Re: Replacement for Foam Filter for PDP 11/24

[Fritz Mueller via cctalk]

> On Sep 4, 2021, at 10:42 AM, Rob Jarratt via cctalk  
> wrote:
> Another query. The foam filter that sits in the front of my 11/24 CPU is
> clearly badly degraded and needs to be replaced. What do people replace this
> kind of stuff with? I guess it mustn't be too fine, this mesh seems quite
> coarse.

Hi Rob,

FWIW, I've used 3M Filtrete (‎FAPF-UCTF2PAMZ) for this application on an 11/34. 
 It seems I tighter weave than the old foam, but is designed for pretty high 
airflow and seems to work well.

It's about 1/8" thick, slightly compressible, easily cut to size w/ scissors, 
and adheres well to velcro hook tape.

   cheers,
 --FritzM.

Replacement for Foam Filter for PDP 11/24

[Rob Jarratt via cctalk]

Another query. The foam filter that sits in the front of my 11/24 CPU is
clearly badly degraded and needs to be replaced. What do people replace this
kind of stuff with? I guess it mustn't be too fine, this mesh seems quite
coarse.

 

https://rjarratt.files.wordpress.com/2021/09/1124-front-panel-2.jpg

 

Thanks

 

Rob

Re: VAX4000 VLC diagnostics/console

[Al Kossow via cctalk]

On 9/4/21 8:02 AM, Jay Jaeger via cctalk wrote:

Also, I see that version 1.0c of the open source  Blue Pill version has a fix that involves TERMPOWER: "Fixed issue with external power and 
TERMPOWER".


there is also a development discord for these little scsi adapters
https://discord.gg/kx2Kybx2mk

I was on it for a while, but it was too chatty for me to follow

Re: Capacitors on M8722 Board

[Jon Elson via cctalk]

On 9/4/21 4:34 AM, Rob Jarratt via cctalk wrote:

I have a PDP 11/24 which I hope to power up soon. The last time it had power
I noticed a bit of a burning smell which I failed to track down. However, I
did notice one capacitor on a memory board has a strange appearance, almost
as if there is some corrosion under the surface, it doesn't seem to be
bulging though, except along the top, but if it is bulging it is very bumpy.
I have a picture of it here:
https://rjarratt.files.wordpress.com/2021/09/wp_20210904_10_15_28_rich.jpg.
It is marked 47uF 30V, but it is also marked 20v as can be seen in the
picture.

  


Voltage is not critical, as long as it is above the supply 
on that bus.  But, that aluminum electrolytic cap certainly 
looks like it is ready to fail, possibly catastrophically.


Jon

Re: VAX4000 VLC diagnostics/console

[Zane Healy via cctalk]

> On Sep 4, 2021, at 6:34 AM, emanuel stiebler via cctalk 
>  wrote:
> 
> On 2021-09-04 08:30, Antonio Carlini via cctalk wrote:
> 
>> "Digital Diggings" couldn't get BlueSCSI to work on either VAX or Alpha:
>> https://www.youtube.com/watch?v=zFEh7owqHxU=36s.
>> That's a pity as it's much cheaper than SCSI2SD.
> 
> OK guys, but please compare that to costs for SCSI drives (please 6 of
> them, as you have partitions on the SDCARD), cost of SCSI controllers
> (QBUS/UNIBUS anyone?), or even IDE drives.
> 
> So this is whining on a pretty high level, and there is no noise, so you
> can keep your machines working. (and *** very easy backup too)
> 
> So, yes, there probably could be cheaper, but the guy spent a lot of
> time making it working.
> 
> In my opinion, it is worth every penny.
> 
> Cheers

I agree, it’s worth it.  I ended up buying 6 of them while on my Sabbatical, 
earlier this year, though I only had time to install two of them.  It means 
that my VAXstation 4000/VLC which was too noisy to use in the house is usable, 
and my VAXstation 4000/90 is almost silent.  I put one SCSI2SD in both of 
those.  I plan to put 2 in my DECnet Area router (a VAXstation 4000/60), and 2 
in one of my AlphaStations (probably an AlphaStation 200 4/233, since it only 
has Narrow SCSI).  

With the Area router, it will be replacing the disks in a BA350 shelf in my 
main rack, and just one board will offer a lot more space than the 2GB and 4GB 
drives I’m using.

I wish there was a U2W SCSI option for my Compaq XP1000/667 AlphaStation.  
There is a definite need for a replacement for faster drives, and systems that 
need a drive with an SCA interface (I’d also love one for my SGI O2’s).

Eventually I want to get it so I can run a BA23 or BA123 with a PDP-11, and a 
SCSI2SD board.  My main PDP-11/73 is a BA123 with removable SCSI HD’s (using 
the old PC trays from the late 90’s), and that lets me run all the OS’s I have 
installed.  A SCSI2SD would be a cleaner solution.

Is there any good solution for backing up an SD card from a SCSI2SD board?  I 
like how my emulated systems are backed up nightly as part of the backups setup 
for my VMware cluster.

Really I’m a huge fan of replacing floppies or HD’s with SD cards.  I did that 
YEARS ago with my C-64, and last year with my Amiga HW.  I look at it this way, 
what’s one of the key points of failure, disks.  This is especially true on 
floppy based systems.  For HD’s, it doesn’t even matter the age of the system.  
That’s why we have backups.

Zane

Re: VAX4000 VLC diagnostics/console

[Jay Jaeger via cctalk]

On 9/4/2021 5:44 AM, Adrian Graham wrote:



On 4 Sep 2021, at 02:42, Jay Jaeger via cctalk > wrote:


On 7/14/2021 12:32 PM, Adrian Graham via cctalk wrote:
VT100 to the rescue, the VLC is fine talking to it so now I'm 
wondering why
my old faithful hardware UART in this PC I'm typing on now has let me 
down.
The BlueSCSI appears as 7 devices though, which is usually a 
termination or

ID problem so I now need to dig out an external terminator for the box
since it's never had one. The hard drive in there has been good at
providing its own TERMPWR which the BlueSCSI should too but I'll play by
the rules to test things properly.
Cheers,


I think BlueSCSI will only appear as the devices you have image files 
named for on its SD card.


What I meant was on a SHO DEV I got 7 Quantum Fireballs (DKA0-500, 
DKA700), in my VAX days this meant there was either an ID conflict with 
another device on the bus or a termination issue. I only had one image 
on the sdcard which was ID0 so there weren’t any other devices present, 
so it had to be a termination issue.




Or a bug.

I don't think that these boards will *provide* terminator power, but I 
haven't looked at the schematics carefully.  If the VAX does provide 
terminator power, it might not be enough to both do that and power the 
blue pill.  I power mine from the 4 pin molex drive power connector by 
using a 4 pin molex to Berg connector adapter to match the connector on 
the one on the BlueSCSI board.


BTW, a caveat:  There is a "Black Pill" version from Tech By Androda out 
there.  The blue.scsi site that points to it indicates that BlueSCSI is 
open source (which it is), but THAT one, the one I bought from Tech By 
Androda IS NOT OPEN SOURCE.  He won't provide the code.  Not even 
binaries on his web site.  (There IS a warning about that on the page 
for the Black Pill (F4) version.)


Also, I see that version 1.0c of the open source  Blue Pill version has 
a fix that involves TERMPOWER: "Fixed issue with external power and 
TERMPOWER".


JRJ

Re: VAX4000 VLC diagnostics/console

[emanuel stiebler via cctalk]

On 2021-09-04 08:30, Antonio Carlini via cctalk wrote:

> "Digital Diggings" couldn't get BlueSCSI to work on either VAX or Alpha:
> https://www.youtube.com/watch?v=zFEh7owqHxU=36s.
> That's a pity as it's much cheaper than SCSI2SD.

OK guys, but please compare that to costs for SCSI drives (please 6 of
them, as you have partitions on the SDCARD), cost of SCSI controllers
(QBUS/UNIBUS anyone?), or even IDE drives.

So this is whining on a pretty high level, and there is no noise, so you
can keep your machines working. (and *** very easy backup too)

So, yes, there probably could be cheaper, but the guy spent a lot of
time making it working.

In my opinion, it is worth every penny.

Cheers

Anyone Have the H9642 Enclosure Maintenance Manual EK-187AA-MG

[Rob Jarratt via cctalk]

I have looked on Manx and on Bitsavers and I don't see it there.

 

Thanks

 

Rob

Re: VAX4000 VLC diagnostics/console

[Antonio Carlini via cctalk]

On 04/09/2021 02:42, Jay Jaeger via cctalk wrote:

On 7/14/2021 12:32 PM, Adrian Graham via cctalk wrote:
VT100 to the rescue, the VLC is fine talking to it so now I'm 
wondering why
my old faithful hardware UART in this PC I'm typing on now has let me 
down.


The BlueSCSI appears as 7 devices though, which is usually a 
termination or

ID problem so I now need to dig out an external terminator for the box
since it's never had one. The hard drive in there has been good at
providing its own TERMPWR which the BlueSCSI should too but I'll play by
the rules to test things properly.

Cheers,



I think BlueSCSI will only appear as the devices you have image files 
named for on its SD card.


JRJ


"Digital Diggings" couldn't get BlueSCSI to work on either VAX or Alpha: 
https://www.youtube.com/watch?v=zFEh7owqHxU=36s.



That's a pity as it's much cheaper than SCSI2SD.


Antonio


--
Antonio Carlini
anto...@acarlini.com

Re: VAX4000 VLC diagnostics/console

[Adrian Graham via cctalk]

> On 4 Sep 2021, at 02:42, Jay Jaeger via cctalk  wrote:
> 
> On 7/14/2021 12:32 PM, Adrian Graham via cctalk wrote:
>> VT100 to the rescue, the VLC is fine talking to it so now I'm wondering why
>> my old faithful hardware UART in this PC I'm typing on now has let me down.
>> The BlueSCSI appears as 7 devices though, which is usually a termination or
>> ID problem so I now need to dig out an external terminator for the box
>> since it's never had one. The hard drive in there has been good at
>> providing its own TERMPWR which the BlueSCSI should too but I'll play by
>> the rules to test things properly.
>> Cheers,
> 
> I think BlueSCSI will only appear as the devices you have image files named 
> for on its SD card.


What I meant was on a SHO DEV I got 7 Quantum Fireballs (DKA0-500, DKA700), in 
my VAX days this meant there was either an ID conflict with another device on 
the bus or a termination issue. I only had one image on the sdcard which was 
ID0 so there weren’t any other devices present, so it had to be a termination 
issue.

-- 
Adrian Graham
Owner of Binary Dinosaurs, the UK's biggest private home computer collection?
t: @binarydinosaursf: facebook.com/binarydinosaurs
w: www.binarydinosaurs.co.uk

Re: Capacitors on M8722 Board

[Tony Duell via cctalk]

On Sat, Sep 4, 2021 at 10:35 AM Rob Jarratt via cctalk
 wrote:

> I lifted it to measure its capacitance and ESR. It measures about 80uF and

With a lot of capacitance meters, a leaky capacitor will read high. So
that may explain why it's reading 80uF

> the ESR seems OK. I am unsure whether to replace it, and if so what voltage
> rating should I replace it with? I don't understand if this is a 30V rated
> capacitor or 20V. It seems that Unibus has some 20V signals, so I guess 20V
> might be right? I don't think 30V or 20V parts exist though, so I would need
> to get 35V or 25V. Maybe the voltage rating isn't too critical?

In general you can always replace a capacitor with one of a sensibly
higher voltage rating if there's space for it. It's the maximum
voltage that the capacitor will stand before it breaks down and passes
DC. In other words, a 35V or 63V one would be fine here.

-tony

Capacitors on M8722 Board

[Rob Jarratt via cctalk]

I have a PDP 11/24 which I hope to power up soon. The last time it had power
I noticed a bit of a burning smell which I failed to track down. However, I
did notice one capacitor on a memory board has a strange appearance, almost
as if there is some corrosion under the surface, it doesn't seem to be
bulging though, except along the top, but if it is bulging it is very bumpy.
I have a picture of it here:
https://rjarratt.files.wordpress.com/2021/09/wp_20210904_10_15_28_rich.jpg.
It is marked 47uF 30V, but it is also marked 20v as can be seen in the
picture.

 

I lifted it to measure its capacitance and ESR. It measures about 80uF and
the ESR seems OK. I am unsure whether to replace it, and if so what voltage
rating should I replace it with? I don't understand if this is a 30V rated
capacitor or 20V. It seems that Unibus has some 20V signals, so I guess 20V
might be right? I don't think 30V or 20V parts exist though, so I would need
to get 35V or 25V. Maybe the voltage rating isn't too critical?

 

Any advice?

 

Thanks

 

Rob