HP-97 repair questions (a lot of)

[x34]

Got a giant lot of HP-97 and paraphernalia on local auction, including boxes, bag, papers, program listings (one with author's autograph, sic!), HPCC membership card, sealed original HP paper 6-pack, original and working (rebuilt) battery packs, etc. Lucky me!

But, easily predictable for 1979 item, there are two problems:

1. mag card reader, which I know how to repair.
2. printer does not advance paper properly - guess, feed mechanism should be fixed.

So, please, help me with fixing printer. The feed mechanism advances paper a bit,
one side better than other. Does it have two rubber rings on single shaft to do it?
May be, replacing the rubbers would fix it?

I could not find any photos and detailed info on fixing printer's paper feed mechanism. If you where to find such info and photos, please help me.

What are the differences with PICK version and motherboard revisions? How can I tell motherboard version and PICK chipset?

HPMUSEUM says Topcat series has opto-electrical keyboard, am I correct? Any details?

Seeking more info on NNNs, graphical/character printing hacks.

TIA, x34


I'm VERY interested in this marvel.

[Paul Dale]

First rule: do NOT EVER try to run these from the charger. Either ensure a good charged battery pack is present is solder a decent regulated power supply to the appropriate points on the PCB.

If you happen to have a spare board with a working CPU, I'd be interested. I've got a poor 97 with a toasted processor


Pauli

[x34]

Pauli, besides the original (black sealed batteries with red warning) non-working pack fortunately I have working pack, repaired by the original owner.

No, I don't have spares, sorry.

[Accutron]

The 97 uses two different PIK revisions: 1820-1723 and later 1820-1952. The mainboard has two primary revisions. Machines made after the introduction of the 97S have unpopulated vias configured like a DIP socket where the BCD interface pod would attach in a 97S. Pre-97S mainboards can either have tinned or gold traces. The post-97S mainboard always has gold traces, and is electrically identical to the pre-97S revision AFAIK. There are also a number of different ACT, CRC and RAM/ROM chip revisions. First-year machines have an inverse trig bug you can easily test for. Topcats have linear travel keys with coil spring return which close electrical contacts (no optical components, but it's the best keyboard they ever used in a small machine.)

[Dave Frederickson]

(07-18-2016 07:25 AM)x34 Wrote:  But, easily predictable for 1979 item, there are two problems:

1. mag card reader, which I know how to repair.
2. printer does not advance paper properly - guess, feed mechanism should be fixed.

So, please, help me with fixing printer. The feed mechanism advances paper a bit,
one side better than other. Does it have two rubber rings on single shaft to do it?
May be, replacing the rubbers would fix it?

I could not find any photos and detailed info on fixing printer's paper feed mechanism. If you where to find such info and photos, please help me.

Did you try the 97 Service Manual from the MoHPC flash drive? Yes, there are two pinch rollers.

[Paul Berger (Canada)]

(07-18-2016 07:25 AM)x34 Wrote:  Got a giant lot of HP-97 and paraphernalia on local auction, including boxes, bag, papers, program listings (one with author's autograph, sic!), HPCC membership card, sealed original HP paper 6-pack, original and working (rebuilt) battery packs, etc. Lucky me!

But, easily predictable for 1979 item, there are two problems:

1. mag card reader, which I know how to repair.
2. printer does not advance paper properly - guess, feed mechanism should be fixed.

So, please, help me with fixing printer. The feed mechanism advances paper a bit,
one side better than other. Does it have two rubber rings on single shaft to do it?
May be, replacing the rubbers would fix it?

The most common problem is the "rubber" tires on the paper feed shaft get hard and smooth, I have successfully replaced them with a slice of silicon tubing, but unfortunately you need to partially disassemble the printer to get to them. Another thing that can go wrong the rubber rolls are advanced using a cam and ratchet and I have seen cases where the teeth of the ratchet don't engage properly causing the paper to not feed properly. If the feed rolls are just slipping, if you put some slack in the paper on the input side so that it is not pulling the paper off the roll it will probably feed ok until it takes up the slack.

When putting the printer back together, the advance cam fits into a slot in the print head carrier if it is not in that slot the paper will not feed.

Paul.

[Dave Frederickson]

When working on the card reader or printer it's handy to have a cable insertion/removal tool like the one in the manual, P/N T-155435. One can easily be made from a piece of sheet metal available from the local hobby shop. I believe the piece I used was 0.009 inches thick. After cutting it to size and smoothing the edges I applied a piece of Kapton tape on one side of one end to be oriented towards the cable to help protect it.

Note that the ribbon cable connectors have "teeth" in them. Without the tool the cable can become shredded.

Dave

[x34]

Thanks a lot! Completely forgot about service manual.