[TR] Triumph Bendix Radio

[John Finlayson]

Thanks Randall

I found the main capacitor (Bendix 2092983-0708). Unfortunately no polarity 
markings, at least none that I can see or understand. It's soldered to the 
circuit board. There may be markings on the underside but I can't get at 
them. It has "ear com neg" written vertically on the side of the can. Not 
sure how that might relate to the terminals on the bottom.
It's mounted a little over an 8th of an inch above the board with some other 
small devices and device-board connections in that small space between the 
capacitor and the board. That made it a bit interesting to identify the 
capacitor terminals.
There are three spade connectors equidistantly spaced just inside the outer 
edge of the capacitor base and one longer wire connector more inboard.
With no power to the radio but the power switch "on" and the polarity switch 
set "up" all three spade connectors show a direct connection to the power 
lead and the wire connector shows a direct connection to the chassis. With 
the polarity switch flipped "down" the three spades now show a direct 
connection to the chassis and the wire connector shows a direct connection 
to the power lead.
Any additional help would be appreciated.

Thanks
John


----- Original Message ----- 
From: "Randall" <TR3driver at ca.rr.com>
To: "'John Finlayson'" <john_finlayson at telus.net>; <triumphs at autox.team.net>
Sent: Sunday, October 24, 2010 6:21 AM
Subject: RE: [TR] Triumph Bendix Radio


>
>
>> Does
>> anyone know which way the switch should be set for positive
>> ground, up or
>> down? There is no indication on the radio which way to set it
>> and I don't want
>> to apply power till I know which way to set it.
>
> One way to find out: Remove the covers and look for the main filter
> capacitor (usually pretty obvious, the largest round can-shaped thing) 
> which
> should have polarity markings on it.  With no power connected to the 
> radio,
> turn it's switch "on" and use an ohmmeter to determine which terminal of 
> the
> capacitor is connected directly (0 ohms) to either the chassis or the 
> power
> input lead.  Double-check by flipping the polarity switch and testing 
> again.
>
> If the "-" terminal is connected directly to the power input lead, or "+"
> directly to ground (the former is more likely); then the radio is 
> configured
> for positive ground.
>
> Randall