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I just aquired a 9825A that has a bad key problem. I tried to access the keys , but could remove the last board from the front bezel that seems to to be glued (I unscrewed all the small screws). Does someone had a similar problem ?

I also cannot have the printer work, despite an external good appeareance. no obvious problem.

I would like to find a tape that fit the 9825A. Can I use a modern tape? if yes where can I find it ?

Thanks

Olivier

For the keyboard : Once you've removed all the little screws (and there are a lot of them), the PCB will come free. It may seem to be stuch down by the plastic layer over the dome contacts, but it's not really fixed. Carefully prise (pry) it up from one edge, I think. Or at least that's how the 9831 keyboard comes apart.
Be warned that if you do this, the keys are all loose and will fall out. Make a diagram of where they go before removing the PCB.
For the printer : Does it do anything? Does it feed the paper? Does it make any mechanical noises? Does anything appear on the paper (you are using HP thermal paper, right?)

Hi Tony,

For the keyboard, this is what I supposed, but even exercising a reasonable prying effort, it seems to be stuck. May be it is because of the age, the plastic layer (a very thin transparent layer that I see from the edges) has melt into a kind of glue or something. I will try to submit a more powerful pulling effort.

For the printer, despite paper , when I turned on the key "prt all" after the first input (I assume it should print what I wrote), it display "error 15" which translate to "paper problem or printer failure".
Can a component has gone bad?
I tried to unmount everything and clean everything, up to the board that is in contact with the printer and the roll that support the board.

I assume I should be able to do two kind of tests :
1) see the paper moving forward (paper advance). But I do not know the command to do that (I do not have the manual yet, I ordered it from computer museum, but I do not have it yet). DOes someone know the command ?
2) print command . How do I print a result or a string with it ?

Thanks

Olivier

As far as I can tell, the only 'feedback' from the printer to the rest of the machine is the out-of-paper sensor. Problems with the printhead or solenoid driver can't be detected automatically.
In whcih case, I'd suggest investigating the paper sensor. There's an LED and phototransistor on the little PCB on top of the printer. These connect to a circuit built round one section of an LM339 comparator (U11 in my notes, but this is not the offical HP designation) on the keyboard/display/printer interface. The output of that comparator goes to a shift register that's connected to the keyboard/display/printer controller chip (the big 40 pin on on that PCB).
Since you imply the keyboard and display are fine, I'd not suspect the controller chip or the shift register at this stage.
But I would check the paper out circuit. Trace the connection from the yellow wire to the paper out sensor to the -ve input of the comparator (IC11c in my notes) so you find the right chip. Then look at the output of this comparator with a logic probe (or similar) when you insert or remove paper from the printer. If it doesn't change state (or if it's not a valid TTL voltage level), debug this circuit. It's not complicated.