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Teletype
March 18th, 2009, 05:42 PM
Greetings.

I have an old HP 2382a office display terminal.

When I turned it on for the first time, it seemed to work fine. I walked away to look up information about it on the net, and when I returned, about an hour later, the screen had gone black, and I was unable to restore it.
When I turned it off, let it cool, and turned it on again, it beeped and the fan worked, but the moniter still remained blank. I know that this computer was heavily used in its day, as some of the icons have burned onto the screen.

Does anyone have a good guess as to what the problem could be and how to fix it? I am sad to say I know almost nothing about computers, and so its probably something simple.

Secondly, I was wondering if anyone knows of a good reference for learning the programing code by which it is operated, Basic right?

Thanks

ahm
March 18th, 2009, 06:33 PM
Does the terminal have a brightness or contrast control?
If so, give them a twirl.

As for using BASIC, you're going to need to hook the terminal up
to a computer that has BASIC on it. The terminal doesn't do anything
other than send and receive data over the serial port.
The only "smarts" it has it to be able to react to certain character sequences
and do stuff like move the cursor or clear the screen.

Cheers,
Andy

Chuckster_in_Jax
March 18th, 2009, 07:02 PM
Try putting your hand or arm very close to the front of the screen. You should feel a static charge. If not, the high voltage section may be out.

modem7
March 18th, 2009, 07:21 PM
According to the Reference Manual at http://www.hpmuseum.net/exhibit.php?hwdoc=421, the single beep indicates a passing of the unit's self test.
Therefore we can be confident that the issue relates only to the 'display' part of the unit.

The unit is old and parts have probably deteriorated. It is possible that the deterioration is such that you see a display when the unit is cold but not when the unit is warm (even with the brightness knob turned up). I know you wrote that you let the unit cool down, but be aware that such a unit may require 30 minutes or more to properly cool down.

As Andy wrote, the unit is not a computer. It would have attached to a large computer, perhaps a mainframe or minicomputer.

Lou - N2MIY
March 18th, 2009, 07:43 PM
I agree with the advice to check for high voltage. If you're unsure, you can also turn up the brightness all the way in a dark room and look for a line or raster.

I just fixed a dec VT100 in the last two weeks that did exactly what your HP terminal did. It too had screen burn, confirming many hours of use. In the end, the flyback transformer had failed. When it went, it took out the fuse on the analog video board. Replaced the fuse and the flyback and got back to business.

Lou

Dwight Elvey
March 18th, 2009, 09:35 PM
Hi
It seems that it is quite common to see the flyback
fail on machines that have been sitting for some time.
I wonder if it might be that moisture that has built up
in the unused transformer. One might place the
flyback in the oven at low temperature for a few
hours before turning it on.
Dwight

modem7
March 19th, 2009, 12:00 AM
One might place the flyback in the oven at low temperature for a few hours before turning it on.
Yes, be careful not to overdo it, otherwise the flyback transformer will become a friedblack transformer.

Teletype
March 20th, 2009, 06:44 PM
Wow, thanks!

So..
Turned it on again. I felt no static at the screen, the brightness controls had no effect, and it had been sitting for over 24 hours.

So its probably the flyback transformer. Should I put it in the oven, or buy a new one, or try the first then second?

If the first, what temp for how long? Don't want to mess this up!


Unfortunatly I don't have any mainframes sitting around :(, but I do have lots of old Apples and IBM clones. Is there software that can simulate a mainframe? Or is there another way?

Thanks!

patscc
March 20th, 2009, 07:15 PM
If the flyback's dead, baking will not help.
Pull the cover off and see if there's a glow in the neck of the tube.
What does OP have in the way of test equipment ?
Don't give up hope yet, it could be something as simple as the fuse in the HOT's B+ line is blown, a HOT that went open, all kinds of stuff before the flyback should bare the blame.
patscc