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Hi, Raymond.?
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I have an SR780 and service manual with schematics.? But I take it you are in Europe.? ?I'm in Southern California, USA.? ?Let me see if I can scan a page or two with the microprocessor and video controller on it. Feel free to contact me via private email at jfordATieeeDOTorg. Jim Sent from my Verizon, Samsung Galaxy smartphone -------- Original message --------From: Raymond Domp Frank <hewpatek@...> Date: 7/28/18 11:12 AM (GMT-08:00) To: [email protected] Subject: [TekScopes] OT: Seeking help reviving a Stanford Research Systems SR760 Spectrum analyzer
The other day, I was given an SR760, presumably with a faulty CRT. I don't know where else to go for help, so I'm turning to you guys and girls. If someone can recommend a place to seek help, please do. As it is, I can find different versions of a Service Manual with component lists but no schematics. All SM's for SRS equipment from the same period come without schematics. Some have them mentioned in the TOC but that's all... I think that SRS won't provide schematics if I ask but I'll do that anyway. Maybe one of you happens to have something. Even a schematic for another member of the same family could do. I'm mainly interested in the digital part. The problem: The CRT seems OK but there is no video coming out of the video controller; a 64 pin DIL MC63484. The Chip Select pin is never toggled by the microprocessor (80C186). More significantly, 9 out of 10 times after a H/W reset the uP seems to remain inactive, although no NMI-, Hold- etc. pins are active at that time. The main oscillator runs and the Clock Out is always OK. 1 out of 10 times the uP generates addresses, strobes etc. - and a R/W signal but no Chip Select for the video controller nor several of the other peripheral chips. The H/W reset is clean and so are all power supplies. It seems obvious that the uP isn't running its intended program. This could be due to address decoding-, buffer- or latch- problems or even malfunctioning UV-EPROMS, which contain the program. A malfunctioning CPU seems less likely, although a missing data- or address- line or wrong level cannot be excluded. Almost all IC's are easily obtainable but I haven't found a shop around the corner that sells the 80C186. I haven't looked at things systematically yet with a Logic Analyzer (just a 'scope) but fully intend to do that since I think it's a nice piece of equipment, albeit with limited practical use to me. Schematics would *really* help though. Any ideas? Raymond |
