Performa 6200 — ADB power-on works but no keyboard/mouse input

[mndeaves]

Hi all,

I've got a Performa 6200 where the keyboard power-on button works perfectly every time — Mac chimes and boots to the desktop. But once booted, there's zero response from keyboard or mouse. No key presses, no mouse movement. It was working perfectly for months since I replaced the power supply.

I've tried multiple known-working ADB keyboards and mice, same result. Pressed the reset button, pulled and removed/reconnected the battery (a new one soldered to the original header), no change. Board looks clean with no visible cap leakage or corrosion.

Multimeter readings on the ADB port while powered on and booted:

• GND to +5V pin: 4.9V
• GND to DATA pin: 4.9V

So I think the port looks electrically healthy. PSW line obviously works since the keyboard powers on the machine. From googling it might be something about a Cuda chip? I didn't think to remove the stick on heat sinks from this machine but wondered if they might do more harm than good. Is there anything else I could try? The machine works perfectly other than this (luckily launches the Retro68 Application Launcher and Rumpus FTP on boot) and it seemed to happen overnight while I left it copying files to the drive.

Few shots included, can't see any caps that look bad, none have been replaced as far as I know.

 

[Phipli]

ADB power on is a separate thing to data - it has its own pin. There is no commonality so one working is unrelated to the other.

First thing I'd suspect is the port. Check for dry solder joints and spray deoxit in the port.

Everything after that will be more difficult, and your board does look like it is reasonable condition regarding capacitors.

 

[mndeaves]

ADB power on is a separate thing to data - it has its own pin. There is no commonality so one working is unrelated to the other.

First thing I'd suspect is the port. Check for dry solder joints and spray deoxit in the port.

Everything after that will be more difficult, and your board does look like it is reasonable condition regarding capacitors.

So lifting up that RF shield over the port connectors and checking there for solder cracks? I'll get some deoxit as well. Thanks!

 

[Phipli]

So lifting up that RF shield over the port connectors and checking there for solder cracks?

They'll be on the underside of the board, I don't think the shield needs removing, but I could be wrong.

Dry / cracked solder joints can be hard to see - you might see it by wiggling the port a little to see if part of the solder moves separately to the board, but really it's easier to just reflow it with a dab of no clean flux and a touch of a soldering iron.

 

[mndeaves]

They'll be on the underside of the board, I don't think the shield needs removing, but I could be wrong.

Dry / cracked solder joints can be hard to see - you might see it by wiggling the port a little to see if part of the solder moves separately to the board, but really it's easier to just reflow it with a dab of no clean flux and a touch of a soldering iron.

So I looked under the board, I can re-flow the joints on the first picture... but then on deeper inspection I noticed something that doesn't look very.. factory like with R85 reckon that looks..normal?

 

[mndeaves]

Gutted. Reflowing those 4 joints didn't solve the problem