Reviving VT220?

[Aaron Jackson]

I am taking another look at this.

In this VT220 there is a "Billion" transformer attached to the side
which gives AC to the board via a two pin connector. My multimeter
(which is supposedly true RMS) tells me that there is 246v going into
the transformer (fine, I'm in the UK) and 40v coming out. Is this the
right voltage that the board should be getting? Maybe it is supposed to
be 110v. Would setting the switch on the back to 110v bypass this
allowing me to try it from a 110v transformer?

The logic side of the terminal is fine. I can hook it up to a TV and use
it, but there is no high voltage to power the tube.

The layout of the board in this terminal is slightly different to what
is shown in the block diagram in the schematics, but of the circuit
diagram appears to match for the most part.

Getting a bit confused here.

Thanks,

Aaron.




Aaron Jackson via cctalk writes:

> Hi all,
>
> A colleague and I are trying to get a VT220 working again as it recently
> died on us. We are hoping to set up a few items for the mid-80s
> (including this terminal) to show the graduands what it would have been
> like if they were doing their CompSci degree 30 years ago.
>
> It looks to me like the flyback is dead. There is a lot of soot and
> there looks like there is some damage to the top of the transformer,
> better seen in the second image.
>
> http://www.cs.nott.ac.uk/~psxasj/sparse/flyback1.jpg
> http://www.cs.nott.ac.uk/~psxasj/sparse/flyback2.jpg
>
> The terminal powers on and does the usual beeping but nothing is
> displayed on the screen. Does anyone have any advice about what to do
> here? Are there any sources of compatible flyback transformers?
>
> We have a second VT220 which exhibits the same behaviour, hopefully for
> a different reason so we can try and cobble two into one.
>
> Any thoughts / advice would be greatly appreciated.
>
> Thanks,
>
> Aaron.