Re: Help! Rom3 goes silent.

[rubywand@aol.com]

In article <5d1bpf$hjk@gandalf.Advent.COM>, smcgroga@gandalf.Advent.COM
(Stephen McGrogan) writes:

>
>While inserting a mono remote speaker plug into my son's new
>(to us) IIgs Rom3, the sound was permanently reduced in volume.
>....


     Nathan Mates mentioned that your jack's leaf switches may not be
making good contact. This looks like a pretty good bet. (It would, also,
fit with Steven Bytnar's account of a sudden restoration of speaker
output.) 

     The explanation is that, with the leafs entirely removed, output
passes from capacitor SC6 through a 220 Ohm / 100 Ohm divider and L17 to
both the L and R jack contacts. This attenuated output is what you get at
the jack.

     Now add two leafs. When the plug is withdrawn, the L and R jack
contacts sprong inward. One contacts the leaf connected to the internal
Speaker lead; the other contacts the leaf connected directly to the output
at SC6. Since L and R are connected, this connects the unattenuated output
from SC6 to the internal speaker.
 
     If the leafs do not spring back and make good contact, your speaker
could be unconnected, poorly connected, and/or the direct output from SC6
could be missing. The 220 Ohm / 100 Ohm divider and L17 would pretty well
zonk sound output from an 8 Ohm speaker.

     The easiest test for the above is to plug in a stereo plug and run
the output from one of the center leads and GND to an amplifier or
headphones. If the output is a good, solid signal you can be pretty sure
that the problem with Speaker output is a bad contact in the jack.

     A squirt of contact cleaner plus in-out plugging may loosen things up
and restore decent contact. If this fixes things, it's surely a lot less
hassle than messing with SC6 or other surface mounted motherboard
components.



Rubywand