HP 2648 terminal

Tony Duell ard at p850ug1.demon.co.uk
Wed Feb 16 17:56:06 CST 2005


> 
> Ok, finished all negotiations with the seller. Turns out I get to keep the 
> damaged unit.

Good...

[...]

> If anyone has the above parts, please let me know. This all assumes my tube 
> is working. It looks like it's undamaged but I won't know till I power it 
> up.

It's possible there's been damage to the electronics that you've not 
spotted, so I would be careful when powering it up. If you've got a 
cracked trace in the PSU, the output could go through the roof [1]. 

This is one time where you _certainly_ should test the PSU on dummy load 
and add things in small incrememnts. Is it possible to run it without the 
CRT and either get a beep and/or check the video and sync signals with a 
'scope/ At least you'd then know that the digital side was working.

[1] I acutlaly had this in a piece of HP hardware. The connection to the 
output capacitor in a swithcing regualtor was dry-jointed. The result was 
15V spikes on the 5V line. Fortunately the crowbar tripped and saved the 
logic, but I wouldn't want to depend on that!

-tony




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