As some of you may be aware I am trying to find a fault in a Rainbow H7842
PSU. I am using Tony Duell's schematic from here
http://www.bitsavers.org/pdf/dec/rainbow/duell_schematics/psu.pdf.
I have been testing the Control Module by using a bench PSU to supply 15VDC
to the input of the 7812 regulator (p2, PSU Sheet 1).
My diagnosis shows that the control module is shutting down the PWM (p6,
Control Module Sheet 2) because it is detecting an overcurrent in the -12V
side (E3d on Control Module sheet 1, although I have determined that it is
actually E3c).
This seems to be because I measure a steady 0.6V on pin 6 of the transformer
(p4, PSU Sheet 3). I just can't imagine where it might be coming from as the
chopper won't be running. I had previously removed the transformer and there
are no shorts between the pin 5-pin 6 winding and any of the other pins on
the transformer. I checked all the DC outputs of the PSU when powering the
7812 from the bench, both on a working PSU and the non-working one. They are
all at zero except the -12V output on the non-working PSU, which is +0.6V.
But the voltage can't come out of nowhere.
I am stumped and would appreciate any suggestions.
Thanks
Rob
This is on Discord.
I have an HP 2100A with a paper tape punch (a HP labelled Facit), tape
punch (HP), and an 7900A disc. The thing is in decent shape - full of
cards. The keyswitch is out of the thing, but I am pretty sure I still
have it.
Right now, I have me hands on the 2100A and Facit paper tape punch
(with bracket) - can I get $1000 for this combo? When I get my hands
on the reader and 7900A ( I think they are just buried!), we can deal
with them later, as I do not like to sell what my hands are not on.
Located around Kingston NY.
Oh, I have a 5 foot rack for this thing, still back at the old house.
--
Will
>> DSM-IV is "Diagnostic and Statistical Manual" for mental disorders,
>> and is
On Wed, 28 Jun 2023, Ali wrote:
> Fred,
> You are showing your age ;). The DSM-V has been out for a while now and the
> first revision (DSM V-TR TR=Text Revision, gotta love the Psych guys...) is
> coming out (is out?) soon
My age is getting quite difficult to hide.
The "new" (now 10? years old) edition (DSM-V) is not without controversy,
such as grief/depression; there are actually some who still prefer to use
the DSM-IV. When we put the DSM-V on the shelf in Reference, we had some
patrons asking us to bring back the DSM-IV.
But yes, my joke should probably have been worded DSM-V
Anyone in MD got an AUI cable (few feet long) I can steal so I don't
have to remove the bolts from the Pro/380's Ethernet socket or the pins
on my 10bt ethernet MAU?
Friendly note: If you try to boot a Pro/380 running POS 3.2 with Decnet
installed and don't have the loopback plug the system will crash hard
with a numeric error on the display. Noted.
CZ
Anyone in MD got an AUI cable (few feet long) I can steal so I don't
have to remove the bolts from the Pro/380's Ethernet socket or the pins
on my 10bt ethernet MAU?
Friendly note: If you try to boot a Pro/380 running POS 3.2 with Decnet
installed and don't have the loopback plug the system will crash hard
with a numeric error on the display. Noted.
CZ
Hey folks,
Now that I'm done moving house I have time to wrench on the 6150.
Before moving it worked; you'd power it on, the LCD status countdown
would get to an OK value, but the CRT wasn't legible. I figured I'd be
wrenching on the CRT.
Instead, now when I power it on, it powers on for a second or two and
then shuts off. I'm assuming this indicates a short or power-draw
somewhere. I've reseated the CPU and RAM cards, the peripherals, and
unplugged the hard drives (2x ESDI) and floppy in case they had a
fault that was drawing too many amps and causing the power supply to
shut-down. I noticed nothing on the CPU or RAM boards (exploded caps,
etc.)
What should I look at next?
--
-Jon
+44 7792 149029
Hi!
As I'm preparing to setup my old hardware, I fetched two VAXstations
(4000/90 and /96) from storage and cleaned one of them throughoutly.
Then I gave power (to both of them), but both won't really start:
all 8 diag LEDs are on (--> power available but CPU didn't start
executing instructions.)
I took the PSU (from the cleaned /90), a DEC H7819-AA, and measured
it. Unfortunately I didn't find pinouts or schematics at a first
search. The plate states that there should be 3.3V, 5V, 12V, -12V and
-9V. I found most of that:
+------------------------------------------------------------------+
| o |
| DEC H7819-AA PSU 10 +---+ 1 |
| (view at the bottom side) | | |
| | | |
| | | |
| 18 +---+ 9 |
| o |
| +-------+ +-------+ |
| | Fan | | Fan | |
+----------------+-------+----+-------+----------------------------+
With above pin numbering, this is what I could find / measure / deduce:
3V3 brown 10 1 blue 12V
3V3 brown 11 2 black GND
GND black 12 3 red 5V
GND black 13 4 red 5V
GND black 14 5 black GND
5V red 15 6 black GND
5V red 16 7 white -12V
5V red 17 8 blue (0.78V)
(4.91V) lilac 18 9 brown (-1.65V)
Most values look plausible, except those three in parentheses. At
least one of them should probably be -9V wrt. GND I guess, but that's
totally absent. And what's the other two? (If I got the colors wrong:
Please forgive, I'm red-green blind.) That could be some "power-okay"
indicator, or external switch-off?
Maybe anybody has faced these issues and can point me to some docs
or "well known to be failing" capacitors? I'd be quite grateful for
any hints! :) ...and hope that maybe the above drawing/measurements
will be helpful for anybody else later on.
Thanks,
Jan-Benedict
--
OK. I have just read in a bunch of Rainbow disks. Most of them read fine on
the first, second or third try. Some have a sector or three amiss (I've not
yet checked to see if those sectors are mapped to the filesystem or not).
Some appear to be 'unformatted' though sometimes they read with errors.
These disks have what appears to be some kind of grime/mold/??? on their
surface.
Is there a good way to read these diskettes? To clean the grime off and
allow the floppy to spin (they all are super loud)...
At the rate things are going, there will be 5-10 of these...
Warner
Hello,
I have a number of DC1000 tape cartridges, with and without relevant data on them.
I have 2 questions:
1. Has anybody the IRWIN TFORMAT software?
2. I want to make images from the cartridges.
Has anybody done this?
We tried with Linux Mint, but the drive is unknown.
Thanks in advance
Lothar
Does anyone have one of Dwight Elvey's KIM-1 diagnostics boards out there who
would be willing to let me borrow it (I'm in southern California)? I would be
happy to pay shipping and a rental cost, provide a deposit, etc. Please contact
me off list if you're willing and the arrangements you'd prefer.
Yes, I'm aware schematics exist, but I was hoping not to place my ability to
fix this unit entirely upon my ability to assemble a board if a working one is
already out there.
--
------------------------------------ personal: http://www.cameronkaiser.com/ --
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser(a)floodgap.com
-- I went to San Francisco. I found someone's heart. Now what? ----------------
