Another test would be to disconnect the output and see if that runs the device cooler. Maybe the load, while not a short, is simply too great for the device.
But I am leaning towards the inputs containing spikes that need to be dissipated as heat in clamping diodes. A decent CRO on the device input pins while it is out of circuit will show that as well. Kindest regards, Doug Jackson em: [email protected] ph: 0414 986878 On Tue, 25 Nov 2025 at 09:52, Peter Coghlan via cctalk < [email protected]> wrote: > > > > 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? > > Regards, > Peter Coghlan. >
