TS-820S Doesn't Power Up

[K9TW]

As Robert notes the service manual has some real issues. These fall into Grammar, In Complete Sentences, TYPOs, and most problematic items that are flat WRONG. Wrong test points called out, wrong voltages, and wrong signal levels.

If you do not have test gear you can do the Owner Adjustments listed in Sect 6 Maintenance in the Operators manual. Most of these adjustments are made using the Marker (Xtal Calibrator) as the signal generator and the S-meter as the peak detector. Can get rig working pretty well just doing these simple alignment/calibration steps. Need a 50uv source to cal the S-meter, but all else can be pretty much done as noted.

If you want to do a complete factory alignment using the Service Manual as Robert says there are several people who have compiled corrections to this manual. You will of course need the listed test gear or similar to perform this complete alignment.

Best suggestion I can give you is if you want to do this you need to carefully read the step and try to understand what it is they are asking, look at the circuit descriptions and block diagram and follow along on the schematic. If it makes sense to you as written and what the expected response should be then go ahead and perform as written. If the step makes no sense or you do not get expected response come back and ask. Focus on correct test point, correct voltages, correct signal levels. It helps of course if you have Kenwood hybrid experience and have good fundamental knowledge of how the receiver and transmitter sections work.

Robert is correct a complete re-write is in order but it would be labor intensive. Would need someone who is very familiar with the 820 and has an operational one that is pretty much near to factory spec who would dedicate time to try the re-written steps to validate them before the re-write could be published. I no longer have an 820 and have pretty much stopped working on them. I have been looking for a tech special with idea that I could use it to do the re-write along with the notes I have compiled, but the ones on Ebay suffer from auction fever! Terry K9TW

[W5CNW]

I know this is going to sound stupid. . . But, the problem ended up being a plug on the coil pack board had come partway out. Plugged it back in and it works fine! Fine, that is, except for the driver tube, which rapidly looses output after only a few seconds. And the microphone, which isn't the original, and I think has the wrong impedance. Maybe I'll just use the phone patch port for digital modes. . . Any advice on this thought? Oh, and the display still doesn't work, I'll tackle it next.

Thanks for your help!

[WB5WSV]

I assume you mean one of the connectors going to the coil pack baord. Well, the TS-820S has an endemic problem with the connectors coming off, especially when you take the outer case off. My favorite one is the relay on the bottom, which comes loose every time you take the bottom cover off.

The fading output indicates a weak driver tube.

The most likely problkem with the display - assuming the connectors are all hooked up - is simple light corrosion on the contacts. Take the whole thing out and clean the contacts with an electronics-safe contact cleaner, such as Deoxit, LPS-1, ACF-50, or CRC Electronic contact cleaner (NOT CRC Electro-Motive Cleaner!) The display boards are hooked togther with a unique blade system, but are easy to get out.

You will no doubt find that the CAR module is out of calibration; they always are - and that is one of the worst sections of the manual to try to use.

Good luck!

Robert
WB5WSV

[W5CNW]

Well, I cleaned the plugs on the display boards, and now two decimal points came on instead of one. Then, it occurred to me to actually take the cover off of the counter unit and clean the contacts on the boards themselves. . . We'll see how this turns out tomorrow. . .

Does anyone have a marked-up copy of the CAR unit section of the manual they could scan and email to me?

I just ordered a new 12BY7A yesterday, so I hope that will fix the fading drive problem (but hey, at least there IS drive!).

[W5CNW]

Now all 6 digits of the display light, but are acting very weird. They only show either 6, 7, or are blank, except for the first digit, which shows either 1 or 2 depending on the band. They do change in no observable order or pattern when I move the VFO knob. The DH button does freeze them, and makes the first two digits and first decimal point turn off. Is this a normal problem?

[AF6LJ]

I'm not an expert on the display module, my TS-820 is an S model....
I would think there are still possibly connector issues however I defer to someone more up to speed on the display module.

[K9TW]

Unfortunately this may not be " normal" but all too common. This is a problem typically caused by poor soldering with the plated thru holes. The Counter Assembly Unit consists of two boards. The Counter Mixer Unit and the Counter Unit. You can remove the assembly and the two boards and clean the varnish off the corners of the boards and reassemble and see if that helps, but in my experience it is most likely bad soldering on the plated thru holes and not poor ground plane connections or bad/dirty molex connectors.

Usually you will need to re-flow the solder on all the IC pins that penetrate the boards (all that you can access) and some people report good success by placing short pieces of wire thru the plated thru holes and soldering on each side. You have to be very careful not to bridge any pins so have some small size rosin coated solder wick on hand and a magnifier to inspect your work. Good Luck Terry K9TW

I forgot to mention you need to join the Yahoo Kenwood Hybrid Group. There are many knowledgeable owners of TS-820s on that site who can help you. There a very good technical folks here, but I think the Yahoo group has approx 3000 members and many 820 owners to call on.

[AD5ST]

On the digital display, my recent experience...

I was given an 820S this winter by a friend whose dad was a ham; he had bought it new and used it for probably a decade, but it had been sitting for quite some time. I had to pour the better part of a bottle of Deoxit (or so it seems) into the VFO because of dirty connection on the capacitor there...

A handful of other minor problems that were easily resolved, and it was up and working in a couple of evenings.

As expected the digital display was no good. Several rounds of cleaning every connector on the outside of the module and the connections between the two boards in the module made it work for longer, but it would always fail. The internet told me about reflowing the joints on the counter board, particularly the vias, so I reflowed every solder joint on the counter board. It would work for longer but eventually it would give up.

My eventual solution was to pull out the module. No digital readout, no problem. I intend to inspect it further and try to get it fixed, but for the meantime it's fine, especially as the 820S became my standby rig a couple of months ago with the acquisition of an FT-950. I jumped forward 30 years in two months there. Both are fine radios, the two best radios I've had throughout the years.

[W5CNW]

IT WORKS!!! The new tube fixed the drive problem, and I forgot to clean the contacts of both boards. . . It was one of those "duh" moments. Now on to the mic.

[AF6LJ]

Very glad to see it's up and running.
You will enjoy it...
I use my 820 every Saturday and Sunday morning on Seventy-Five.