[Info-vax] MIcrovax 3100-98

[Scott Dorsey]

On 11/2/2019 10:08 AM, Michael Moroney wrote:
> Aside: I have a VT220 which seems to have a similar power supply issue.
> Symptom is when powered on it seems to be 100% dead as if no power or a fuse
> is blown, but sometimes it would power on and be perfectly fine until powered
> off.  "Sometimes" became less frequently and now it is "never".  Maybe some day
> I'll dig it out and try to replace power supply caps, or maybe not.

Oh, if you see this symptom on MOST equipment with switching supplies, it is
apt to be the kickstart capacitor, usually a 50V cap of only a few MFD
located close to the PWM chip.

However, on a VT220 there are a lot of voltages that are derived off the 
monitor sweep and all kinds of weird things can happen if the sweep does not
come up properly.  It is a strange beast.
--scott


-- 
"C'est un Nagra. C'est suisse, et tres, tres precis."