I repaired a HP9100A calculator but still need some help...

[lhf]

Hi,
I'm new to this forum and I'd like to say hello to everyone. I'm a collector from China and I've collected few calculators in the past few years, including HP35 and HP45.
Last month I was very lucky to know that someone discovered a HP-9100A in a scrap yard in Hong Kong. This has long been my dream machine. Even though it wasn't in good condition and doesn't work, I still bought it.
The calculator was severely damaged, the keyboard frame cracked into pieces and the aluminum shell was even cracked. Luckily the CRT survived. I did a throughout cleaning and tried to fix it.
Unfortunately I made probably the worst mistake in my life --- Maybe I was too tired staying up all night servicing the machine, I mixed up the horizontal deflection board and the vertical deflection board. Strangely they fit into the sockets very well. When I powered the machine up, the 200V deflection voltage immediately damaged some transistors on the two boards plus some transistors and a resistor in the main body. Future inspection shows that the damaged transistors are all related to one of the core memory INHIBIT/SA channels.
I spent almost one month and finally managed to fix the logic. For safety I disconnected the 4KV generator by removing the fuse, and used an oscilloscope in X-Y mode as display. I used 2N3906 to swap the dead transistors marked 'S24851', and used 2N3904 to replace the '2N2218' which drives the inhibit line. The 2N3906 works in some cases (e.g. on the flip flop board), but fails when used on the sense amplifier. I spent a long time to discover that, during which I tried several models of transistors. Finally I got two transistors from one flip-flop board to use on the SA board and the problem was gone.
When I switch to the original display and reconnected the fuse, there was no HV output. Then I found the power transistor on the HV board (RCA 4 322?) was dead. I replaced it with TIP-41C and finally the machine came back to life, with original CRT working...
I took a lot of pictures during the process and posted on a Chinese forum. It may be the most detailed teardown of a HP-9100A calculator so far. You can see the pictures here:
http://bbs.mydigit.cn/read.php?tid=1603729
Sorry it is in Chinese...

Finally, I'd like some help here. I want to know what's the best alternative of the original transistors. Here are the broken ones which I can't find any information:
(From the deflection board)
Motorola 3-016
Motorola 3-203

(From the inhibit/SA board and also the flip-flop board)
Fairchild S24851 007

If you have a spare HP9100A or HP9100B laying around, or just the boards, I'd also like to have the components below so I can repair my little machine just like how it was:

-The keyboard frame;
-The original 'HP-9100A' label on the right of the CRT
-An Inhibit/SA board (For the transistors and a blown resistor);
-The Vertical/Horizontal deflection board;
or
-5x S24851 transistors (they are widely used in this machine);
-1x 2N2218 transistor from SPARGUE (on the inhibit driver);
-13.7Ohm resistor connected to the 2N2218 on the inhibit driver board;

I can pay for the parts and shipping costs if needed.
I'm also willing to share some suggestions if you are repairing a HP-9100 calculator. Of course the first suggestion is --- NEVER PLUG THE DEFLECTION BOARDS IN THE WRONG PLACE!

Best regards,
LHF(James)

[isanchez]

Hi,

my name is Ignacio, and I live in Spain.
I have an HP9100B also to restore/repair.
Congratulations because it seems you are in the way to make it work. Unfortunately for me I am not that wise.

I have checked the link, but cannot see any picture. I would appreciate is I could take a look at them.
You can contact me by email (gmail: "sanreig"), if you want, and maybe we can help each other.

Thanks and good luck.

Regards

Ignacio

[lhf]

(04-06-2016 02:52 PM)isanchez Wrote:  Hi,

my name is Ignacio, and I live in Spain.
I have an HP9100B also to restore/repair.
Congratulations because it seems you are in the way to make it work. Unfortunately for me I am not that wise.

I have checked the link, but cannot see any picture. I would appreciate is I could take a look at them.
You can contact me by email (gmail: "sanreig"), if you want, and maybe we can help each other.

Thanks and good luck.

Regards

Ignacio

Thank you Ignacio! I didn't realize that guests can't see pictures in that forum until your reply...
I just uploaded the teardown to Flickr. Sorry I don't have time to add comments on them. And I'll be happy to help you with your 9100B :-) What's the problem?

Finally the Flickr gallery is:
https://flic.kr/s/aHskxNGuJE
Hope you could see the pictures this time...
Best regards,
LHF

[Massimo Gnerucci]

(04-06-2016 04:13 PM)lhf Wrote:  

(04-06-2016 02:52 PM)isanchez Wrote:  Hi,

my name is Ignacio, and I live in Spain.
I have an HP9100B also to restore/repair.
Congratulations because it seems you are in the way to make it work. Unfortunately for me I am not that wise.

I have checked the link, but cannot see any picture. I would appreciate is I could take a look at them.
You can contact me by email (gmail: "sanreig"), if you want, and maybe we can help each other.

Thanks and good luck.

Regards

Ignacio

Thank you Ignacio! I didn't realize that guests can't see pictures in that forum until your reply...
I just uploaded the teardown to Flickr. Sorry I don't have time to add comments on them. And I'll be happy to help you with your 9100B :-) What's the problem?

Finally the Flickr gallery is:
https://flic.kr/s/aHskxNGuJE
Hope you could see the pictures this time...
Best regards,
LHF

Great pictures James, thank you!

[isanchez]

IMPRESSIVE!!
Congratulations!!!
This makes me happy, because I find my HP911B is in better state than yours was!!! And mine is in a poor state! ;-D

If you ask me about mine: I would say, I don't know how and where to start...
- It does not display anything. But the CRT shows a light point and I have to say that after repeating many turns on tries, it showed numbers...not now.
- It is supposed that it is matter of transistors...but how do you check them?...I heard something using a cold spray?, but not sure.

Maybe we can keep the contact directly through the email sanreig@gmail.com . I don't want to bore the rest of the forum users.

Thanks and kind regards!!!
Again Congratulations...this experience gives me hope!

Ignacio

[jebem]

(04-06-2016 04:40 PM)Massimo Gnerucci Wrote:  

(04-06-2016 04:13 PM)lhf Wrote:  Finally the Flickr gallery is:
https://flic.kr/s/aHskxNGuJE

Great pictures James, thank you!

Fantastic good looking pictures and that machine is amazing!
Thank you for sharing, and lease keep posting the repair procedures.
I'm sure there are here a lot of people interest in following this project.

[HP67]

Mei hao! Great job!

[Jurgen Keller]

VERY nice gallery, thanks a lot for sharing the pictures!

[Lithium]

Beautiful work! Thank you for the gallery.
These machines were really well built.

[Jeff_Kearns]

(04-05-2016 06:33 PM)lhf Wrote:  You can see the pictures here:
http://bbs.mydigit.cn/read.php?tid=1603729
Sorry it is in Chinese...

With a simple click on 'Translate this page', I got a very good English translation of the entire post - all 349 sentences (8,857 words)! Worthy of inclusion as an annex in Geoff's book perhaps? Google Translate has come a long way indeed.

Reads like a tome. And what an amazing job you did with the restoration! The Flikr pictures are great and this post is one of the reasons I enjoy visiting the HP Museum forum so much.

Jeff

[rprosperi]

Amazing set of tear-down photos. I'd say it's safe to claim this as the best documented tear-down of a 9100A, or perhaps of any similar machine as well.

Thanks for sharing these here!

Note: I found many photos on pages 2 and 3 would not load, even after refreshing the page several times, but still incredible.

[lhf]

I'm happy that you appreciated my teardown and pictures. In fact disassembling different machines have long been one of my greatest interests. I also have some nice pictures of an HP-45, a Sharp EL-805 (first handheld LCD calculator with amazing glass circuit board), and a Unicom-141p (the very first machine with microprocessor inside [Intel 4004]). I think most of you will feel interested and I'll put them into my flickr gallery in the future...
BTW I'll keep finding the replacement parts for my HP-9100A, and if you could help, don't hesitate to contact me :-)
Thanks again!
Best regards,
LHF (James)