Macintosh IIsi - speaker very quiet

[egrath]

Hi,

the speaker of my IIsi shows a interesting behavior: It's very quiet, no matter which level I set in the control panel. Essentially there are only two states: very quiet for all levels >0, and completely silent (as expected) for 0.

Any ideas what could be the reason for this or which component could be defective and needs to be replaced?

With kind regards,
Egon

 

[robin-fo]

Clean the speaker contacts

 

[egrath]

Thanks, I try that. But just out of curiosity, if the contacts are corroded and therefore have a higher resistance, shouldn't there be more levels than just quiet and silent?

 

[egrath]

Tried the following now:
1. Cleaned the contacts on both, the logic board and the speaker assembly unit ==> no change in behavior (just two levels: Quiet and Silent)
2. Replaced the entire speaker unit with a known good one ==> no change
So my assumption is that something on the logic board is broken. Any ideas on what to check next?

 

[robin-fo]

Check for capacitor juice damage around C9-C11. Do you have the same issues when listening through headphones?

 

[egrath]

The area around the capacitors looks good - the board has been recapped before the caps became leaky:

With headphones attached, at least the different volumes level work as expected. However, it's slightly noise, somewhat like the noise you hear when making a mobile phone call.