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. Dean
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
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Dave McGuire -
Dean Notarnicola