Re: Phantom drive?

On 8 Nov., 19:19, Paul Förster <paul.foers...@xxxxxxx> wrote:
Hi,

On 2009-11-08 15:52:33 +0100, Paul Förster <paul.foers...@xxxxxxx> said:

... I was just curious and checked RP6, the 1k Ohm SIL resistor array.

... hmm, it's not RP6. I've exchanged that with a definitely good one
(tested before soldering in) from another board. It now shows the same
odd behavior on pins 4 and 6. And the old one which I have soldered out
shows proper 1k Ohm on *all* pins. It's interesting that a resistor
changes its value when soldered in. Or that'd mean there is some
parallel resistance which is lower (~670 Ohm)...
--
cul8er

Paul
paul.foers...@xxxxxxx

Hallo Paul,
to make the search more systematic please try to do the following:
1. check if you've connected something to the user port that's
fiddling arround with pin 9 which is shared with the ATN pin!

if no:
2. please check if it's OK after removing CR9,CR11-17. If yes, re-
insert one diode after the other (polarity must be correct!) or Simply
replace all with new diodes (could also be a 1N4148)

if no (do NOT re-mount the diodes so far!):
3. remove capacitors C88 and C94 and check if it's OK thereafter. If
yes, replace with fresh ones

if no (do NOT re-mount the capacitors so far!):
4. remove the CIA, U22 and RP6. Now all signals of the serial port
(except RESET) should not have contact to *anything* (with the diodes
and capacitors removed as well!)
In case you measure any Ohm-value < 100kOhms from any of the serial
signals to ground you have detected a shortage on the board.

see if that leads you any further...

Andreas


.

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