[HECnet] No connectivity to arsgea 4

Fri Jan 22 10:12:07 PST 2021

I’ve not used SD cards in my Pi’s 3B and 4 for a while now. Most boot off USB to SSD drives and a bunch of 8 boot off read only SD long enough to boot the rest of the way over iSCSI.

Keith

> On 22 Jan 2021, at 18:05, Peter Lothberg <roll at stupi.com> wrote:
> 
> The KA has no switching power supplies.....
> 
> -P
> 
> ----- Original Message -----
>> From: "bqt" <bqt at softjar.se>
>> To: "hecnet" <hecnet at Update.UU.SE>
>> Sent: Friday, January 22, 2021 12:43:40 PM
>> Subject: Re: [HECnet] No connectivity to arsgea 4
> 
>> ...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