Don't neglect them while troubleshooting, especially the little red bastards. :-) My HP 2647A graphics terminal developed what appeared to be a sync problem when displaying more than one line of text. Swapping the suspect cards with known good ones from another terminal didn't change a thing. All self-tests passed, including text RAM and graphics RAM. Graphics mode worked perfectly. I finally swapped the two RAM cards (32K on each), changing the DIP switch configurations on each. At last, a RAM error. I excercised all of the DIP switches, put everything back together and it worked. This is the second time I've had problems with DIP switches in vintage HP gear. The other was in a 2117F I was working on for Dave McGuire. Same cure. Mike Loewen mloewen@cpumagic.scol.pa.us Old Technology http://q7.neurotica.com/Oldtech/
On Thu, 28 Mar 2019, Ethan O'Toole wrote:
This is the second time I've had problems with DIP switches in vintage HP gear. The other was in a 2117F I was working on for Dave McGuire. Same cure.
Contact oxidation?
That would be my assumption. Mike Loewen mloewen@cpumagic.scol.pa.us Old Technology http://q7.neurotica.com/Oldtech/
On 2019-03-28 12:56, Mike Loewen via vcf-midatlantic wrote:
On Thu, 28 Mar 2019, Ethan O'Toole wrote:
This is the second time I've had problems with DIP switches in vintage HP gear. The other was in a 2117F I was working on for Dave McGuire. Same cure.
Contact oxidation?
That would be my assumption.
As I was gathering hardware together for VCF-East I was just wondering about doing things like this as standard procedure -- reseating connectors and sockets. DIP switches and jumpers didn't occur to me. I feel this is probably subjective, but what do people think about doing this as a matter of course? I can understand "if it ain't broke, don't fix it" but it's also maddening to have strange intermittent failures that might be preventable. -- Jameel Akari
You would think that a little spray of "DeOxit" would be needed. Sent from: My extremely complicated, hand held electronic device.
On Mar 28, 2019, at 12:56 PM, Mike Loewen via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote:
On Thu, 28 Mar 2019, Ethan O'Toole wrote:
This is the second time I've had problems with DIP switches in vintage HP gear. The other was in a 2117F I was working on for Dave McGuire. Same cure.
Contact oxidation?
That would be my assumption.
Mike Loewen mloewen@cpumagic.scol.pa.us Old Technology http://q7.neurotica.com/Oldtech/
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