent, and now it is "always". The LED in the switch illuminates
as it should.

It is only NB1 on the main rx. On the sub-rx it works as it should.

I strongly suspect a relay or relays, but I need help in identifying which
one(s). I can then look inside the radio and see if I consider it possible
for me to do a repair, or send the radio away for professional work.

Anyone had this problem before ? Or anyone good with circuit diagrams that
can help ?

Many thanks

John G4ZTR

La mise à jour logicielle V1.24 du 12 septembre 2019 corrige certaines fausses détections ERR-005C.

I  recently started having the 005C error code regularly as well.  After researching the issue here as well as on the TS-990S Facebook group I'm inclined to suggest replacing IC5 as a starting point.

One test I did was to monitor PA idle current (Id) as I keyed the transceiver at 150W for several seconds on each band (I don't remember why I used 150W).  I found that the measured Id on the front panel meter would creep up over time and once it reached about > 9 A I'd see the 005C error.  The power output and PA voltage was always stable.  Power cycling the transceiver brought Id back to the normal 6-7A range.

The 005C error didn't manifest for me until I became more active in digital modes.  On CW my transmissions were never long enough to drive Id high enough to fault.  This leads me to believe that my transceiver could have been afflicted with this for a long time before showing thy symptom, which could also be true for other TS-990S owners.

I have my TS-990S on a shelf in queue for me to fix it when I get around to it so I can't report a solution yet.  Right now I'm having too much fun with my TS-870S that I took out of the closet.

-Anthony, NO4P

It would be useful if those of you who have replaced IC5 can list ( if possible) the date code on the defective part. Not only will this be useful in troubleshooting but enough occurrences of a given lot code will be useful in getting Kenwood to own up to a "manufacturing defect" which may result in further compensation. Although along time ago I do remember a chronic set of PA decks in the TS930 which had defective through hole connections in the PCB for which replacement boards were supplied well after the warranty date. Now that was something like 25 years ago but you never know

Dave
NR1DX

First off I'd like to thank all of you who have responded. There would be only few reasons why the indicated current for the final transistors would creep up under operating conditions.   Note I am saying INDICATED current because we don't know if it is due to an actual increase in current for the load or a reporting error, because the monitor system is causing and error.
1 - The beginnings of thermal runaway in the transistors themselves
2 - Drifting of the Bias setting potentiometers causing increased idle current
3 - Defective components in the current monitoring system.
4 - Drifting of the value of the shunt resistors used to monitor Drain current for the finals.
It would be interesting to repeat the experiment that Anthony NO4P did while also monitoring the output voltage of IC5 the shunt monitor chip.
One thought I had but can't prove is that because of the heat generated by the final transistors, this heat propagated to IC6 or maybe the bias setting
resistors VR3/VR4, and thus the values of the resistors or the performance of IC5 changed affecting the reported current.
Now I realize I'm probably getting into conspiracy theory here.  Some on this list have actually had this problem and changed out IC5 and the problem was solved.  Since I don't have physical access to a TS990 just yet I can't corroborate any of this.  At this point I am only trying to help out a friend who has spent all this cash on a great radio and can't use it.
Cheers for now     and   Thank you a bunch guys and gals,

Karin Johnson

Wonder if anyone has any experience of the sub display flickering and going off?
Started happening on my 990 a couple of months ago.
It always comes back on (so far)
I had an issue with the display output socket (my fault to heavy handed) which had to be replaced by kenwwood UK and it started flickering not long after being repaired. I wonder if something is loose poor connection??
Thank you in advance for any help.
Regards Gerry - G0PWX

Hi Gerry!
I had very similar  problem with my TS990. I lost few verical line at start and after 5 minutes whole sub display become dark, no informations on it. Local dealer with long term maintenance experience find that thin flat cable was broken. After swapping it work till now.

Good luck with your!

Polde, S57U