SE/30 startup sound issue

[rickrob]

I recapped my SE/30 recently and all was well, until I noticed that after leaving the machine off overnight there was no startup sound on power up. Once the machine powers up- even for just a couple of seconds it comes back. If I power off after two seconds, wait a few seconds and power on, it's OK. 

I'm wondering if one of the caps I used (electrolytics) is bad.  Does anyone have a suggestion on what I could look for?

I think it's C6 that's in the sound circuit, may be I should replace that one again?

I'm not real happy with the electrolytics-- thinking about buying one of the tantalum cap sets here and redoing it.

Thanks

 

[trag]

It sounds like there is a lot of resistance in one of your circuits with the capacitor.  This leads to lower than normal current, and a very long delay for the capacitor to charge up.   Of course. I could be completely wrong.

Anyway, high resistance could be a faulty cap, but seems more to suggest a poor or incomplete solder joint somewhere -- or possibly a damaged trace/via from previous capacitor leakage.

 

[Elfen]

Also...

Look at the traces, especially those around the caps. See if there is a silver spot on the trace that goes to the other side, that's a jumper or connecting spot to the trace on top with one at the bottom of the board. What color is it? It should be bright silver. If not then the joint corroded. You will need to be very careful and gentle in cleaning up that joint as to not kill it or short it out.

With a desoldering wick and iron or a desoldering iron with suction, only apply heat to the joint to desolder it. Do not press the tip of the iron onto the board or the wick, or you will damage the board if you do. You may have to apply some flux and fresh solder to the joint to get it to melt and then get it all out until there is a nice clean hole (as much as possible).

Wipe down the clean joint to remove the dirt and burnt flux off it, use acetone and alcohol on a q-tip for this.

Then apply a little flux to both sides of the board. Then solder the hole shut. It will require some solder, more than you think as you are filling up that hole again and reconnecting the two joints together again.

Inspect your work and see if it's a nice shiny solder joint. Go and do the same to the ones next to it that you find. Repeat as needed. Then clean your board off with acetone and alcohol to remove the burnt flux crud.

 

[rickrob]

Thanks everone-- I'll look at all the traces again and recheck my solder joints.  It's working fine again today...

 

[uniserver]

could you do me a favor and take a Higher Resolution, Decently lit picture of your main board. maybe we will see something.