[cctalk] Re: 1974 No Name Terminal

Thank you! I couldn't remember if I'd posted it here before, I've been off the list for a while. Because I don't know really anything about it, I'd been operating on the belief the power sent from the PSU was DC. So maybe that's my issue. There is a single 10 pin connector from the PSU to the motherboard. I tested for DC and found the following: Brown - +5V Red - +5V Orange - +5V Yellow - -16V Green - +16V Blue - -0.8V Purple - GND Grey - GND White - GND Black - -2.4V I'm not sure if the +16 and -16v need to be adjusted, or if they are that high because they don't have a load during my testing. The -16V is directly connected to the VEE on a nearby 1488, and I think the max voltage there should be -15V. The blue and black are the ones that didn't seem right. But, if they're not DC then maybe that's my issue. Also last night I found more cold solder joints, so maybe one or both are affected by that. I will test with my DMM as AC instead of DC and see if I get something there instead. Barring that, I'm working on a schematic of the PSU to try and figure out what it's supposed to be delivering. Like I said, very tempting to plug in, I suspect it may be just fine.. but.. there's a lot of chips to blow up here if I'm wrong. -----Original Message----- From: Brent Hilpert via cctalk <cctalk(a)classiccmp.org> Sent: Wednesday, July 5, 2023 9:11 AM To: General Discussion: On-Topic and Off-Topic Posts <cctalk(a)classiccmp.org> Cc: Brent Hilpert <bhilpert(a)shaw.ca> Subject: [cctalk] Re: 1974 No Name Terminal On 2023-Jul-05, at 8:25 AM, Brad H via cctalk wrote: terminal in the early half of the 1970s. It has little serial number stickers tucked around but they're all random numbers, nothing really lines up. A few of the boards have what appears to be serial numbers in the low hundreds. the voltages on two pins that seem off. What does 'seem off' mean? One possibility is they are a floating supply for the CRT heater. Not unusual in those days was just to have an independent 6.3 or 12.6 VAC secondary on the PS transformer dedicated to the heater and it often wouldn't be grounded. You could try checking between the two pins with multimeter ACV range. This terminal (this specific unit) was mentioned on the list 2 years ago: https://classiccmp.org/pipermail/cctalk/2021-February/thread.html#57808 2021-Feb-12 Mystery (unusual) 1973 terminal Around a dozen messages. In one of those messages I list & ref some of the more-significant ICs from the board photos.