> -----Original Message-----
> From: Peter Coghlan via cctalk <[email protected]>
> Sent: 24 November 2025 22:41
> To: General Discussion: On-Topic and Off-Topic Posts
<[email protected]>
> Cc: Peter Coghlan <[email protected]>
> Subject: [cctalk] Re: Hot Video Shift Register on VT100
>
> >
> > Sorry if I wasn't clear in my earlier reply, but there were some
> > answers inline. The summary is that Vcc looks fine, there does not
> > seem to be any short on the outputs of the shift register and the chip
> > seems to be working correctly. It just gets hot and I wonder if this
> > could be due to the CLK input being a bit spikier on the VT100 than on
> > my VT102? Could this be why later revisions of the VT100 introduced an
> > inductor on the DOT CLK output from the DC011?
> >
>
> Perhaps one way to test the hypothesis would be to insert an inductor like
> those used on the later revisions in the DOT CLK output and check whether
> a) everything still works and b) the shift register runs cooler?
Yes, I did think of doing this, but I don't like the idea of breaking a
track for this purpose if the outcome is uncertain. I guess maybe even if
this does work the circuit was presumably designed to work fairly hot,
although perhaps the revision added the inductor to reduce the heat?
I will consider it though, but I am not too sure what kind of part to use.
If I have read it correctly the revised print set says "BEAD, FERRITE
.1380DX.380LG", I am not quite sure that this means, although I am sure I
can get ferrite cores. Does that description mean anything to anyone?
>
> Regards,
> Peter Coghlan.
