20 Nov
2014
20 Nov
'14
12:31 p.m.
Hey all,
I've been getting the bug worse and worse to start working on a real
pdp11. The Raspberry Pi / simh emulation is fantastic, but my hunger for
authenticity is becoming rampant. I haven't run the youngest in my fleet
of pdp11s, the 11/73, since circa 2002 and if I recall correctly, it was
becoming flaky and popping out to ODT inexplicably from time to time back
then (I think this is the one with the notoriously combustible power supply
wires that probably haven't been ECO'd yet -- need to get to that too).
It's been lying in a warehouse in western Pennsylvania with no heat and a
lot of dust. So, worst case, we're talking temperature transients around
110 F and -20 F with no protection. It did stay quite dry.
Think it'd be bad to simply blow the dust off and fire it up?
thx
jake
20 Nov
20 Nov
12:54 p.m.
On Nov 20, 2014, at 2:31 PM, Jacob Ritorto
<jacob.ritorto at gmail.com> wrote:
Hey all,
I've been getting the bug worse and worse to start working on a real
pdp11. The Raspberry Pi / simh emulation is fantastic, but my hunger for
authenticity is becoming rampant. I haven't run the youngest in my fleet
of pdp11s, the 11/73, since circa 2002 and if I recall correctly, it was
becoming flaky and popping out to ODT inexplicably from time to time back
then (I think this is the one with the notoriously combustible power supply
wires that probably haven't been ECO'd yet -- need to get to that too).
It's been lying in a warehouse in western Pennsylvania with no heat and a
lot of dust. So, worst case, we're talking temperature transients around
110 F and -20 F with no protection. It did stay quite dry.
Think it'd be bad to simply blow the dust off and fire it up?
There has been a lot of talk about reforming capacitors lately. I do not subscribe to it,
mostly because the electronics guru I know (Gary Gough) doesn't.
I would remove all the boards, blow it out, insert the minimum board set, (CPU, memory, DL
console, maybe bus terminator depending on backplane) and just turn it on.
Your mileage may vary...
thx
jake
12:55 p.m.
At the very least, take a good long look at the power supply and its caps.
Has the storage, as bad as it's been, been dry? If not, you'll almost
certainly have corrosion all over the place, especially in the fastons ISTR
run power to the backplane. (I haven't looked at my own 11/73 in a few
years, but it's in a dry, temperature-stable basement.)
Best of luck! - Ian
On Nov 20, 2014 12:32 PM, "Jacob Ritorto" <jacob.ritorto at gmail.com>
wrote:
Hey all,
I've been getting the bug worse and worse to start working on a real
pdp11. The Raspberry Pi / simh emulation is fantastic, but my hunger for
authenticity is becoming rampant. I haven't run the youngest in my fleet
of pdp11s, the 11/73, since circa 2002 and if I recall correctly, it was
becoming flaky and popping out to ODT inexplicably from time to time back
then (I think this is the one with the notoriously combustible power supply
wires that probably haven't been ECO'd yet -- need to get to that too).
It's been lying in a warehouse in western Pennsylvania with no heat and a
lot of dust. So, worst case, we're talking temperature transients around
110 F and -20 F with no protection. It did stay quite dry.
Think it'd be bad to simply blow the dust off and fire it up?
thx
jake
1:34 p.m.
Good deal. I guess I'm just gonna go for it after a cursory inspection and
dusting. It has stayed utterly dry; just the temp and dust were concerns.
I'll report back in a while.. Thanks!
On Thu, Nov 20, 2014 at 3:55 PM, Ian S. King <isking at uw.edu> wrote:
At the very least, take a good long look at the power
supply and its caps.
Has the storage, as bad as it's been, been dry? If not, you'll almost
certainly have corrosion all over the place, especially in the fastons ISTR
run power to the backplane. (I haven't looked at my own 11/73 in a few
years, but it's in a dry, temperature-stable basement.)
Best of luck! - Ian
On Nov 20, 2014 12:32 PM, "Jacob Ritorto" <jacob.ritorto at gmail.com>
wrote:
Hey all,
I've been getting the bug worse and worse to start working on a real
pdp11. The Raspberry Pi / simh emulation is fantastic, but my hunger for
authenticity is becoming rampant. I haven't run the youngest in my fleet
of pdp11s, the 11/73, since circa 2002 and if I recall correctly, it was
becoming flaky and popping out to ODT inexplicably from time to time back
then (I think this is the one with the notoriously combustible power
supply
wires that probably haven't been ECO'd
yet -- need to get to that too).
It's been lying in a warehouse in western Pennsylvania with no heat and a
lot of dust. So, worst case, we're talking temperature transients around
110 F and -20 F with no protection. It did stay quite dry.
Think it'd be bad to simply blow the dust off and fire it up?
thx
jake
3:26 p.m.
Perfect example of only listening to
what one wants to hear.
On 11/20/2014 4:34 PM, Jacob Ritorto wrote:
Good deal. I guess I'm just gonna go for it after
a cursory inspection and
dusting. It has stayed utterly dry; just the temp and dust were concerns.
I'll report back in a while.. Thanks!
On Thu, Nov 20, 2014 at 3:55 PM, Ian S. King<isking at uw.edu> wrote:
At the very least, take a good long look at the
power supply and its caps.
Has the storage, as bad as it's been, been dry? If not, you'll almost
certainly have corrosion all over the place, especially in the fastons ISTR
run power to the backplane. (I haven't looked at my own 11/73 in a few
years, but it's in a dry, temperature-stable basement.)
Best of luck! - Ian
On Nov 20, 2014 12:32 PM, "Jacob Ritorto"<jacob.ritorto at gmail.com>
wrote:
Hey all,
I've been getting the bug worse and worse to start working on a real
pdp11. The Raspberry Pi / simh emulation is fantastic, but my hunger for
authenticity is becoming rampant. I haven't run the youngest in my fleet
of pdp11s, the 11/73, since circa 2002 and if I recall correctly, it was
becoming flaky and popping out to ODT inexplicably from time to time back
then (I think this is the one with the notoriously combustible power
supply
> wires that probably haven't been ECO'd yet -- need to get to that too).
> It's been lying in a warehouse in western Pennsylvania with no heat and a
> lot of dust. So, worst case, we're talking temperature transients around
> 110 F and -20 F with no protection. It did stay quite dry.
>
> Think it'd be bad to simply blow the dust off and fire it up?
>
> thx
> jake
>
9:46 p.m.
Well, things inside were clean and pretty minimally configured, so, with
all apologies, I jumped the gun and applied power, but I'm afraid the old
girl just didn't survive the twelve years of temperature transients.
The illuminated ba23 power rocker switch lights up, but that's absolutely
it. No fans, no familiar power supply squeal, no drive spinup, nothing on
the seven-segment CPU state display on the rear. Seems thoroughly dead.
I guess I need to start tearing it down and debugging the power supply as
I recall that it was at least doing more than this before the years of bad
storage.
So I need to find power supply diagrams and start tracing things out,
right? Any ideas as to where to begin?
On Thu, Nov 20, 2014 at 4:34 PM, Jacob Ritorto <jacob.ritorto at gmail.com>
wrote:
Good deal. I guess I'm just gonna go for it after
a cursory inspection
and dusting. It has stayed utterly dry; just the temp and dust were
concerns. I'll report back in a while.. Thanks!
On Thu, Nov 20, 2014 at 3:55 PM, Ian S. King <isking at uw.edu> wrote:
At the very least, take a good long look at the
power supply and its caps.
Has the storage, as bad as it's been, been dry? If not, you'll almost
certainly have corrosion all over the place, especially in the fastons
ISTR
run power to the backplane. (I haven't looked at my own 11/73 in a few
years, but it's in a dry, temperature-stable basement.)
Best of luck! - Ian
On Nov 20, 2014 12:32 PM, "Jacob Ritorto" <jacob.ritorto at gmail.com>
wrote:
Hey all,
I've been getting the bug worse and worse to start working on a real
pdp11. The Raspberry Pi / simh emulation is fantastic, but my hunger
for
authenticity is becoming rampant. I haven't
run the youngest in my
fleet
of pdp11s, the 11/73, since circa 2002 and if I
recall correctly, it was
becoming flaky and popping out to ODT inexplicably from time to time
back
then (I think this is the one with the
notoriously combustible power
supply
wires that probably haven't been ECO'd
yet -- need to get to that too).
It's been lying in a warehouse in western Pennsylvania with no heat and
a
lot of dust. So, worst case, we're talking
temperature transients
around
110 F and -20 F with no protection. It did stay
quite dry.
Think it'd be bad to simply blow the dust off and fire it up?
thx
jake
11:33 p.m.
There is no printset that I am aware of the for the H7864 PSU. I have a dead one of these
too, I do know which component failed but I don't know *why* it failed. As part of
that diagnosis I have made a partial schematic of a couple of parts of the boards.
The schematic for the Primary Control Module is here: http://1drv.ms/1yBzYTN (png) or
here: http://1drv.ms/1xFXUnR (Eagle schematic). I may not have drawn it logically, and may
have some bits wrong, as it is quite difficult to derive the schematic and it is easy to
make mistakes. I don?t know how to identify zener diodes, so all diodes are drawn as
ordinary ones. I was also unable to draw the transformers correctly as I don't know
their spec and pinout.
Regards
Rob
-----Original Message-----
From: cctech [mailto:cctech-bounces at classiccmp.org] On Behalf Of Jacob
Ritorto
Sent: 21 November 2014 05:46
To: General Discussion: On-Topic Posts
Subject: Re: 11/73 (ba23) bringup after 12 years in deplorable storage
conditions
Well, things inside were clean and pretty minimally configured, so, with all
apologies, I jumped the gun and applied power, but I'm afraid the old girl just
didn't survive the twelve years of temperature transients.
The illuminated ba23 power rocker switch lights up, but that's absolutely it.
No fans, no familiar power supply squeal, no drive spinup, nothing on the
seven-segment CPU state display on the rear. Seems thoroughly dead.
I guess I need to start tearing it down and debugging the power supply as I
recall that it was at least doing more than this before the years of bad storage.
So I need to find power supply diagrams and start tracing things out, right?
Any ideas as to where to begin?
On Thu, Nov 20, 2014 at 4:34 PM, Jacob Ritorto <jacob.ritorto at gmail.com>
wrote:
> Good deal. I guess I'm just gonna go for it after a cursory
> inspection and dusting. It has stayed utterly dry; just the temp and
> dust were concerns. I'll report back in a while.. Thanks!
>
> On Thu, Nov 20, 2014 at 3:55 PM, Ian S. King <isking at uw.edu> wrote:
>
>> At the very least, take a good long look at the power supply and its caps.
>>
>> Has the storage, as bad as it's been, been dry? If not, you'll
>> almost certainly have corrosion all over the place, especially in the
>> fastons ISTR run power to the backplane. (I haven't looked at my own
>> 11/73 in a few years, but it's in a dry, temperature-stable
>> basement.)
>>
>> Best of luck! - Ian
>> On Nov 20, 2014 12:32 PM, "Jacob Ritorto" <jacob.ritorto at
gmail.com>
>> wrote:
>>
>> > Hey all,
>> > I've been getting the bug worse and worse to start working on a
>> > real pdp11. The Raspberry Pi / simh emulation is fantastic, but my
>> > hunger
>> for
>> > authenticity is becoming rampant. I haven't run the youngest in my
>> fleet
>> > of pdp11s, the 11/73, since circa 2002 and if I recall correctly,
>> > it was becoming flaky and popping out to ODT inexplicably from time
>> > to time
>> back
>> > then (I think this is the one with the notoriously combustible
>> > power
>> supply
>> > wires that probably haven't been ECO'd yet -- need to get to that
too).
>> > It's been lying in a warehouse in western Pennsylvania with no heat
>> > and
>> a
>> > lot of dust. So, worst case, we're talking temperature transients
>> around
>> > 110 F and -20 F with no protection. It did stay quite dry.
>> >
>> > Think it'd be bad to simply blow the dust off and fire it up?
>> >
>> > thx
>> > jake
>> >
>>
>
>
22 Nov
22 Nov
2:33 p.m.
Thanks for the replies. Hope to remember enough about electronics and
get enough guidance to be able to use the diagrams you've made, Rob.
Okay, I opened the power supply and checked for corrosion (none at all),
worked back and forth all of the push-on connectors thoroughly and replaced
the PSU into the chassis. I don't yet understand where to insert the
resistors, but I guess anywhere there's 12v and 5v would be sensible.
So now, with no boards at all in the chassis, I do at least get a few
lights on the little front panel but unfortunately not the "DC OK" light
and still no fans. To get them to stay on, I have to kind of 'trick' the
PSU by turning it off, waiting a second, then turning it back on.
While I'm not stickler for perfect authenticity, I do respect it to a
degree. So I'm wondering but am hesitant to ask: Would it be more sensible
to just buy a commodity PC power supply that has lots of 5v and some 12v,
find a way to bolt it in and rework the wiring to fit? Or do you think
it's likely I'll be able to bring this power supply back to safe, reliable
condition without getting in over my head?
Suggestions on where to begin tracing the thing would be most welcome,
please and thanks!
It's been some decades since I've dealt with electronics at this level of
detail and in the interim, someone has made off with my nice fluke meter,
so I don't even have anything to check volts with at the moment. Going to
find another now. Got lots to re-learn here; thanks for bearing with..
--jake
On Fri, Nov 21, 2014 at 2:33 AM, Robert Jarratt <robert.jarratt at ntlworld.com
wrote:
> There is no printset that I am aware of the for the H7864 PSU. I have a
> dead one of these too, I do know which component failed but I don't know
> *why* it failed. As part of that diagnosis I have made a partial schematic
> of a couple of parts of the boards.
>
> The schematic for the Primary Control Module is here:
> http://1drv.ms/1yBzYTN (png) or here: http://1drv.ms/1xFXUnR (Eagle
> schematic). I may not have drawn it logically, and may have some bits
> wrong, as it is quite difficult to derive the schematic and it is easy to
> make mistakes. I don?t know how to identify zener diodes, so all diodes are
> drawn as ordinary ones. I was also unable to draw the transformers
> correctly as I don't know their spec and pinout.
>
> Regards
>
> Rob
>
> > -----Original Message-----
> > From: cctech [mailto:cctech-bounces at classiccmp.org] On Behalf Of Jacob
> > Ritorto
> > Sent: 21 November 2014 05:46
> > To: General Discussion: On-Topic Posts
> > Subject: Re: 11/73 (ba23) bringup after 12 years in deplorable storage
> > conditions
> >
> > Well, things inside were clean and pretty minimally configured, so,
> with all
> > apologies, I jumped the gun and applied power, but I'm afraid the old
> girl just
> > didn't survive the twelve years of temperature transients.
> >
> > The illuminated ba23 power rocker switch lights up, but that's
> absolutely it.
> > No fans, no familiar power supply squeal, no drive spinup, nothing on the
> > seven-segment CPU state display on the rear. Seems thoroughly dead.
> >
> > I guess I need to start tearing it down and debugging the power supply
> as I
> > recall that it was at least doing more than this before the years of bad
> storage.
> >
> > So I need to find power supply diagrams and start tracing things out,
> right?
> > Any ideas as to where to begin?
> >
> >
> > On Thu, Nov 20, 2014 at 4:34 PM, Jacob Ritorto <jacob.ritorto at
gmail.com>
> wrote:
> >
> > > Good deal. I guess I'm just gonna go for it after a cursory
> > > inspection and dusting. It has stayed utterly dry; just the temp and
> > > dust were concerns. I'll report back in a while.. Thanks!
> > >
> > > On Thu, Nov 20, 2014 at 3:55 PM, Ian S. King <isking at uw.edu wrote:
> > >
> > >> At the very least, take a good long look at the power supply and its
> caps.
> > >>
> > >> Has the storage, as bad as it's been, been dry? If not,
you'll
> > >> almost certainly have corrosion all over the place, especially in the
> > >> fastons ISTR run power to the backplane. (I haven't looked at my
own
> > >> 11/73 in a few years, but it's in a dry, temperature-stable
> > >> basement.)
> > >>
> > >> Best of luck! - Ian
> > >> On Nov 20, 2014 12:32 PM, "Jacob Ritorto" <jacob.ritorto
at gmail.com>
> > > wrote:
> >
>>
> > >> > Hey all,
> > >> > I've been getting the bug worse and worse to start working
on a
> > >> > real pdp11. The Raspberry Pi / simh emulation is fantastic, but
my
> > >> > hunger
> > >> for
> > >> > authenticity is becoming rampant. I haven't run the youngest
in my
> > >> fleet
> > >> > of pdp11s, the 11/73, since circa 2002 and if I recall correctly,
> > >> > it was becoming flaky and popping out to ODT inexplicably from
time
> > >> > to time
> > >> back
> > >> > then (I think this is the one with the notoriously combustible
> > >> > power
> > >> supply
> > >> > wires that probably haven't been ECO'd yet -- need to get
to that
> too).
> > >> > It's been lying in a warehouse in western Pennsylvania with no
heat
> > >> > and
> > >> a
> > >> > lot of dust. So, worst case, we're talking temperature
transients
> > >> around
> > >> > 110 F and -20 F with no protection. It did stay quite dry.
> > >> >
> > >> > Think it'd be bad to simply blow the dust off and fire it
up?
> > >> >
> > >> > thx
> > >> > jake
> > >> >
> > >>
> > >
> > >
>
>
3:57 p.m.
-----Original Message-----
From: cctech [mailto:cctech-bounces at classiccmp.org] On Behalf Of Jacob
Ritorto
Sent: 22 November 2014 22:33
To: General Discussion: On-Topic Posts
Subject: Re: 11/73 (ba23) bringup after 12 years in deplorable storage
conditions
Thanks for the replies. Hope to remember enough about electronics and get
enough guidance to be able to use the diagrams you've made, Rob.
Please be aware that the diagram I did is only for the part where I have had a failure
(Q301), and the diagram is not drawn logically (because my understanding on SMPSs is
limited. I also keep finding mistakes, in fact I had to re-upload it again a short while
ago.
Okay, I opened the power supply and checked for corrosion (none at all),
worked back and forth all of the push-on connectors thoroughly and replaced
the PSU into the chassis. I don't yet understand where to insert the resistors,
but I guess anywhere there's 12v and 5v would be sensible.
So now, with no boards at all in the chassis, I do at least get a few lights on
the little front panel but unfortunately not the "DC OK" light and still no
fans.
To get them to stay on, I have to kind of 'trick' the PSU by turning it off,
waiting
a second, then turning it back on.
While I'm not stickler for perfect authenticity, I do respect it to a degree. So
I'm wondering but am hesitant to ask: Would it be more sensible to just buy a
commodity PC power supply that has lots of 5v and some 12v, find a way to bolt
it in and rework the wiring to fit? Or do you think it's likely I'll be able to
bring
this power supply back to safe, reliable condition without getting in over my
head?
Seems like yours is working better than mine....
It is very easy to get sucked in, this has happened to me, but if you want these things to
work I think you just have to bite the bullet.
I am hesitant to make suggestions giving my limited knowledge, but if you can use a dummy
load (use some motor vehicle light bulbs) and then use an oscilloscope to check for ripple
on the outputs that might begin to help. Be careful where you connect the scope though as
you can damage it if you try to trace back too far with it. Probably best to use it only
on the outputs. Also I am sure you are aware that there are lethal voltages inside PSUs,
so be careful and make sure any big capacitors are discharged before touching anything.
Suggestions on where to begin tracing the thing would be most welcome,
please and thanks!
It's been some decades since I've dealt with electronics at this level of
detail
and in the interim, someone has made off with my nice fluke meter, so I don't
even have anything to check volts with at the moment. Going to find another
now. Got lots to re-learn here; thanks for bearing with..
I have found that I have had to re-learn the little I knew, and I am learning more and
more. I have found that over time I have had to buy more and more equipment. One of the
biggest lessons for me is to invest in reasonable equipment. I only just bought a
desoldering station, I wish I had done this a long time ago!!
Regards
Rob
3688
days inactive
3690
days old
8 comments
5 participants
participants (5)
-
isking＠uw.edu -
jacob.ritorto＠gmail.com -
js＠cimmeri.com -
robert.jarratt＠ntlworld.com -
roeapeterson＠gmail.com