Kenpro KR-400RC dial spinning fault

[VK4GHZ]

Another year, another KR-400RC fault.
It just wouldn't be the same otherwise.



When the dial on a Kenpro K-400RC starts to spin around, all by itself, one might assume that the belt driving the dial has broken.
Not this time...

Now normally, semiconductors are designed into circuits to protect passive devices.
Right?

So one might assume that a transisitor or diode has failed.
Not this time either...


Above: R1, 220R, burnt out


Above: R2, 220R, burnt out


Above: R17, 820R, burnt out

Be aware that there is mains voltage going to the fuse on the PCB.
IMO, this open fuse is incredibly dangerous.
After being zapped once, during a previous repair, I then covered it with cloth tape.



I hope the later model "Yaesu" branded rotators aren't as primitive as these older Kenpro models.
Or are they?

[VK6OX]

Hi Adam,

Must be some sort of reverse karma happening....my KR-400RC controller has started playing up in the last day or so.
I've just pulled it apart some, and found that the little black drive belt is shot!

It appears as though you may have had this problem at some stage so my question (in 2 parts hi!): is there a "ready"
replacement belt anywhere, and what's involved in actually replacing it - i.e. do all the gear wheels have to come out?

Thanks in advance
73 Andy

[VK4GHZ]

...is there a "ready" replacement belt anywhere, and what's involved in actually replacing it - i.e. do all the gear wheels have to come out?

Andy, unfortunately, it appears DSE no longer stocks the belt drive kit.
Until I was made aware of that kit, I tried a rubber band, but that only lasted a few weeks.

I've had a look at the Small Parts and Bearing belt section, but they don't appear to have small diameter round belts.
http://www.smallparts.com.au/store/categories/belts/
Maybe a small "V" belt?

WES in Sydney have many belts for audio equipment: http://www.wagner.net.au/catalogue/05_Audio.pdf
(They have even more for VCRs, DVD players etc, in Section #4, but that they aren't referred to by size, simply the model number of the item it is intended for.)

Element14 don't appear to have anything suitable.

Jaycar have this kit http://www.jaycar.com.au/productView.asp?ID=HP0650, but you would need to take a look and see if there is anything close.
I don't remember the belt diameter, but you are in the best position to measure this now.

Maybe a search on eBay.
On-line searches of hobby R/C stores.

Yes, you will need to undo some of the gears to slip the new belt over, but again, I don't remember any specifics.
It was over 5 years ago now, so it is worth going to the effort of finding a suitable belt that can be used.
You can keep on enjoying your KR-400RC... until something else goes wrong with it!

Can anyone else suggest likely sources of belts, as this will affect all round controller users, sooner or later?

[VK6OX]

Thanks for the info Adam. I've dismantled the controller now, and the belt diameter is measured at 38mm (or as near as dammit given the belt's broken!).
Armed with this info, I'll do a bit of a hunt around tomorrow....may even have to opt for an -o-ring rather than a drive belt, depending on what's out there.

Will advise outcome here.

Cheers
Andy

[VK4GHZ]

Will advise outcome here.

Andy, please do.
They are a popular rotator, and I am sure others will be be following in your footsteps.
(Solutions posted on this forum are always well ranked with Google)

I got sick of repairing the old controllers. Parts flying everywhere, tiny little plastic spacers and failed belts.

Got a couple of these http://www.mds-ham.com/RC1-G-Digital-Rotor-Control.htm Very happy with the results

Hey Matt, they look interesting.
I was thinking only yesterday, that my next project might be a retrofit LCD replacement, using a graphic display like those.
Their pictures aren't that good, and it's difficult to make things out.
Are those the direction switches on the left?
Are they standard sized toggle switches?

Is this a self contained box that totally replaces the old round controller, or does it mount in the old controller somehow?
(Perhaps you could post a picture of yours sitting on the bench so we can get a better idea of this?)

[VK6OX]

Hi Adam,

I certainly will let everyone know how I go with a replacement drivebelt. There was an old thread (around 2008 I think) where someone used an o-ring from a bearing supplier to replace a belt in a different model controller, so this could be a viable solution.

As to the RC1-G digital controller, it looks like the swiches on the left (for CW, CCW) are momentary PBs, likewise the "Goto" PB immediately to the left of the knob on the lower right.

[VK4GHZ]

Excellent picture Matt... puts it all into context now.
Thanks for sharing.
An excellent solution, for when you've had enuf!

[VK6OX]

Excellent picture Matt... puts it all into context now.
Thanks for sharing.
An excellent solution, for when you've had enuf!

x 2!!

Thanks Matt!

[VK6OX]

Hi all,

rotator controller fixed...using a #029 nitrile rubber o-ring purchased from Mining and Industrial Supplies in Malaga (Perth suburb) for the paltry sum of $0.55...the rub is I had to buy a pk of 20!!!!!!!! The number 29 is a std imperial o-ring size and as such should be easy to source from all over VK.

If anyone wants one of mine, all you hv to do is work me on 6m, then send me a QSL card with SASE!!!

73

[G4FRE]

thanks for the hint on the size of the rubber rings for the KR400RC . I found they are available in the UK as BS029, which worked fine on my KR400RC. Mine failed after 26 years of use! As I had to buy 10, I also changed the one in my KR600RCl

Dave
G4FRE

[VK4NWH]

My KR-400RC has issues also. most of the time turning clockwise it gets to about 30 degrees north then the needles takes off anticlockwise till it hits south and wont turn no further. I can stop it sometimes by hitting the CW button rapidly until it turns back. Anyone come across this and found a fix for it?

[VK3XL]

For those who dont have a Mining and Industrial supply close by you could try here
https://www.ludowiciseals.com.au/