Threaded Mode | Linear Mode

Geoff Quickfall · (This post was last modified: 03-21-2017 08:38 PM by Geoff Quickfall.)

Well here are the diassembly pictures:

The top is off, only two screws!

[Image: IMG_4443_zps3hnuacyb.jpg]

The components removed:

[Image: IMG_4451_zpsoobty5cd.jpg]

The tape drive which is going south for updating (modifying) to new QIC tapes:

[Image: IMG_4453_zpsgipaoo8b.jpg]

The printer which is fully functional but will be disassembled, cleaned and lubricated:

[Image: IMG_4452_zpsr5uzg3b8.jpg]

The display (alpha numeric LED dot matrix):

[Image: IMG_4459_zpsxrdbmpoj.jpg]

The memory boards:

[Image: IMG_4442_zpsyhwh4uc6.jpg]

To date I have cleaned:

- the outer shell.

- all connectors.

- removed third party labels.

- dissembled most of the printer and reassembled.

Then I looked at the keyboard:

In situ:

[Image: IMG_4450_zpsji9kfidt.jpg]

Obverse:

Reverse:

which had a few sticky keys (the old coffee, two cream and sugar sticky: no, not by me!). This is the low profile 'chicklet' keyboard. In fact on occasion at start up I got "error 30" in a repeated beeping loop; which indicated an undefined function key. This was pinpointed to the f2 key being stuck down and when wriggled was okay. Now the first generation were all screws; in figure three the reverse side of the keyboard the solder dots (heatstakes) were ALL screws. Of course that makes diassembly a dream if not tedious. Unfortunately, I have the 11 screw and all remaining are solder heatstakes. So a very tedious desolder for diassembly.

After referring to two experts, Tony Duell in London (thanks Tony) and Larry Atherton (tape drive and all around 98xx expert in California, thanks Larry) the advise was to desolder to diassembly the keyboard sandwich. So I disregarded these two advises with the following caveat: if what I did did not work then a full diassembly would follow: so be advised, my option is not the advised method.

Now I have done this with separate PC keyboards and many heat staked HP calculator keyboards. I washed the keyboard in warm soapy water letting it soak and agitating the keys with a large paint brush. Both sides. This was followed by a luke warm rinse (many, many times). A full drain of the keyboard after each rinse. I let the water run over the keyboard for a length of time to remove any soapy residue. The reverse of the keyboard contains pores under the keys and extra pores allowing for water to drain.

I placed the keyboard on edge and allowed a fan to blow over the obverse for a day then the reverse. Occasionally using a hair dryer on medium to augment the flow. I placed the keyboard in a large box packed with 4 by 4 inch cloth silica drying pouches and covered it with the pouches. I then left for a four day trip.

Upon return the keys all clicked perfectly, no sticking. I introduced deoxit gold into each pore thereby coating the key contacts with contact enhancer and contact corrosion inhibitor. I have subsequently reassembled the computer minus the tape drive and now have a clean, perfectly functioning keyboard saving the dreaded desolder step. With the tape drive removed the start up error 43 occurs: "tape transport failure", which makes sense and can be interpreted as "where is the tape drive?". Proving the keyboard is functional it was removed and it is back in the drying box until the tape drive is updated.

This machine came with the systems programming, string advanced programming and general IO and extended IO ROMs plus the 15kb memory option. It was fully functional except for the taped drive.

The LED display is wonderful and the HPL language is intuitive to programmers. Can't put it in the flight bag though!

Cheers, Geoff

You might remember this picture taken a 2008, same computer, just sitting waiting for attention:

[Image: office3.jpg]