[Collins] 75S-3C power transformer

[Dave Brown]

Thanks for the comments Jerry.
Wire colour codes make sense-although a 'translation' table somewhere in the
handbook would have been useful if they were going to the trouble of putting
the codes in the schematic.

Consistent orientation and tag use of TB2 would have helped a lot in
identifying what is connected to what, but I guess wire colour codes may be
as useful now I know what they are.

 The 230 volt transformer is part numbered (Collins) 662 0250 010 and is
also marked Freed p/n 41628- I would have thought that wire colour codes
would have been consistent on both.  Would this transformer have been
factory fitted? Terminations look undisturbed and original which is why I'm
reluctant to touch 'em.

Anyway I'll check the green transformer wire again- it tests as being very
low resistance to the correct pin (2) on the power connector and about 23
ohms to the black wire, but I may just have to take a wire or two off TB2
(which is what I was hoping to avoid) to be sure. It was the green colour
that concerned me, despite the resistance measurements.

73
Dave, ZL3FJ

----- Original Message ----- 
From: "Dr. Gerald Johnson" <geraldj at ispwest.com>
To: <tractorb at ihug.co.nz>
Cc: <Collins at mailman.qth.net>
Sent: Tuesday, August 03, 2004 3:09 AM
Subject: Re: [Collins] 75S-3C power transformer


> I don't remember the DA designation for the wire type. A full Collins
> wire designation would have been something like A22PB91 for a
> pvc insulated wire with color code 91 (white with brown stripe). The
> DAS and DA may have applied to some other insulating type or
> thickness. I'm sure the numbers apply to the wire color codes. 1
> being brown, 0 being black, 9 being white, etc. So the DASJ91
> would be white with a brown stripe. DAS912 would be white with
> brown and red stripes (brown stripe wider than the red stripe).
> DA93 would be white with orange stripe, DA902  would be white
> with black and red stripes, DA903 white with black and orange
> stripes, DA905 white with black and green stripes, DA906 white with
> black and blue stripes, DASJ5 would be solid green. DA95 white
> with green stripe.
>
> The transformers themselves have standard RET MA color coding
> for their leads. Primaries typically black and black/white alternating
> for single voltage. High voltage secondary red or red/yellow for the
> center tap. 6 volt heater green, sometimes with a green and a
> second color for the second lead. Green should have never been
> a line color from the transformer, line leads should be black with
> other colors in alternating patterns, but always predominating
> black.
>
> The turret terminal labels (these were standard turrets from Vector
> Cop) may have been significant but probably were only shown to
> the assembly line workers in their detailed production drawings.
> Then again maybe only the position in the radio was significant and
> the letters were ignored. I don't think they had any automatic way
> of orienting the A terminal in a certain direction so control of which
> lug was used for a particular circuit may have depend on which
> way the lug pointed, not which letter was next to it.
>
> 73, Jerry, K0CQ, Technical Advisor to the CRA
>
> -- 
> Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
> Reproduction by permission only.
>
>
>
>
>