28 Dec
2009
28 Dec
'09
6:45 p.m.
Old DEC Power Control 861C Hi,
looks like I am not getting the posting in my e-mail but my messages do get
posted.
This issue came up a few months back. Apparently gmail filters the
replies to your own messages somewhere (and not to somewhere sensible!).
Perhaps somebody else can rememebr the details.
I found this replyto my previous message by Tony Duell
<cctalk%40classiccmp.org?Subject=Re%3A%20Old%20DEC%20Power%20Control%20861C&In-Reply-To=%3Cm1NM4jS-000J3uC%40p850ug1%3E>in
the archives.
To follow-up, the 861C emits a crackling noise for the first few seconds (20
or so) and then I can hear a relay chattering (very noisy!).
Also the light on the front panel is flashing continuously (maybe that's
normal.)
old DEC neons tend to flicker randomly (and it's truely random).
The basic design is for the mains :
Mains in--->filter --->Breaker-+--->Unswitched outs
|
+--->Contactor (big relay)-> Switched outs
The contactor is controlled (in the 861) by a reed relay on the little
PCB inside. This has a differentially-wound coil to give the 'ground for
on' and 'ground for off' functionality on the 3 pin connector. The reed
relay coil is powered by a little transformer/rectifier/capacitor
circuit, mostly on the PCB.
My first suspicioun is that capacitor. Open it up and look for any
electrolytics on the PCB inside.
-tony