SB303 all lamps went out???

[Marshall M. Dues]

Hello, Dan and All,

The pilot lamps are 3 each #47 lamps in a series string and fed by a
50 ohm, 5 watt resistor from one of the red secondary wires of
transformer T-701.  If all the lamps are out, I would suggest checking
for an open R-701 resistor, a 5 watt, 50 ohm sand box type resistor,
part number 3-17-5. This resistor is mounted under the chassis from
terminal #3 of a 3-term strip at AZ to terminal #5 of a 5-term strip
at AY. Also, check for the presence of 50 volts AC from the two large
red wires coming from the T-701 transformer through grommeted hole AF
to terminals 1 and 3 of the 3-term strip.  These lamps are in a series
string just like Christmas tree lights - if one of them is burned out,
the whole string will be inop. Than is probably your problem. Also,
check for an open ground on the end of the string of lamps.

Hope this steers you in the right direction.

Best regards,

Marshall Dues - WB5MYO
Katy, Texas




Dan Pividal N4VET wrote:
>
> I have an SB303 which is working fine but all the lamps in the radio went
> out.
> What do I look for to get them working again?
> Have any of you had this happen?
> snipped ...

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