[Kenwood] TS-850S DC-DC Converter Board

[GALE STEWARD]

Yes, I noted the "off the board" components. What ever
failures that have happened with this board,
apparently replacing it solved the problem which would
rule out the external components. The solder issue is
certainly a possiblity, however. That's why I'm
interested in finding out if anyone actually did some
troubleshooting of a failed board. We will see what
info surfaces.

73, Stew K3ND




--- "Dr. Gerald N. Johnson, electrical engineer"
<geraldj@isunet.net> wrote:
> There are a couple (I presume aluminum)
> electrolytics that aren't on the
> DC-DC board but essential to its functioning that
> I'd be highly
> suspicious of. The miniature aluminum electrolytic
> was never really
> great to begin with and ages rapidly. Its fairly
> heat sensitive and very
> intolerant of long storage without applied voltage.
> When I check "new"
> ones for leakage and power factor, I reject most.
> And lately the buzz in
> the computer industry is that many coming out of
> China are blowing up on
> motherboards with the first time power was applied.
> Apparently those
> with the best prices haven't been formed or have
> used poor quality
> materials. Perhaps being built in a chicken house
> has then contaminated
> with eggshells.
> 
> 12 volts in, -6 volts out is a natural application
> for the 7660 and its
> many derivatives from Maxim, TI, Analog Devices, or
> Linear Technology.
> With better regulation that the zener diode provides
> and more energy
> efficient, though one should watch out for RF noise.
> 
> On the surface mount board, the failure could as
> easily be a bad solder
> connection as component failure.
> 
> 73, Jerry, K0CQ
> -- 
> Entire content copyright Dr. Gerald N. Johnson,
> electrical engineer.
> Reproduction by permission only.


__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
http://mailplus.yahoo.com