9815A - New in Open Box - What to do to NOT damage it.

[jeejohn]

I have a HP-9815A that is essentially new in open box, with no extra accessories. I bought it about 25 years ago from a dealer who wanted to get rid of it. As far as I remember, I have had it out of the box twice back when I first bought it and a few years later. I know everything worked the first time. I think at that time I programmed it to run the Savage benchmark. The second time, the printer feed was no longer working. I have never tried the tape drive.

Now I have pulled it out of storage to look it over for a third time. I have not plugged it in, as who knows what would happen to it now after some 25 years of storage, particularly with the power transformer being internal to the machine.

What are your suggestions with how I should proceed with this?

My intent is to eventually sell it.

[teenix]

Seeing that something did work and then didn't suggests that something has broken down inside, probably from age. If the unit has been kept in a dry environment away from a salty beach side atmosphere, the insides should be ok. Some components like electrolytic capacitors might need attention but you would need proper test gear to test them and other components out.

The mechanicals may also need attention with dust collection and the lubricants may have degraded over time and either cannot or should not be used.

The wiring might need attention especially at solder points on circuit boards. These may have corrosion. If everything looks nice and clean inside, this may not be a problem. Avoid moving the wiring too much or you may introduce problems.

Getting hold of a service manual would be a good start if you wanted to check it out.

cheers

Tony

[jeejohn]

The 9815A was kept in the original box with the foam filled plastic covers top and bottom, essentially sealing it in between them. It’s been dry, relatively cool (mostly never above 85 degree F). So there shouldn’t been any issues with dust collection, although the fan filter foam rubber (at the back left side) is just disintegrating. When I try to grab it, it just comes apart with no adhesion to any other part of it.

I imagine that whatever lubricants in there may have started to separate out some of the chemical additives. Also, there’s likely to be out-gassing of some of the various materials and parts like the capacitors. I have obtained a copy of the service manual which indicates that there is a +15V, +12V, +5V, -5V, and -12V power outputs. The power supply was designed to handle 100V, 120V, 220V, 240V at 48-66 Hz inputs.

I found at an another website, about the 9845 which uses the same type of tape machine, that the tape drive and tape cartridges are prone to problems. The synthetic rubber coating used on the capstan apparently “literally melted after years” or are “gooey”. The tape cartridges may have lost parts of their magnetic coating, along with drive belts bonded with the tape, etc. An interesting find is that the tapes have loose ends, using holes in the tape and lights to detect the ends and thus the ends of the tape.

I don’t have the skills to look into any of this, so I guess I’ll post it over on the classifieds to see if there is any interest in it.