DECmate III and Rainbow 100+

[Kevin Handy]

Geoff Reed wrote:

>
>> > And yes, the whole thing is powered, rather poorly, from 12 volts.
>> > (Poorly: if you flip significant quantities of white pixels on and
>>
>> I've never had this problem. Are you sure you've not got some dried-up
>> capacitors somewhere?
>>
>> > off, the scan area expands and shrinks very noticeably.  So clearly
>> > the supply regulation is seriously inadequate.)
>
>
> the VR 201 monitors have a couple of points of failure, the most 
> common is a coil (IIRC) in the vertical that is potted in wax, they 
> potted this -before- soldering, and wax tended to get down into the 
> solder joint making a bad joint that fails after a while, there is a 
> resistor right by it that also burns up at about the same time.
>
Are you talking about the flyback transformer, and the 0-ohm resistor?

DEC never seemed to use decent flybacks, as that was the most common
failure I saw in VT220's, VT320's. The flyback would short out, heat up
causing the ceramic casing to crack and ooze goo, and take out a
transistor for good measure. I used to fix these, until the transformer
started costing more than a replacement terminal did.