Similar to HP 46 ??

[Katie Wasserman]

(03-26-2015 02:38 AM)nn7d@msn.com Wrote:  I can't do much more without a service manual or at least some diagrams. I see there is an operators manual available for $10 which I will order. Does anybody know where I can get a service manual?

Pretty much all the user and service manuals that are available for HP calculators (and a lot more stuff) are available here. The 46 service manual doesn't have much in the way of schematics they mostly tell you how to test the unit and swap boards.

Quote:The machine is absolutely beautiful inside. It even smells new. The print ribbon looks barely used, I'd be willing to bet it is the original ribbon.

It's almost certainly dried out. Fortunately these are still made and easy to buy, look for Porelon 483-B/R.

Even if the 15 volt measures ok, try replacing the capacitor. I've found that they are almost always bad and will cause the hammers to not strike or to strike at the wrong time, printing the wrong characters (or nothing).

[nn7d@msn.com]

I have decided that the printer itself is OK. The print drum spins. I can cause the paper to advance. I can raise the two color print ribbon. I can selectively operate all of the hammers. I know that the calculator functions normally in the display mode. Each of the printer functions mentioned above is preceded by what looks like RCA TTL logic circuits 1820-0946. I am searching for a data sheet for this chip which one source identified as a positive NOR gate. After I find the pin-out for this chip, I can check the inputs and outputs to see why it is not activating the transistor drivers for the hammers. Since all printer functions are affected, I suspect an over-all inhibit input which could even be coming from the keyboard printer on/off switch. But, I've got to work my way back systematically.

Rich

[Katie Wasserman]

(03-27-2015 04:44 PM)nn7d@msn.com Wrote:  I have decided that the printer itself is OK. The print drum spins. I can cause the paper to advance. I can raise the two color print ribbon. I can selectively operate all of the hammers. I know that the calculator functions normally in the display mode. Each of the printer functions mentioned above is preceded by what looks like RCA TTL logic circuits 1820-0946. I am searching for a data sheet for this chip which one source identified as a positive NOR gate. After I find the pin-out for this chip, I can check the inputs and outputs to see why it is not activating the transistor drivers for the hammers. Since all printer functions are affected, I suspect an over-all inhibit input which could even be coming from the keyboard printer on/off switch. But, I've got to work my way back systematically.

According to this source it's a CD4001, CMOS quad 2-input NOR gate.

[nn7d@msn.com]

Katie,

Thanks again. That's an excellent cross reference. It will save me a lot of time.

Rich