[Boatanchors] [Milsurplus] Freq Counter

[Rob Atkinson]

Gently unplug and plug in anything that is in a socket.  Wiggle wires
gently.  sometimes things come back to life.   Also, look for switches
and controls and work them back and forth.

Powering with wall wart:  Check the w.w. for both polarity and dc v.
Some say 9 v. but read much higher on a VOM.  They may not have great
regulation but it's better to be a little under v. than way high.
Modern appliances are made to tolerate a wider range of supply voltage
so the w.w. design and construction is loose.   Anyway, don't take the
v. specification on the w.w. at face value.

Rob
K5UJ

On Fri, Jul 13, 2018 at 7:17 PM, Michael Bittner <mmab at cox.net> wrote:
> Hue, thanks for the tip.  There is a 33.3 Ohm power resistor between the power input and the positive terminal of the one electrolytic in the whole thing, a 1000 uF, 50-Volt cap with its negative lead at ground.  So that settled the polarity issue.  Although its VR is an LM 340T5 which is a 5-Volt regulator, I guessed it would be OK to try it on 9 and 12 VDC.
> https://photos.app.goo.gl/fuDnNYb2AJvJtCXX8
> It worked on 9 and 12 VDC, but only the two least signifacant digits lit up.  So, its either another swap meet 5 bucks shot or I can somehow fix it.  It has only 4 ICs and they are all in sockets. One a 74LS196, but the other three have what appear to be house numbers so it may not be fixable.
>
> Mike, W6MAB
>