[vcf-midatlantic] Help! Stuck bit

Dave McGuire mcguire at neurotica.com
Thu Oct 10 01:04:30 EDT 2019


On 10/9/19 9:54 PM, Dean Notarnicola via vcf-midatlantic wrote:
> Hey VCF peeps! I’ve got a Briel Altair replica that has a stuck bit on the
> front panel. I’ve verified that switch (bit) 5 lets me deposit a zero or
> one into any given memory address. But when I go back to examine it, it
> always show one regardless of the actual state of the bit. I verified that
> the switch is good, the led is good, and I replaced all the 74 series
> latches without effect.  There is a 220 ohm resistor in line with it that
> reads 216 ohm but that should be well within spec for a 5% resistor. I
> could replace it with a new 2%, but I’m not sure that would fix anything.
> Anyone have any ideas why this bit always lights when I examine it? Thanks.

  Hey Dean.  I don't know that circuit at all, but that resistor doesn't
sound like anything to be concerned about offhand.  If you point me to a
schematic I'll have a look.

           -Dave

-- 
Dave McGuire, AK4HZ
New Kensington, PA


More information about the vcf-midatlantic mailing list