[HECnet] No connectivity to arsgea 4

On 22 Jan 2021, at 18:05, Peter Lothberg <roll at stupi.com> wrote: ?The KA has no switching power supplies..... -P ----- Original Message ----- > ...despite Peter's experience with a KA10. I can't really comment on the > PDP-10s, since I've never worked much on them. But since I suspect they > might not have had switched power supplies, I'm not surprised if it > worked just fine, even after longer storage. > > The only 10s I have worked a bit more on is KL10. And replacing a power > supply for the MF10 was quite a job, since it was a linear supply with a > big trafo in it. *Very* heavy... :-) > > Johnny > >> On 2021-01-22 18:39, Johnny Billquist wrote: >> And speaking of power - the one thing that I have experienced a lot on >> 11/70 machines are the H7440 regulators. They tend to blow up. And >> especially if just kept in storage for longer periods, and then starting >> to be used again... >> >> Don't leave these machines off. That's all I say. That's when you get >> trouble. >> >> Johnny >> >> On 2021-01-22 18:36, Johnny Billquist wrote: >>> Not really trying to claim there is anything particular about DEC >>> equipment here. While they were built properly, I don't think there >>> necessarily is anything exceptional about them. >>> >>> But no, I do not believe any components have been replaced. One of the >>> biggest issue is when equipment are left turned off for longer times. >>> That usually seems to be the time when problems appear. These machines >>> are (or were) running 24/7, and have always done so. There might have >>> been one or another card replaced from time to time, since they were >>> on service contracts for a long time. But just by looking into them, >>> if something had been replaced, it was a long time ago. Based just on >>> the general look of the cards. >>> >>> By the way, we're talking 11/23 machines here. So BA23 box. Not that >>> much loaded in them, so no big strain on the power supply. >>> >>> My experience with 11/70 machines are the same. If they are kept >>> running, they usually just continue to work. If you have them off for >>> a couple of years, you'll have a lot of work before they are stable >>> again. >>> >>> But disk drives get into trouble with age, even if continually >>> running. And some are worse than others. The RD53 is sortof infamous >>> here... >>> >>> Johnny >>> >>> On 2021-01-22 18:15, Dave McGuire wrote: >>>> >>>> Sigh, yes, we all know of exceptions. But even then, I doubt it >>>> can be proven that those PDP-11 systems in production since the early >>>> 80s have never had components replaced. >>>> >>>> Not everything is built to DEC standards. That said, all my life >>>> I've been replacing chips, diodes, transistors, capacitors, and >>>> sometimes even resistors in DEC gear. It does happen, and it's not >>>> uncommon. >>>> >>>> The regulator bricks in the H742/H7420 power supplies tend to blow >>>> Zener diodes. That's fresh in my mind because we just lost another >>>> one at the museum recently. Those are failing with such frequency >>>> now that I've purchased stocks of the components that tend to fail. >>>> (we have a lot of those at the museum) And those ARE built to DEC >>>> standards. >>>> >>>> Speaking of not being built to DEC standards, I've got a Heathkit >>>> H8 on the bench right now, I'm repairing it for a new exhibit at the >>>> museum. Four failed (non-moving!) ICs replaced so far, it's very >>>> nearly done. >>>> >>>> -Dave >>>> >>>> On 1/22/21 12:03 PM, Johnny Billquist wrote: >>>>> Well, I know of PDP-11 systems out in production who have been >>>>> running since the early 80s. The only thing that fails is the damn >>>>> RD53... >>>>> Replaced those about 20 years ago now. The rest of the machine was >>>>> running just fine. At that at a steel mill, so not exactly a >>>>> friendly environment. Last I heard, things were still running, but >>>>> it might have been replaced by now. But anyway, it's the moving >>>>> parts that cause problems. The rest usually just keep running... >>>>> >>>>> Johnny >>>>> >>>>> On 2021-01-22 17:53, Dave McGuire wrote: >>>>>> On 1/22/21 11:41 AM, Thomas DeBellis wrote: >>>>>>> 10 years used to be nearly unheard of for retail machines with >>>>>>> moving parts. When nothing is moving, then supposedly there is >>>>>>> nothing to burn out. >>>>>> >>>>>> I don't know who told you that, but he/she knows jack point >>>>>> squat about electronics. >>>>>> >>>>>> Materials migration and diffusion across junctions causes >>>>>> semiconductor components to fail, tin whiskers cause shorts, some >>>>>> types of capacitors dry out and/or have their electrolyte >>>>>> deteriorate or crystallize, resistors drift, heat/cool cycles cause >>>>>> PCB flexure resulting in cracked solder joints, corrosion in air >>>>>> creeps into connector pin interfaces and forces pins apart, the >>>>>> list goes on and on and on. >>>>>> >>>>>> To be fair, some of the above-listed failure modes do in fact >>>>>> involve things moving, though imperceptibly so, my point stands. >>>>>> >>>>>> -Dave >>>>>> >>>>> >>>> >>>> >>> >> > > -- > Johnny Billquist || "I'm on a bus > || on a psychedelic trip > email: bqt at softjar.se || Reading murder books > pdp is alive! || tryin' to stay hip" - B. Idol