Programmer's Switch on Mac Portable not working

[NJRoadfan]

Any item why?

I installed MacsBug 6.5.3 to test it out. The debugger installs on boot, but pressing the Programmer's Switch does nothing.

 

[nvdeynde]

These switches often go bad. Replace it: anyone from another Mac Portable or Compact Mac will do as they are identical.

I don't know if new switches like these are still for sale.

 

[RickNel]

I'd first be checking whether the physical contact-switch is the problem. They typically contain a tiny spring-metal dome that can get deformed or broken in some circumstances, or the action can be blocked by a speck of dirt of some kind. First check the on-off operation with the continuity tester on your multimeter, and if it fails look for a mechanical reason. If it needs to be replaced, the actual switch mechanism is quite generic, but it is also possible to wire in a non-standard contact switch if you have to.

IIRC there is also an isolation capacitor near that switch, which I would look at next if the switch appears to operate correctly.

Deeper than that... :-/

Rick

 

[NJRoadfan]

The isolation capacitor was replaced along with the rest of the caps. The reset switch works fine so I found it odd that the programmer's switch didn't. I'll have to check it again to see if its closing.

 

[NJRoadfan]

I can confirm the switch contacts are working. Continuity test confirms its closing when pressed.

 

[nvdeynde]

Are the 2x small SMD capacitors near the switches soldered well: test them and check for lifted traces as well. Otherwise check the circuit from the switch to the next component for broken traces.

Anyway it's not really a big deal that the programmer switch doesn't work as you don't need them when the logic board has been recapped.

I never had to press the reset/interrupt switches again after recapping my Mac portables while before it was always a pain and guess after how many times it would start...

 

[NJRoadfan]

The reset switch works fine. Testing the programmer's switch isolation cap, I get continuity from the negative terminal to one of the switch terminals. The positive terminal gets continuity to a pin on the "MISC GLU" chip as expected. When power is completely removed from the machine, I have to power cycle it for a good minute to reset the PMU and clear the instant sad mac despite being recapped.

 

[nvdeynde]

When power is completely removed from the machine, I have to power cycle it for a good minute to reset the PMU and clear the instant sad mac despite being recapped

How do you power cycle it ? If you have a working battery this shouldn't be necessary as when you remove all power, the capacitors drain quickly and then the PMU is automatically reset in a matter of seconds. You have a rebuild battery I assume ?

What sad mac code do you get ?

I use my Mac Portables regularly but never leave the main battery installed. However they always power on immediately after inserting the battery and pressing the keyboard.

I have seen Mac Portables from fellow collectors that used the Mac Portable without rebuild battery on a heavy DC PSU and got the logic board damaged this way ( PMU errors, unstable, often not willing to power on,... ).

We also never know what previous owners did with the computers before we got them...

 

[NJRoadfan]

I'm using a rebuilt battery and the stock 1.5A power supply. Errors are usually 0000 13xx or 0000 17xx, neither of which actually come up as valid codes. Once the PMU finally resets, I don't have any problems until power is removed again by taking out the battery.