68kMLA Classic Interface

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SE/30 12v supply issue
Posted by: kingchops on 2015-10-24 19:04:22
I did my first re-cap yesterday on my SE/30.  I'm glad to say it went well.  I wasn't getting any sound before, now I get clear and loud sound through the headphone jack.  But unfortunately I'm not getting sound through the internal speaker.  I plugged in another internal speaker (smaller), and I get faint sound through that.  So I checked the voltages at the plug that connects to the logic board (with the plug removed),  I'm getting -11.1v and +11.62v on pins 7 and 8 on the connector.  The 5v supplies are fine.  So I suspect that there's some issue on my analog board or power supply. 

The SE/30 generally runs great, screen is good, SCSI port works fine, internal drives work fine.  The only things I have issues with are the internal sound and the external drive connector.  Whenever I connect a drive or Floppy Emu to the external connector it's very flaky.  Not sure why the internal drives are not affected.  Would a recap of the power supply be recommended to fix the 12v supplies?
Posted by: takimoto on 2015-10-25 08:36:39
Caps in PSU can leak like this.

1098365_596772083707616_1372614101_n.jpg

45260_596772127040945_1806093451_n.jpg

So you should check!(Maybe only caps in low voltage part are leaky.)
Posted by: unity on 2015-10-25 11:31:58
^ Ditto.

The SE and SE/30 supplies have a reputation of being very solid when it comes to power supplies. But I think their time has come. I am seeing more and more cases of SE power supplies becoming defective.
Posted by: techknight on 2015-10-25 13:26:44
Well thats with anything at that age, these days. 

I am working on a mac M1296 monitor, which pairs up with the LC series. Same deal, some of the caps are leaking causing picture distortion, and ultimately horizontal output transistor failure. 
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