Well, my last working DEChub 90 power supply is no longer working. It only
allowed for a terminal server, but, that can be useful.

Anybody know what to look for to fix some of these units?

Yeah, I know, switches are easily found and cheap. But, there is that terminal
server ...

--
David Froble Tel: 724-529-0450
Dave Froble Enterprises, Inc. E-Mail: davef@tsoft-inc.com
DFE Ultralights, Inc.
170 Grimplin Road
Vanderbilt, PA 15486

On Tuesday, September 5, 2023 at 7:52:29 PM UTC-7, Dave Froble wrote:
> Well, my last working DEChub 90 power supply is no longer working. It only
> allowed for a terminal server, but, that can be useful.
>
> Anybody know what to look for to fix some of these units?

Favorite failure of just about any power supply lately, or not so lately,
is electrolytic capacitors.

> [...] DEChub 90 power supply [...]

5V (and/or 12V) at almost any desired current should be easy enough
to find in a non-authentic package.

> [...] But, there is that terminal server ...

How many gizmos (what actual load(s)) are you trying to support?

I have a few DECserver 90 units running on some generic 5V, 2A (or 3A
or 4A) supplies. I believe that I used old mouse cables to get the
right (or close-enough) mini-DIN connectors.

> [...] electrolytic capacitors.

They're usual, and in many cases a bulging case is a good indicator
of a bad cap. But other devices fail, too, from time to time.

Den 2023-09-06 kl. 04:52, skrev Dave Froble:
> Well, my last working DEChub 90 power supply is no longer working.  It only
> allowed for a terminal server, but, that can be useful.
>
> Anybody know what to look for to fix some of these units?
>
> Yeah, I know, switches are easily found and cheap.  But, there is that
> terminal server ...
>

Is it a "non-matching connector" issue?

If not, there are many "Serial Device Servers" from Moxa.
I have played with them and they (from VMS) looks and works
just as any "terminal server".

https://www.moxa.com/en/products/industrial-edge-connectivity/serial-device-servers

On 9/6/2023 1:19 AM, Steven Schweda wrote:
>> [...] DEChub 90 power supply [...]

> How many gizmos (what actual load(s)) are you trying to support?

That gets to the heart of the matter. I have a DECserver 90M terminal server,
used with a dot matrix printer, that I've not used for many years. Probably has
ink all dried out. I'll most likely never use it again. So I really don't need
the DEChub90 nor the terminal server. But, it's perhaps nostalgia, more than
anything else. Anytime anything breaks, it seems like I'm breaking also.

--
David Froble Tel: 724-529-0450
Dave Froble Enterprises, Inc. E-Mail: davef@tsoft-inc.com
DFE Ultralights, Inc.
170 Grimplin Road
Vanderbilt, PA 15486

> [...] So I really don't need the DEChub90 nor the terminal server. [...]

I was more concerned with the number of occupied slots on the DEChub
than with the number of peripheral devices. If I had a DEChub with one
DECserver 90M and seven empty slots, and a bad power supply, I think
that I'd be looking for a 5V, 2A (or more) power supply and an
appropriate connector (as on an old mouse?) to replace the DEChub.

In fact, the last time I found an Ebay bargain on a pile of
DECservers (and some other less useful slabs), they came with a
DEHUB-AX REV B01 with an H7876-AA attached. Which I've now had for some
years, and never plugged in. If you're crazy enough, I could try it
out, and see if my power supply is better than yours. But, as I said,
for one DECserver, I'd discard the enormous DEChub, and get a little 5V
power adapter for the now-loose DECserver.

Dave Froble <davef@tsoft-inc.com> wrote:
>Well, my last working DEChub 90 power supply is no longer working. It only
>allowed for a terminal server, but, that can be useful.
>
>Anybody know what to look for to fix some of these units?

How did it fail? Flashing lights? Or worked fine, but then when turned off
it refused to turn on again?

Most of what goes wrong with supplies of that era are electrolytic caps, and
I am inclined to just replace them all with modern 105C types before even
starting to do diagnosis because leaky capacitors can make diagnosing other
problems more difficult. As long as the transformer windings aren't open
and the power transistor isn't shorted, it's likely not hard to diagnose.
If the power transistor is shorted there will be a lot of collateral damage
to track down.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Tuesday, September 5, 2023 at 10:19:45 PM UTC-7, Steven Schweda wrote:
> > [...] DEChub 90 power supply [...]
>
> 5V (and/or 12V) at almost any desired current should be easy enough
> to find in a non-authentic package.

Single voltage external power supplies are usually easy to find.

Near me, there is a used computer store that sorts them into bins
by voltage, so easy to find. Otherwise, they are easy to find it stores
like Goodwill, but you have to find the voltage yourself.

If needed, I cut off the old plug and splice it onto the new one.
But nicer to find one with the right plug already.

For more specialized ones, especially more than one voltage,
I would probably try to fix it.

> If needed, I cut off the old plug and splice it onto the new one.
> But nicer to find one with the right plug already.

The problem here is that the DEChub Work Group Units (such as the
DECSserver 90M) have two connectors for power: a two-row x 16-pin
male odd-ball, and a 7-pin female Mini-DIN. The DEChub backplane uses
the 32-pin odd-ball; the individual-unit supply (which I don't recall
ever seeing) uses the Mini-DIN.

https://manx-docs.org/collections/mds-199909/cd2/network/dehubom1.pdf

I'd expect that finding an adapter with either of these is unlikely,
at best. What I use is a spliced-on cable with an 8-pin male Mini-DIN,
which seems to be close enough. (The extra pin on the 8-pin male falls
neatly into the keyhole of the 7-pin female, contrary to the impression
given by the picture here:)

https://en.wikipedia.org/wiki/Mini-DIN_connector

According to that article, PS2 mice used 6-pin connectors, so it's
more likely that I got my 8-pin stuff by bisecting some kind of
serial-modem cables. It's been a while, so I don't remember what I
chopped up to get the 8-pin male Mini-DIN.

> For more specialized ones, especially more than one voltage,
> I would probably try to fix it.

Most of the Work Group Units use 5V only. A DECrepeater 90T+
(-DETMR-N), or a DECserver 90TL (-DSRVE-M), or a DECserver 90M
(-DSRVH-M), for example, says "5.1Vdc 1.8A, 9W". The DECrepeater 90TS
(-DETMI-M) is one of the few which also wants 12V (under some conditions
or other?). It says (confusingly):
1.2 A @ 5V
0 A @ 12 V
0.5 A @ 12 V W/AUI 6 W

On the bright side, my power supply seems to be able to power a
couple of Work Group Units without generating any smoke.

On Wednesday, September 6, 2023 at 11:06:43 PM UTC-7, Steven Schweda wrote:

(snip)

> (-DETMI-M) is one of the few which also wants 12V (under some conditions
> or other?). It says (confusingly):
> 1.2 A @ 5V
> 0 A @ 12 V
> 0.5 A @ 12 V W/AUI 6 W
Makes some sense. If the AUI port is used, it needs 12V.
It if isn't used, it doesn't.

When Apple wanted to use AUI ports, but didn't have 12V, they designed
AAUI. (That is Apple AUI) which uses a different connector and 5V instead
of 12V.

Some have a switch to turn on/off the AUI port. Some sense the current load
and turn it on.

> On the bright side, my power supply seems to be able to power a
> couple of Work Group Units without generating any smoke.

I had one device that generated very bad smelling smoke.
That is, the phenolic smell that many recognize as burning
electronics, and others as hospitals.

I put it in a sealed plastic bag.

On 9/7/2023 1:06 AM, Steven Schweda wrote:
>> If needed, I cut off the old plug and splice it onto the new one.
>> But nicer to find one with the right plug already.
>
> The problem here is that the DEChub Work Group Units (such as the
> DECSserver 90M) have two connectors for power: a two-row x 16-pin
> male odd-ball, and a 7-pin female Mini-DIN. The DEChub backplane uses
> the 32-pin odd-ball; the individual-unit supply (which I don't recall
> ever seeing) uses the Mini-DIN.
>

I got one (individual unit supply), an H7867 dual voltage 5/12v which came with the pile of DECservers and DECrepeaters mentioned below. It's just a small, thin(ish) rectangular beige brick.

> https://manx-docs.org/collections/mds-199909/cd2/network/dehubom1.pdf
>
> I'd expect that finding an adapter with either of these is unlikely,
> at best. What I use is a spliced-on cable with an 8-pin male Mini-DIN,
> which seems to be close enough. (The extra pin on the 8-pin male falls
> neatly into the keyhole of the 7-pin female, contrary to the impression
> given by the picture here:)
>
> https://en.wikipedia.org/wiki/Mini-DIN_connector
>

By golly, you're right. I never noticed. Here is a spec sheet for a series of Mini-DIN connectors and it clearly shows what you mean.

https://www.mouser.com/datasheet/2/222/kyco_s_a0000255670_1-2271771.pdf

Mouser has 1100+ of the 7-pin ones for $1.56 (quan:1, $1.42 quan:10). I just ordered a few as I have a small pile of DECserver 90M's I got on Ebay and they all need power. Taking this connector and a 5vDC regulated wall wart is all they need. With the diagram on VCF it should be an easy job.

https://forum.vcfed.org/index.php?threads/looking-for-decserver-mneng2-sys-mneng3-sys-and-mneng4-sys-boot-files.62810/#post-773655

> According to that article, PS2 mice used 6-pin connectors, so it's
> more likely that I got my 8-pin stuff by bisecting some kind of
> serial-modem cables. It's been a while, so I don't remember what I
> chopped up to get the 8-pin male Mini-DIN.
>

I think there were modem connections that were 8-pin. Somewhere back in my fuzzy memory.

John H. Reinhardt

On 9/9/2023 4:45 PM, John H Reinhardt wrote:

I forgot the link to the plug, should anyone want some.

https://www.mouser.com/ProductDetail/806-KMDAX-7P

> On 9/7/2023 1:06 AM, Steven Schweda wrote:
>>> If needed, I cut off the old plug and splice it onto the new one.
>>> But nicer to find one with the right plug already.
>>
>>     The problem here is that the DEChub Work Group Units (such as the
>> DECSserver 90M) have two connectors for power: a two-row x 16-pin
>> male odd-ball, and a 7-pin female Mini-DIN.  The DEChub backplane uses
>> the 32-pin odd-ball; the individual-unit supply (which I don't recall
>> ever seeing) uses the Mini-DIN.
>>
>
> I got one (individual unit supply), an H7867 dual voltage 5/12v which came with the pile of DECservers and DECrepeaters mentioned below.  It's just a small, thin(ish) rectangular beige brick.
>
>>        https://manx-docs.org/collections/mds-199909/cd2/network/dehubom1.pdf
>>
>>     I'd expect that finding an adapter with either of these is unlikely,
>> at best.  What I use is a spliced-on cable with an 8-pin male Mini-DIN,
>> which seems to be close enough.  (The extra pin on the 8-pin male falls
>> neatly into the keyhole of the 7-pin female, contrary to the impression
>> given by the picture here:)
>>
>>        https://en.wikipedia.org/wiki/Mini-DIN_connector
>>
>
> By golly, you're right. I never noticed.  Here is a spec sheet for a series of Mini-DIN connectors and it clearly shows what you mean.
>
https://www.mouser.com/ProductDetail/806-KMDAX-7P

> https://www.mouser.com/datasheet/2/222/kyco_s_a0000255670_1-2271771.pdf
>
> Mouser has 1100+ of the 7-pin ones for $1.56 (quan:1, $1.42 quan:10). I just ordered a few as I have a small pile of DECserver 90M's I got on Ebay and they all need power.  Taking this connector and a 5vDC regulated wall wart is all they need. With the diagram on VCF it should be an easy job.
>
> https://forum.vcfed.org/index.php?threads/looking-for-decserver-mneng2-sys-mneng3-sys-and-mneng4-sys-boot-files.62810/#post-773655
>
>
>>     According to that article, PS2 mice used 6-pin connectors, so it's
>> more likely that I got my 8-pin stuff by bisecting some kind of
>> serial-modem cables.  It's been a while, so I don't remember what I
>> chopped up to get the 8-pin male Mini-DIN.
>>
>
> I think there were modem connections that were 8-pin.  Somewhere back in my fuzzy memory.
>
> John H. Reinhardt
>
>
>

> I got one (individual unit supply), an H7867 dual voltage 5/12v [...]

Just don't try to use it with a 5V-only Work Group Unit!

I've packaged most of what I've learned on this topic here:

http://antinode.info/dec/DECxxx90_Power.html

In my travels, I found fancier connector pictures (and other info)
here:

https://forum.vcfed.org/index.php?threads/x.62810/

I also noticed that the H7876-AA supply on my DEHUB-AX offers
5V @ 15A, +12V @ 1A, and -12V @ 0.1A. I haven't looked to see if the
DEHUB distributes the -12V. I haven't seen a Work Group Unit which
wants it, or a single-unit supply which offers it, but that proves
little.

One other note: As I recall, I've had a couple of cheap-Chinese
5V @ 2A adapters fail after a few years (driving DECserver 90M or 90TL).
Replacing the bad capacitors got tedious, so I've started buying
(cheap-Chinese) 4A models, which I hope will last longer.

> By golly, you're right. [...]

It happens from time to time.