PDP 8a transformer capacitor replacement?

[Brian Walenz]

Having read all sorts of bad things about these older oil filled
capacitors, I decided to replace the one on my 8a.  I got what I think is a
replacement - 6 microF, 660VAC, 50/60Hz, "NO PCB's" - but it is physically
about 1/3 the size as the original.

Did the tech for these get that much better?

What purpose does this serve?  It's hanging off the transformer.  I see
lots of links about motor start capacitors, but nothing relating to
transformers.

http://www.mouser.com/ProductDetail/Cornell-Dubilier/SFA66S6K288B-F

Thanks,
b

Re: Testing bus transceivers

[Noel Chiappa]

> From: Guy Sotomayor

> A number of data books have circuits that were used to measure the
> parameters .. so you might want to look at some of them

Thanks for the tip! Alas, I don't know of any data books with circuits like
that - any pointers? (And it's only the leakage current I need to check; the
other 3 key DC parameters I have already managed to check.)


> From: Mark J. Blair

> Do you have any sort of precision, regulated, adjustable lab bench
> power supply that you could use to vary input voltage?

Well, I have some Lambdas, but I'm not sure they are 'precision' (any more -
the pots are kind of dirty/flaky, so they jump when you turn them).

> If not, using a potentiometer as you mentioned would also work.

Yeah, that's what I did - running a 500 ohm pot from ground to +5V provided a
nice input, and I was able to verify the 'maximum 0 input voltage' and the
'mininum 1 input voltage' quite easily.

I also realized that in a system with 'normal' single QBUS box with
termination, one has a 330 ohm pull-up in the CPU's termination, and 180 ohm
pull-up in the BDV11 terminator, which adds up to 42 mA into the transceiver
when pulling to low voltage; if one adds another 180 ohm pull-up, that adds
another 28 mA, getting me to the required 70 mA for the 'maximum 0 output
voltage' check.

Since the QBUS specs allow another termination, if you have a second box,
that's probably why they spec it at 70 mA, actually.


> Also, how many of these did you buy?

Umm, like 400? :-)

(Dave Bridgham and I are winding up to produce a QBUS card which uses SD
memory cards along with an FPGA and micro-controller to emulate a range of
DEC disk systems - RK11, RP11, etc - and we wanted to assure a goodly supply
of our selected transceiver chip before we spin out a PC board.)

> If it's something like a dozen, manual testing will be practical. If
> it's something like a hundred, then automating the testing might be a
> good idea, and a fun project all by itself if that sort of thing
> interests you.

Well, not really, to be honest (I'm not an analog person), plus to which I
have a zillion other projects (e.g. a bunch of UNIBUS machines to refurbish,
plus other non-computer things) which are backlogged, the last thing I need
is another one! ;-)

Also, you might be able to automate the _testing_, but one still has to plug
the chips in and out, which is a certain amount of work, so it's not like
automated testing would allow me to trivially check really large numbers of
chips. Which is why I've adopted the 'test randomly selected units for
meeting specs' approach (remember, I'm just trying to make sure these aren't
counterfeits), and for that, manual testing works fine.

Noel

Re: Could someone make this topic go away?

[Alexandre Souza]

   "delete" key does wonders...

---
Enviado do meu Apple IIGS (pq eu sou chique)
Meu site: http://www.tabalabs.com.br
Meu blog: http://tabajara-labs.blogspot.com




- Original Message - 
From: "Rick Bensene" 
To: "General Discussion: On-Topic and Off-Topic Posts" 


Sent: Wednesday, November 18, 2015 7:33 PM
Subject: Could someone make this topic go away?


I'm sick of this junk.  Let's get back to writing about real computers
rather than arguing over how the lists should work.

Sheesh.

-Rick 

Re: PDP 8a transformer capacitor replacement?

[Paul Berger]

On 2015-11-19 6:20 AM, Brian Walenz wrote:

Having read all sorts of bad things about these older oil filled
capacitors, I decided to replace the one on my 8a.  I got what I think is a
replacement - 6 microF, 660VAC, 50/60Hz, "NO PCB's" - but it is physically
about 1/3 the size as the original.

Did the tech for these get that much better?

What purpose does this serve?  It's hanging off the transformer.  I see
lots of links about motor start capacitors, but nothing relating to
transformers.

http://www.mouser.com/ProductDetail/Cornell-Dubilier/SFA66S6K288B-F

Thanks,
b
The capacitor is likely on a separate winding and the tank circuit 
created by this winding and the capacitor works to regulate the output 
voltage also referred to as a "Constant Voltage Transformer".  If this 
capacitor goes short you get zero output from the transformer a lesson I 
learned early in my career as a service rep.  When the capacitors are 
going bad they will sometimes swell up and even burst.  Early capacitors 
of this type where filled with an oil that contained PCBs but by the mid 
70s some manufacturers had replaced them with capacitors that did not 
contain PCBs on all in service machines.


Paul.

Re: PDP 8a transformer capacitor replacement?

[rod]

Hi

Power factor correction?
Hum suppression?

If its the type in a small squarish soldered up can.
Then open can and remove oil and paper.
Replace with  modern type
Close up can and re-solder
Put it back where it came from.

Rod


On 19/11/15 10:20, Brian Walenz wrote:

Having read all sorts of bad things about these older oil filled
capacitors, I decided to replace the one on my 8a.  I got what I think is a
replacement - 6 microF, 660VAC, 50/60Hz, "NO PCB's" - but it is physically
about 1/3 the size as the original.

Did the tech for these get that much better?

What purpose does this serve?  It's hanging off the transformer.  I see
lots of links about motor start capacitors, but nothing relating to
transformers.

http://www.mouser.com/ProductDetail/Cornell-Dubilier/SFA66S6K288B-F

Thanks,
b

Front Panels

[rod]

Hi Guys
 Well the panel is here and I'm analyzing it to see what it 
tells us.

So far it looks like I need to add a band of gray matte base to the front
and a band of similar over the light ports on on the back.

Looks like I have a new product. It's called an "Invisipanel"
Its a clear plexiglas blank I use for checking alignments.
Because its so clear I cant find it

Rod

Re: Could someone make this topic go away?

[Jason Scott]

As does pressing "m" (mute) if Gmail is your client. Archives the topic
automatically. Use it all the time.

On Thu, Nov 19, 2015 at 10:38 AM, Alexandre Souza <
alexandre.tabaj...@gmail.com> wrote:

>
>"delete" key does wonders...
>
> ---
> Enviado do meu Apple IIGS (pq eu sou chique)
> Meu site: http://www.tabalabs.com.br
> Meu blog: http://tabajara-labs.blogspot.com
>
>
>
>
> - Original Message - From: "Rick Bensene" 
> To: "General Discussion: On-Topic and Off-Topic Posts" <
> cctalk@classiccmp.org>
> Sent: Wednesday, November 18, 2015 7:33 PM
> Subject: Could someone make this topic go away?
>
>
>
> I'm sick of this junk.  Let's get back to writing about real computers
> rather than arguing over how the lists should work.
>
> Sheesh.
>
> -Rick
>

Re: Todays Topic from Panelman

[Jay Jaeger]

On 11/17/2015 2:03 PM, rod wrote:
> Thanks yes they do look similar. I'll download the data sheet.
> What I forgot to explain was the problem is not the switch itself but
> the additional part on top into which the two pivot pins locate.
> My policy is to produce form factor replacements. In this case the lever
> arm.
> If they can then be incorporated into other assemblies then good.
> 
> Here the lever rotates about a pivot point formed by the two sides of
> the additional structure on top.
> A missing segment in the lower semi-circular part of the lever engages
> with the slide switch and moves it.
> So there being no known source of the switch with the extra part on top
> and not wanting to change the lever.
> What do we do? It would not have been feasible to make the top part and
> attach it, as its spring steel.
> Its horrible stuff to work with. Pretty much you are limited to die
> stamping it in a heavy press.
> 

If the contacts are bad, then, after removal, perhaps you could unfold
the tabs that hold the fiber/phenolic piece with the contacts in it and
then swap that contact piece and maybe the switch post piece, and bend
the tabs back, keeping the original mechanical parts?

JRJ

> They would have punched the shape and the holes out with a hardened die
> and then before or after spot welding it to an empty switch body hit it
> again with a folding die to bring the sides up.
> That would be too expensive to get set up. So I am looking at alternatives.
> 
> Rod
> 
> 
> 
> 
> On 17/11/15 18:38, Jay Jaeger wrote:
>> On 11/17/2015 2:34 AM, rod wrote:
>>> Now to the slide switches themselves.
>>>
>>> They are mounted by the screw hole lugs having been slid into  a groove
>>> in two aluminum bars which in turn are attached to the PCB by pillars
>>> and screws.
>>> There are six connection pins on the bottom of each switch that go into
>>> holes in the PCB. (not all used) Switch replacement would be easy and a
>>> complete switch and lever sub module not too difficult. I hear a voice
>>> from the distant past saying 'Micro switches'
>>>
>>> Thats all for to-day
>>>
>>> Rod
>>>
>> The ones I have seen (on my PDP-8/L and PDP-12) are simple stock
>> old-school slide switches (definitely not Micro-Switch switches), that
>> typically look like this one:
>>
>> http://www.digikey.com/product-detail/en/GF-1126-1110/SW105-ND/948
>>
>> (I did *not* check dimensions to see if this particular one is right or
>> not - there were standard size and miniature versions.  But the photo
>> looks about right).
>>
>> JRU
>>
>>
> 
> 

VAX 4000-200 Maintenance

[william degnan]

Performed maintenance of my VAX 4000-200.

Removed NiCad battery
Replaced hard drive
Made new image of system drive

The how-to is all over the web, but I summarized a lot of the basic support
tasks associated with a networked VAX 4000 here for anyone interested in a
simple "for dummies" page

http://vintagecomputer.net/browse_thread.cfm?id=608

The system is hosted here:
vax4000.vintagecomputer.net

-- 
Bill

Re: VAX 4000-200 Maintenance

[william degnan]

On Thu, Nov 19, 2015 at 4:27 PM, Robert Jarratt  wrote:

> > -Original Message-
> > From: cctech [mailto:cctech-boun...@classiccmp.org] On Behalf Of william
> > degnan
> > Sent: 19 November 2015 17:28
> > To: cctech
> > Subject: VAX 4000-200 Maintenance
> >
> > Performed maintenance of my VAX 4000-200.
> >
> > Removed NiCad battery
>
>
> My to-do list has me doing the rounds of all my machines to check them all
> for the batteries. I'd like to replace rather than remove though, but that
> could get expensive at about £10-12 pounds per machine for the cordless
> phone battery packs sold by Maplin. Maybe there is a better alternative, I
> should go and take a look.
>
> Regards
>
> Rob
>
>
>
It was a pain to take the M7626 apart, I did think about replacing but
decided I don't mind entering in the date whenever I boot up the system vs.
worrying about the future.

Overall I remove all batteries unless they're required.  For example I
removed all Amiga 2000 batteries, but keep up-to-date with things like IBM
5170 AT's and Compaq's 386-Pentium class systems because they need
batteries to hold their configuration, (what a pain).


-- 
Bill

RE: VAX 4000-200 Maintenance

[Robert Jarratt]

> -Original Message-
> From: cctech [mailto:cctech-boun...@classiccmp.org] On Behalf Of william
> degnan
> Sent: 19 November 2015 17:28
> To: cctech
> Subject: VAX 4000-200 Maintenance
> 
> Performed maintenance of my VAX 4000-200.
> 
> Removed NiCad battery


My to-do list has me doing the rounds of all my machines to check them all for 
the batteries. I'd like to replace rather than remove though, but that could 
get expensive at about £10-12 pounds per machine for the cordless phone battery 
packs sold by Maplin. Maybe there is a better alternative, I should go and take 
a look.

Regards

Rob

> Replaced hard drive
> Made new image of system drive
> 
> The how-to is all over the web, but I summarized a lot of the basic support 
> tasks
> associated with a networked VAX 4000 here for anyone interested in a simple
> "for dummies" page
> 
> http://vintagecomputer.net/browse_thread.cfm?id=608
> 
> The system is hosted here:
> vax4000.vintagecomputer.net
> 
> --
> Bill

Re: VAX 4000-200 Maintenance

[Sue Skonetski]

Dear Rob,

Just an idea Nemonix Engineering (previous employer) does maintenance and 
support for PDP, VAX and Alpha.  I know that they had new batteries.  Not new 
in the DEC packaging but newly mad they may be able to do some thing for you.

Contact Wayne Beeson and let him know I sent you.  

url is nemonix.com 
phone is 508-393-7700

Coming from a DEC background it was amazing to see this hardware still in 
active work.  On of my favorites was discussions was around fans.  When the 
hardware was originally made they did not include sealed fans for general sale 
so as the fan got old and slowed down it would gradually heat up the mother 
board so folks thought it was a mother board issue, get it replaced and then a 
few moths later the fan would break and people would have t replace.  Nemonix 
did both so it was not an issue just uncomfortable for the customer.

If there is anything I can do to help please just let me know.

Warm Regards,
Sue



> On Nov 19, 2015, at 4:27 PM, Robert Jarratt  
> wrote:
> 
>> -Original Message-
>> From: cctech [mailto:cctech-boun...@classiccmp.org] On Behalf Of william
>> degnan
>> Sent: 19 November 2015 17:28
>> To: cctech
>> Subject: VAX 4000-200 Maintenance
>> 
>> Performed maintenance of my VAX 4000-200.
>> 
>> Removed NiCad battery
> 
> 
> My to-do list has me doing the rounds of all my machines to check them all 
> for the batteries. I'd like to replace rather than remove though, but that 
> could get expensive at about £10-12 pounds per machine for the cordless phone 
> battery packs sold by Maplin. Maybe there is a better alternative, I should 
> go and take a look.
> 
> Regards
> 
> Rob
> 
>> Replaced hard drive
>> Made new image of system drive
>> 
>> The how-to is all over the web, but I summarized a lot of the basic support 
>> tasks
>> associated with a networked VAX 4000 here for anyone interested in a simple
>> "for dummies" page
>> 
>> http://vintagecomputer.net/browse_thread.cfm?id=608
>> 
>> The system is hosted here:
>> vax4000.vintagecomputer.net
>> 
>> --
>> Bill
> 

Sue Skonetski

VP of Customer Advocacy
sue.skonet...@vmssoftware.com
Office: +1 (978) 451-0116
Mobile: +1 (603) 494-9886







Mit freundlichen Grüßen – Avec mes meilleures salutations

Re: VAX 4000-200 Maintenance

[Glen Slick]

On Thu, Nov 19, 2015 at 1:35 PM, william degnan  wrote:
> It was a pain to take the M7626 apart, I did think about replacing but
> decided I don't mind entering in the date whenever I boot up the system vs.
> worrying about the future.
>

Removing 6 screws and a lock nut on the M7626 KA660 H3602 console
panel to remove the PCB so you can remove the battery now is a lot
easier and better than doing it later after the battery has started
leaking and corroding things and then trying to repair the damage.

I was just looking at a system with an M7626 KA660 a couple of days
ago and the network connectivity through the H3602 AUI Ethernet port
was very flaky. The H3602 had some signs of leaking battery corrosion
that I had previously tried to clean. I swapped that H3602 panel with
another one that also had some signs of leaking battery corrosion and
that one seemed to work OK, at least for now. Trying to correct
whatever is damaged on the bad H3602 panel will be a pain. It's not
worth the risk of leaving those NiCad battery packs in any old DEC
gear. It's not that much of a pain to set the date and time every time
I actually get around to powering on the systems.

The early VAX 3100 desktops have those same evil NiCad battery packs.

Re: VAX 4000-200 Maintenance

[Mike Stein]

- Original Message - 
From: "Robert Jarratt" 

Sent: Thursday, November 19, 2015 4:27 PM

...
My to-do list has me doing the rounds of all my machines to check them all for
the batteries. I'd like to replace rather than remove though, but that could get
expensive at about £10-12 pounds per machine for the cordless phone battery
packs sold by Maplin. Maybe there is a better alternative, I should go and take
a look.

Regards

Rob

- Reply -

Wow! I buy mine for $2 to $4 at the local 'Dollar' store...

Or you could order from the usual place; e.g.:
http://www.aliexpress.com/store/group/Battery/1191734_259040387.html

m

Re: Could someone make this topic go away?

[Eric Christopherson]

On Thu, Nov 19, 2015, Jason Scott wrote:
> As does pressing "m" (mute) if Gmail is your client. Archives the topic
> automatically. Use it all the time.

That doesn't work for me; perhaps it's because all mail from this list
is already (automatically) archived by a rule I have. I have tons of
rules like that; they apply an appropriate tag and archive the messages,
so I have to navigate into a specific folder to read a group's messages.

-- 
Eric Christopherson

Replacing MicroVAX II PSU With a Modern PSU

[Robert Jarratt]

While I look into what is wrong with my H7864, I'd like to use a modern PSU
to power my machine (actually an rtVAX 1000).

 

I think I would need to deal with the following problems:

 

1.   Finding the right connectors (ideally, I am sure I could rig up
something more temporary).

2.   A way to power the fans, which I believe are 15V, perhaps they
would run on 12V as I wouldn't run the machine for long periods anyway, or I
could just use PC fans.

3.   Emulate the DC OK and P OK signals, I suspect these would be simple
+5V signals which could perhaps just come from the +5V of the PSU anyway
(unless there is a problem with that).

4.   The most difficult bit, I suspect, would be the PSU LTC signal ,
which I believe is some kind of clock. I don't know what the spec of the
signal is, but I will get a scope on a working one to see (NB don't want to
risk a working PSU on this machine in case it was a problem with the machine
itself that caused the first PSU to fail, I don't mind sacrificing a modern
PSU if need be).

 

Has anyone done this before?

 

Regards

 

Rob

Re: VAX 4000-200 Maintenance

[Alexandre Souza]

Common househoud vinegar does wonders for this kind of battery leak
problem...

2015-11-19 20:11 GMT-02:00 Glen Slick :

> On Thu, Nov 19, 2015 at 1:35 PM, william degnan 
> wrote:
> > It was a pain to take the M7626 apart, I did think about replacing but
> > decided I don't mind entering in the date whenever I boot up the system
> vs.
> > worrying about the future.
> >
>
> Removing 6 screws and a lock nut on the M7626 KA660 H3602 console
> panel to remove the PCB so you can remove the battery now is a lot
> easier and better than doing it later after the battery has started
> leaking and corroding things and then trying to repair the damage.
>
> I was just looking at a system with an M7626 KA660 a couple of days
> ago and the network connectivity through the H3602 AUI Ethernet port
> was very flaky. The H3602 had some signs of leaking battery corrosion
> that I had previously tried to clean. I swapped that H3602 panel with
> another one that also had some signs of leaking battery corrosion and
> that one seemed to work OK, at least for now. Trying to correct
> whatever is damaged on the bad H3602 panel will be a pain. It's not
> worth the risk of leaving those NiCad battery packs in any old DEC
> gear. It's not that much of a pain to set the date and time every time
> I actually get around to powering on the systems.
>
> The early VAX 3100 desktops have those same evil NiCad battery packs.
>

Re: Could someone make this topic go away?

[ethan]

That doesn't work for me; perhaps it's because all mail from this list
is already (automatically) archived by a rule I have. I have tons of
rules like that; they apply an appropriate tag and archive the messages,
so I have to navigate into a specific folder to read a group's messages.


Am I the only one left using Pine!?

I get odd looks when I'm checking email from my cell phone.

DEC 4260 transistors (MOS clock driver on LSI-11 CPU)

[Eric Smith]

Does anyone happen to know what the industry-standard equivalent for a
DEC 4260 PNP transistors in the MOS clock driver circuitry on LSI-11
CPU is?  Is it a 2N4260?

Thanks!
Eric

RE: VAX 4000-200 Maintenance

[Robert Jarratt]

Thanks for the suggestion. This is of course entirely for hobbyist purposes, I 
will look for alternatives here in the UK, but if that fails I will give it a 
go.

Regards

Rob

> -Original Message-
> From: cctech [mailto:cctech-boun...@classiccmp.org] On Behalf Of Sue
> Skonetski
> Sent: 19 November 2015 22:12
> To: General Discussion: On-Topic Posts
> Subject: Re: VAX 4000-200 Maintenance
> 
> Dear Rob,
> 
> Just an idea Nemonix Engineering (previous employer) does maintenance and
> support for PDP, VAX and Alpha.  I know that they had new batteries.  Not new
> in the DEC packaging but newly mad they may be able to do some thing for
> you.
> 
> Contact Wayne Beeson and let him know I sent you.
> 
> url is nemonix.com  phone is 508-393-7700
> 
> Coming from a DEC background it was amazing to see this hardware still in
> active work.  On of my favorites was discussions was around fans.  When the
> hardware was originally made they did not include sealed fans for general sale
> so as the fan got old and slowed down it would gradually heat up the mother
> board so folks thought it was a mother board issue, get it replaced and then a
> few moths later the fan would break and people would have t replace.
> Nemonix did both so it was not an issue just uncomfortable for the customer.
> 
> If there is anything I can do to help please just let me know.
> 
> Warm Regards,
> Sue
> 
> 
> 
> > On Nov 19, 2015, at 4:27 PM, Robert Jarratt 
> wrote:
> >
> >> -Original Message-
> >> From: cctech [mailto:cctech-boun...@classiccmp.org] On Behalf Of
> >> william degnan
> >> Sent: 19 November 2015 17:28
> >> To: cctech
> >> Subject: VAX 4000-200 Maintenance
> >>
> >> Performed maintenance of my VAX 4000-200.
> >>
> >> Removed NiCad battery
> >
> >
> > My to-do list has me doing the rounds of all my machines to check them all
> for the batteries. I'd like to replace rather than remove though, but that 
> could
> get expensive at about £10-12 pounds per machine for the cordless phone
> battery packs sold by Maplin. Maybe there is a better alternative, I should go
> and take a look.
> >
> > Regards
> >
> > Rob
> >
> >> Replaced hard drive
> >> Made new image of system drive
> >>
> >> The how-to is all over the web, but I summarized a lot of the basic
> >> support tasks associated with a networked VAX 4000 here for anyone
> >> interested in a simple "for dummies" page
> >>
> >> http://vintagecomputer.net/browse_thread.cfm?id=608
> >>
> >> The system is hosted here:
> >> vax4000.vintagecomputer.net
> >>
> >> --
> >> Bill
> >
> 
> Sue Skonetski
> 
> VP of Customer Advocacy
> sue.skonet...@vmssoftware.com
> Office: +1 (978) 451-0116
> Mobile: +1 (603) 494-9886
> 
> 
> 
> 
> 
> 
> 
> Mit freundlichen Grüßen – Avec mes meilleures salutations
> 

RE: VAX 4000-200 Maintenance

[Robert Jarratt]

> -Original Message-
> From: cctech [mailto:cctech-boun...@classiccmp.org] On Behalf Of Mike
Stein
> Sent: 19 November 2015 22:54
> To: General Discussion: On-Topic Posts
> Subject: Re: VAX 4000-200 Maintenance
> 
> - Original Message -
> From: "Robert Jarratt" 
> Sent: Thursday, November 19, 2015 4:27 PM
> 
> ...
> My to-do list has me doing the rounds of all my machines to check them all
for
> the batteries. I'd like to replace rather than remove though, but that
could get
> expensive at about £10-12 pounds per machine for the cordless phone
battery
> packs sold by Maplin. Maybe there is a better alternative, I should go and
take
> a look.
> 
> Regards
> 
> Rob
> 
> - Reply -
> 
> Wow! I buy mine for $2 to $4 at the local 'Dollar' store...
> 
> Or you could order from the usual place; e.g.:
> http://www.aliexpress.com/store/group/Battery/1191734_259040387.html
> 


Well, I am in the UK, but I do think I should try to find a cheaper source,
I am sure it will exist, I have just been too lazy up to now.

Regards

Rob

[cctalk] Re: Could someone make the list do the [cctalk] thing in the subject line?

[Jerry Kemp]

Been AFK and out of town for a week and just catching up on all my email 
messages.

I'm on a couple of emailing list where the modified subject header is an issue 
of contention.  Not sure why, but the square bracket header thing sure helps me. 
 Everyone else just does this by default.


My work around is have procmail add the [square] bracket entry to the header 
when the email come in.


Here is a sample procmail recipe from another mailing list.

..

# IPv6 operators forum header
:0 fw
* ^List-Id:[ ].*\
|/bin/sed -e 's/^Subject:[ ]*/Subject: [IPv6 operators forum] /'

..


This works great for me.


YMMV.  enjoy,

Jerry





On 11/17/15 09:54 AM, et...@757.org wrote:

Hello,

   By any chance could someone configure the mailing list to add [cctalk] or
[cc] or [cct] into the beginning of the subject line? Not looking to filter,
just not looking to delete messages.


--
Ethan O'Toole