Date   

Re: Troubleshooting a 9845C

 

Dave,

 

If the mainframe is the problem, it’s most likely caused by bad ROM’s and then you have to replace them by a ROM board.

https://hp9845.net/9845/projects/romboard/

 

-Rik

 

Van: VintHPcom@groups.io <VintHPcom@groups.io> Namens Rik Bos
Verzonden: zondag 2 februari 2020 11:54
Aan: VintHPcom@groups.io
Onderwerp: Re: [VintHPcom] Troubleshooting a 9845C

 

Dave,

 

The 9845C uses the same graphic subsystem as the 9845B option 200 so it is possible to use a 98780A monitor instead of the color 98770A monitor.

The color monitor is a very complex peace of work with 3 independent power supplies build in. Because of its complexity and power hunger it has 2 fans one on the outside one on the inside.

It is also very sensitive for overheating, if the power transistors won’t get enough cooling they will be destroyed. Most of the time this will result in a short and destroy the driver transistors also.

First thing to do is building a turnon fixture to start the 9845C without a monitor to narrow down the problem.  https://hp9845.net/9845/tutorials/testrom/images/turn-on-fixture-schematics.png

https://hp9845.net/9845/tutorials/testrom/

If the system doesn’t beep it’s the monitor.

 

BE VERY CAREFULL LETHAL VOLTAGES EVEN WHEN THE UNIT HAS BEEN SWITCHED OFF!

The big capacitors keep the power for some time, it takes them a few minutes to discharge fully.

 

Monitor fault finding, first download the service manual for the 98770A monitor and the diagrams. (I’ve printed the diagrams on A3 that works for me)

Next remove the outer casing of the monitor, place the monitor on the 9845C and connect both to the main power.

Switch on the 9845C and look at the power leds on the left side of the monitor, just only the rightest LED should light, all other should be off.

If more led’s are lighting, remove main power, take a small break go to the toilet etc..

Remove the cover of the power and remove the power supply board, check the power transistors (separate board), rectifier board and capacitor board for the obvious.

You should probably replace all the ELCO’s for new ones, after 30-40 years they’re worn out and developing high ESR. (Maybe do this first before initial power on.)

When you replace a power transistor also check the drivers on the main board, If the power transistors keep dying probably one of the small driver transformers has gone bad.

 

Hope it helps

-Rik

 

 

 

 

Van: VintHPcom@groups.io <VintHPcom@groups.io> Namens Dave via Groups.Io
Verzonden: vrijdag 31 januari 2020 23:12
Aan: VintHPcom@groups.io
Onderwerp: [VintHPcom] Troubleshooting a 9845C

 

I recently, after a long search and much patience, managed to acquire an option 200 power supply for my option 200 9845C.  I finally had a chance to power it up, after verifying voltages on the supply.

The fans run on the base and monitor, and the paper advances.  I get a beep on power up, but no video.  After 20 seconds or so, the systems starts beeping; a series of short beeps in rapid,nonstop succession.

before the rapid beeping, I tried the "XXX" and EXECUTE, with no result.

I plan to dig in a bit more methodically when I have some time, but I would be grateful if anyone here has any suggestions.

Thanks in advance!

Dave

Dave


Re: Troubleshooting a 9845C

 

Dave,

 

The 9845C uses the same graphic subsystem as the 9845B option 200 so it is possible to use a 98780A monitor instead of the color 98770A monitor.

The color monitor is a very complex peace of work with 3 independent power supplies build in. Because of its complexity and power hunger it has 2 fans one on the outside one on the inside.

It is also very sensitive for overheating, if the power transistors won’t get enough cooling they will be destroyed. Most of the time this will result in a short and destroy the driver transistors also.

First thing to do is building a turnon fixture to start the 9845C without a monitor to narrow down the problem.  https://hp9845.net/9845/tutorials/testrom/images/turn-on-fixture-schematics.png

https://hp9845.net/9845/tutorials/testrom/

If the system doesn’t beep it’s the monitor.

 

BE VERY CAREFULL LETHAL VOLTAGES EVEN WHEN THE UNIT HAS BEEN SWITCHED OFF!

The big capacitors keep the power for some time, it takes them a few minutes to discharge fully.

 

Monitor fault finding, first download the service manual for the 98770A monitor and the diagrams. (I’ve printed the diagrams on A3 that works for me)

Next remove the outer casing of the monitor, place the monitor on the 9845C and connect both to the main power.

Switch on the 9845C and look at the power leds on the left side of the monitor, just only the rightest LED should light, all other should be off.

If more led’s are lighting, remove main power, take a small break go to the toilet etc..

Remove the cover of the power and remove the power supply board, check the power transistors (separate board), rectifier board and capacitor board for the obvious.

You should probably replace all the ELCO’s for new ones, after 30-40 years they’re worn out and developing high ESR. (Maybe do this first before initial power on.)

When you replace a power transistor also check the drivers on the main board, If the power transistors keep dying probably one of the small driver transformers has gone bad.

 

Hope it helps

-Rik

 

 

 

 

Van: VintHPcom@groups.io <VintHPcom@groups.io> Namens Dave via Groups.Io
Verzonden: vrijdag 31 januari 2020 23:12
Aan: VintHPcom@groups.io
Onderwerp: [VintHPcom] Troubleshooting a 9845C

 

I recently, after a long search and much patience, managed to acquire an option 200 power supply for my option 200 9845C.  I finally had a chance to power it up, after verifying voltages on the supply.

The fans run on the base and monitor, and the paper advances.  I get a beep on power up, but no video.  After 20 seconds or so, the systems starts beeping; a series of short beeps in rapid,nonstop succession.

before the rapid beeping, I tried the "XXX" and EXECUTE, with no result.

I plan to dig in a bit more methodically when I have some time, but I would be grateful if anyone here has any suggestions.

Thanks in advance!

Dave

Dave


Re: Troubleshooting a 9845C

François Lanciault
 

Hi Dave,

What is the health of the color monitor power supply ?

On the 9845C, the PSU inside the monitor is usually the "hard to solve" problem. You should check the 98770 service manual and the 98770 schematics for more information and for how to check if the PSU is working correctly. At least, there are no RIFA capacitors on the 98770 monitor PSU (at least none on mine).

If you know for a fact that your monitor PSU is ok then you could try to swap boards if you have another working 9845. If not then maybe the internal ROMs have gone bad and should be replaced.

Good luck with this project ! At least you have a chance to make it work. I am missing to many parts in my 98770 monitor to even start thinking about fixing it. :-(

François

On Jan 31, 2020, at 17:12, Dave via Groups.Io <dfnr2@...> wrote:

I recently, after a long search and much patience, managed to acquire an option 200 power supply for my option 200 9845C.  I finally had a chance to power it up, after verifying voltages on the supply.

The fans run on the base and monitor, and the paper advances.  I get a beep on power up, but no video.  After 20 seconds or so, the systems starts beeping; a series of short beeps in rapid,nonstop succession.

before the rapid beeping, I tried the "XXX" and EXECUTE, with no result.

I plan to dig in a bit more methodically when I have some time, but I would be grateful if anyone here has any suggestions.

Thanks in advance!

Dave

Dave



Re: HP 9821 - display and tape transport issues #VintageHPComputers

mariuszmleczko@...
 

Could you also suggest a way of cleaning the boards from a many year dust
Isopropanol + soft brush or which other cleaning fluid ?


Re: HP 9821 - display and tape transport issues #VintageHPComputers

mariuszmleczko@...
 

What is the diameter and size of O-ring used for 9865A tape transport ? Does anyone know ?


Re: Troubleshooting a 9845C

Paul Berger
 

I am not sure if it is the same on a 9845, but a 9835A does that when it can't find its monitor.

Paul.

On 2020-01-31 6:12 p.m., Dave via Groups.Io wrote:

I recently, after a long search and much patience, managed to acquire an option 200 power supply for my option 200 9845C.  I finally had a chance to power it up, after verifying voltages on the supply.

The fans run on the base and monitor, and the paper advances.  I get a beep on power up, but no video.  After 20 seconds or so, the systems starts beeping; a series of short beeps in rapid,nonstop succession.

before the rapid beeping, I tried the "XXX" and EXECUTE, with no result.

I plan to dig in a bit more methodically when I have some time, but I would be grateful if anyone here has any suggestions.

Thanks in advance!

Dave

Dave


Re: Troubleshooting a 9845C

Jack Rubin
 

Get rid of those RIFA caps - in the power supply and at the AC power inlet - before going too much farther!
--
Jack
www.computerarium.org


Troubleshooting a 9845C

 

I recently, after a long search and much patience, managed to acquire an option 200 power supply for my option 200 9845C.  I finally had a chance to power it up, after verifying voltages on the supply.

The fans run on the base and monitor, and the paper advances.  I get a beep on power up, but no video.  After 20 seconds or so, the systems starts beeping; a series of short beeps in rapid,nonstop succession.

before the rapid beeping, I tried the "XXX" and EXECUTE, with no result.

I plan to dig in a bit more methodically when I have some time, but I would be grateful if anyone here has any suggestions.

Thanks in advance!

Dave

Dave


Re: Disk selector switch for a disk emulator?

rmb_guru
 

On Sun, Jan 26, 2020 at 07:44 AM, Anders wrote:
I have been giving this a bit more thought and I am not SONOS :) With close to 100 PCBs sold, I'd hate to disappoint my existing customers, so what about this:

I create a small extra board that can be connected to the existing board's AUX connector and mounted at right angle to the main board that slides into the box pictured above. On that board are switches for down/up, leds for talk/listen/disk and a small display (NDH-C02-16CZ-FSW-FBW-3V3). In addition to that a DS2417 RTC plus a 20mm coin battery.
This sounds like a great idea that will support the past and provide good features for the future... :-)


Re: HP-9885M service manual.

 

I second that, would be interested to see what it says for the 21MX.
Marc


Re: HP 9821 - display and tape transport issues #VintageHPComputers

mariuszmleczko@...
 

Thank you a lot guys. I got it just a couple of days, haven't opened it yet.
Will do it as soon as I read service manual, maybe around the end of this week.
Last LCD board photo was taken from here (only for reference):
http://www.silicium.org/forum/viewtopic.php?t=43529

The history of model I got is also interesting.
It was used surely during soviet times in polish military factory PIT RADWAR
which is working on radiolocation systems, radio-electronic reconnaissance systems, anti-aircraft defense systems as well as command and fire control support systems
https://historiainformatyki.pl/historia/skan.php?doc_id=1221&type=pdf&for_download=1

Beside the computer and two standard ROM's (Mathematics, PC1), I got also "user definable functions I-III" ROM and three cables shown on the photos below.
https://groups.io/g/VintHPcom/album?id=239610

Do you have any Idea what kind of equipment could have been connected with those (seems reworked plugs) 11203A TTL I/O (female 50 pin d-sub) and 11203A BCD (male 50 pin d-sub) ?


Re: HP-9885M service manual.

François Lanciault
 

Hi Paul,

I will scan the manual and let you know when available.

François


Re: HP 9821 - display and tape transport issues #VintageHPComputers

David Collins
 

From a quick look at the schematics, the display issue will most likely be caused by either;

 

  1. A bad transistor in U14 – check pin 12 with an oscilloscope if you have one – you will probably see no activity but it should instead be similar to pin 10.  Pin 13 on U14 drives the transistor and should show activity in the same way as pin 9.  If there’s activity at pin 13 but nothing on pin 14, then one of the driver transistors in U14 is probably bad – but you could connect in a common PNP transistor to fix it if you can’t find a replacement ; or

 

  1. If there’s no activity at pin 13 of U14, then u12 is probably bad.  U12 appears to be a 74145 IC which is still available on eBay.

 

The problem is I can’t find a board layout that shows which ICs are U12 and U14.  I suspect U14 is one of the 5 ICs on the right side of the displays.  U12 will be one of the 74175s below the displays.

 

I used the schematics here - http://www.hpmuseum.net/document.php?hwfile=6327

 

Hope that helps.

 

David Collins

 

 

From: VintHPcom@groups.io <VintHPcom@groups.io> On Behalf Of Rik Bos
Sent: Monday, 27 January 2020 10:55 PM
To: VintHPcom@groups.io
Subject: Re: [VintHPcom] HP 9821 - display and tape transport issues #VintageHPComputers

 

Hi Marius,

 

Congratulated, you’re one of the few people owning a HP 9821A.

The difference between a 9820 and 9821 is in essential the switch for mag card to cassette drive.

The drive is the same as used in the HP 9830A/B and 9865A tape drive.

 

First, the tape transport on the back side of the drive there are two wheels with a O-ring on it.

The motor drives the wheel by pressing the drive shaft to the O-ring if the O-rings are deteriorated the tape transport won’t work properly.

See the pictures: https://www.flickr.com/photos/hp-fix/5445928267/in/album-72157630819381098/

https://www.flickr.com/photos/hp-fix/6851031513/in/album-72157630819381098/

Replacing them is easy.

Another thing is the leader of the tape should be transparent and there must be a reflective coating (white, silver, etc..) on the inside of the left side of the tape housing.

So the small lamp can shine trough the tape leader and the light will be reflected on the LDR placed next to the lamp forming the EOT sensor.

https://www.flickr.com/photos/hp-fix/7676311616/in/album-72157630820029066/

https://www.flickr.com/photos/hp-fix/9426870925/in/album-72157634915270264/

 

The display, http://www.hpmuseum.net/images/09820-66541-Display-40.jpg

The display is multiplexed and uses column and row drivers, probably one of the row drivers is defective.

They are on the display board; you can use the schematics of the 9820A made by Tony Duell to locate the right IC.

http://www.hpmuseum.net/exhibit.php?hwdoc=52

Be careful when desoldering any components of the board because the vias on these boards will get bad contact problems when there is applied to much heat.

 

Hope this helps a little.

 

-Rik

 

Van: VintHPcom@groups.io <VintHPcom@groups.io> Namens mariuszmleczko@...
Verzonden: maandag 27 januari 2020 11:32
Aan: VintHPcom@groups.io
Onderwerp: [VintHPcom] HP 9821 - display and tape transport issues #VintageHPComputers

 

Hi. I'm in position of vintage computer HP 9821A

Do you have any suspicion which exact part of display board might be broken that it cause such regular failure of every third digit in each of four LED sections  ?
I got also problem with a tape transport. Mechanically seems to be working OK, but during program search or load it stuck in a place trying rotate left and right.

Tape sound and photos here:
https://groups.io/g/VintHPcom/album?id=239610
https://groups.io/g/VintHPcom/files/HP%209821A/tape%20sound.mp3

Thank you in advance for help.


Re: HP 9821 - display and tape transport issues #VintageHPComputers

 

Hi Marius,

 

Congratulated, you’re one of the few people owning a HP 9821A.

The difference between a 9820 and 9821 is in essential the switch for mag card to cassette drive.

The drive is the same as used in the HP 9830A/B and 9865A tape drive.

 

First, the tape transport on the back side of the drive there are two wheels with a O-ring on it.

The motor drives the wheel by pressing the drive shaft to the O-ring if the O-rings are deteriorated the tape transport won’t work properly.

See the pictures: https://www.flickr.com/photos/hp-fix/5445928267/in/album-72157630819381098/

https://www.flickr.com/photos/hp-fix/6851031513/in/album-72157630819381098/

Replacing them is easy.

Another thing is the leader of the tape should be transparent and there must be a reflective coating (white, silver, etc..) on the inside of the left side of the tape housing.

So the small lamp can shine trough the tape leader and the light will be reflected on the LDR placed next to the lamp forming the EOT sensor.

https://www.flickr.com/photos/hp-fix/7676311616/in/album-72157630820029066/

https://www.flickr.com/photos/hp-fix/9426870925/in/album-72157634915270264/

 

The display, http://www.hpmuseum.net/images/09820-66541-Display-40.jpg

The display is multiplexed and uses column and row drivers, probably one of the row drivers is defective.

They are on the display board; you can use the schematics of the 9820A made by Tony Duell to locate the right IC.

http://www.hpmuseum.net/exhibit.php?hwdoc=52

Be careful when desoldering any components of the board because the vias on these boards will get bad contact problems when there is applied to much heat.

 

Hope this helps a little.

 

-Rik

 

Van: VintHPcom@groups.io <VintHPcom@groups.io> Namens mariuszmleczko@...
Verzonden: maandag 27 januari 2020 11:32
Aan: VintHPcom@groups.io
Onderwerp: [VintHPcom] HP 9821 - display and tape transport issues #VintageHPComputers

 

Hi. I'm in position of vintage computer HP 9821A

Do you have any suspicion which exact part of display board might be broken that it cause such regular failure of every third digit in each of four LED sections  ?
I got also problem with a tape transport. Mechanically seems to be working OK, but during program search or load it stuck in a place trying rotate left and right.

Tape sound and photos here:
https://groups.io/g/VintHPcom/album?id=239610
https://groups.io/g/VintHPcom/files/HP%209821A/tape%20sound.mp3

Thank you in advance for help.


HP 9821 - display and tape transport issues #VintageHPComputers

mariuszmleczko@...
 

Hi. I'm in position of vintage computer HP 9821A

Do you have any suspicion which exact part of display board might be broken that it cause such regular failure of every third digit in each of four LED sections  ?
I got also problem with a tape transport. Mechanically seems to be working OK, but during program search or load it stuck in a place trying rotate left and right.

Tape sound and photos here:
https://groups.io/g/VintHPcom/album?id=239610
https://groups.io/g/VintHPcom/files/HP%209821A/tape%20sound.mp3

Thank you in advance for help.


HP 1351A vector graphics generator - I/O boards

Toby
 

Hi,

I'm checking out one of these units. It has the Option 002, 16-bit
binary interface 52106A installed, in place of the standard HP-IB
interface (no part number given in manual as far as I can see).

So I'm looking for the RS232C Option 001 (52105A) or the standard HP-IB
I/O board. And/or documentation on 52106A option.

It's also missing the bottom panel.

Thankfully the service/operation manuals are available online at Bitsavers!

--Toby


Re: Disk selector switch for a disk emulator?

Anders
 

Everyone's vote counts :)


Re: Disk selector switch for a disk emulator?

Steve Leibson
 

Brilliant. A retrofittable idea. I'd vote for that one (if I had a vote).

--Steve


On 1/26/2020 7:44 AM, Anders wrote:
I have been giving this a bit more thought and I am not SONOS :) With close to 100 PCBs sold, I'd hate to disappoint my existing customers, so what about this:

I create a small extra board that can be connected to the existing board's AUX connector and mounted at right angle to the main board that slides into the box pictured above. On that board are switches for down/up, leds for talk/listen/disk and a small display (NDH-C02-16CZ-FSW-FBW-3V3). In addition to that a DS2417 RTC plus a 20mm coin battery.
-- 
Steve Leibson

Phone (Cell): 408-910-5992
Phone (Home): 408-292-4930


Please feel free to link to me on LinkedIn


History site: www.hp9825.com

#Iwork4Intel


Re: Disk selector switch for a disk emulator?

Anders
 

I have been giving this a bit more thought and I am not SONOS :) With close to 100 PCBs sold, I'd hate to disappoint my existing customers, so what about this:

I create a small extra board that can be connected to the existing board's AUX connector and mounted at right angle to the main board that slides into the box pictured above. On that board are switches for down/up, leds for talk/listen/disk and a small display (NDH-C02-16CZ-FSW-FBW-3V3). In addition to that a DS2417 RTC plus a 20mm coin battery.


Re: HP-9885M service manual.

Paul Berger
 

Francois,

I would be interested in seeing that.  I have also successfully connected a 9885 to 9000-332.

Paul.


On 2020-01-25 12:21 p.m., François Lanciault wrote:
Hi,

I just noticed that my original copy of the service manual for the HP-9885M/S is totally different from the one at the HP computer museum. It is a bit larger (7 chapters) and more recent (1981 ?) as it covers the 9835A-qB, the 9845 A-B-C and the HP-21MX. It also comes with a bunch of service notes (last chapter).

I don't think there is that much new informations. I could eventually scan it if there is interest.

I also have a 1982 print of the installation manual but a quick look shows no differences from the 1978 HP museum copy.

François

On Jan 24, 2020, at 12:54, CuriousMarc <marc.verdiell@...> wrote:

I added two missing manuals for the HP 9825: The Printer Manual (for the HP 9866 printer) and the Disk Manual (for the HP 9885 8" Floppy). David and Al, you might want to add this to your collection.