Faulty Resistor pack...

[Ron ZL1TW]

Hi ,
       Just been fault finding a K2 for a chap here. the problem was no V
bias-xfil , so the filters couldn't be set.  Nothing appeared to be coming
out of U10 on the Control board, and resistance values around it seemed
odd, so I gave the IC the chop. The resistances were still strange
....impossible in fact, and it appeared that both RP2 and RP3 might be
crook. Something that sounded too strange to be true. I took out RP2 ( 82k)
. Better, but still had strange readings, so out comes RP3 ( 47k) and the
readings looked like what one would expect with all the components removed!!
Metering RP3 showed it was not 5 individual resistances. They were all
joined together and ranged in resistance from 93k to 41k. In fact I was
getting a reading of 90k from pin 1 to pin 10......no wonder the poor old (
now deceased) U10 was not functioning.
Has anyone else been fooled by a crook RP?? It sure had me bluffed for a
while......
Incidently......RP2 was fine....but has rather short legs now...
Cheers.......Ron ZL1TW

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[Bob Nielsen]

On Mon, Oct 11, 2004 at 04:45:24PM +1300, Ron W wrote:

> Hi ,
>       Just been fault finding a K2 for a chap here. the problem was no V
> bias-xfil , so the filters couldn't be set.  Nothing appeared to be coming
> out of U10 on the Control board, and resistance values around it seemed
> odd, so I gave the IC the chop. The resistances were still strange
> ....impossible in fact, and it appeared that both RP2 and RP3 might be
> crook. Something that sounded too strange to be true. I took out RP2 ( 82k)
> . Better, but still had strange readings, so out comes RP3 ( 47k) and the
> readings looked like what one would expect with all the components removed!!
> Metering RP3 showed it was not 5 individual resistances. They were all
> joined together and ranged in resistance from 93k to 41k. In fact I was
> getting a reading of 90k from pin 1 to pin 10......no wonder the poor old (
> now deceased) U10 was not functioning.
> Has anyone else been fooled by a crook RP?? It sure had me bluffed for a
> while......
> Incidently......RP2 was fine....but has rather short legs now...
> Cheers.......Ron ZL1TW
>

What is the number on RP3?  Did you install one of the other resistor
packs by mistake (which I did in one case)?  Some of them are individual
resistances, while others consist of several resistors all tied to a
single point.

Bob, N7XY
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