Hello everyone,
I just (almost) finished restoring Performa 630 which I got for €25 few years ago.
Previous owner presumably found it in some abandoned building, along with a painted black Mac 512K which I also got. He cleaned it a bit and removed the leaky battery, but didn't have the right monitor to test it.
It was in moderate cosmetic shape, front bezel had a nasty crack, also rear I/O cover (panel) was missing.
The included AppleDesign Keyboard had Esc missing. At least that key managed to escape (no pun intended).
Anyways, I tested the Performa when I first got it, just to see if it powers on, and it did, also there was a hard drive activity that stopped after a minute or two, so I presumed that it booted into the OS.
Few days ago, I dug it out again, and began testing, and found out:
- It boots into System 7.6.1 without problem
- Blue color is missing (everything is yellow)
- Sound not working
Logic board had some battery damage, but not too much.
So, I began testing, I got the pinout of the monitor connector and traced the blue signal to the interconnect board, and then to the logic board itself.
The diode reading was off, it read O.L., while other color signals read some low number (0.100 or so). I discovered that they all have 75 ohm resistors to ground. Now the only thing was to find those resistors, which took a while. I found that blue signal has a break in a via, which was then drilled out and jumped with a magnet wire. Also the oxidized resistors were cleaned and everything resoldered.
I now had proper image.
Next, sound took me more time. I began same thing, by tracing the signal from speaker back to the mainboard. The small PCB that contains speaker and monitor connectors actually has a preamp and speaker amp, so there is no direct connection from the logic board to the speaker. I then checked all the connections from the logic board multi-connector to the audio IC, and found no breaks. I checked all the things around that IC, and everything read fine.
Then I found a thread that someone had similar issues, and they were missing -5V. The audio IC requires two voltages, a positive +5V and a negative -5V.
Mine had +5V, but no -5V!
Minus 5V rail seemed fine, with no shorts. So I then began looking where that -5V is generated. There is a -12V that comes out of the power supply and is then regulated to -5V by a 7905 regulator. That regulator was also hit by battery electrolyte. Measuring around, it wasn't even getting the -12V, which was found quickly as there was an interrupted trace that goes to the capacitor (that I actually replaced before). Repairing that trace made no difference, but now the input to the regulator was proper -12V, but output was very high -9V, also ground was at -10V or so. With bit more measuring, I found both vias broken.
After repair, I got a nice stable -5V and loud sound!
I really hope there are no more broken vias / traces.
Next, I tackled the power supply, I was expecting lots of fishy smell and leaky capacitors, but it looked mint. I found just one 10uF 50V Nichicon that was leaking a bit. Others are all Nippon Chemi-Con SXE that I never found any to be leaking, so I left them all in. Also, I didn't have replacements for a full recap.
Now regarding the logic board recap on those machines. The forums say that the caps on those boards don't leak. Which I found 100% true, as none of the caps on my logic board was leaking. During repair / cleanup of the battery damaged area, I had to remove two capacitors, and there was no signs of leakage whatsoever underneath, also there were no fishy smells (that being the telltale sign of leaking electrolyte).
But in the end, I still had to recap the whole board!
Why?
Well, one of the two capacitors (47uF 16V) I removed initially had really high ESR, so I decided to check the others. ESR was so high on some, my meter didn't even register them - like the cap wasn't even there. I carefully desoldered each one and tested them again, they had ESR in range of 25-60 ohms, some even more than 100 ohms (I had to use a different meter), which is 100-200 times more than a good capacitor should have. All of them were 47uF 16V. The 3 others (100uF 6.3V) were much better in regards of ESR, but still were slowly getting there (I think they read about 2-3 ohms).
So, even if not leaking, they can be defective. I am amazed that the board worked that well with so many bad caps.
That's it, hope this helps someone.
I am still on a lookout for a front bezel and a rear I/O panel.
And of course, the escape key for that AppleDesign keyboard.
I just (almost) finished restoring Performa 630 which I got for €25 few years ago.
Previous owner presumably found it in some abandoned building, along with a painted black Mac 512K which I also got. He cleaned it a bit and removed the leaky battery, but didn't have the right monitor to test it.
It was in moderate cosmetic shape, front bezel had a nasty crack, also rear I/O cover (panel) was missing.
The included AppleDesign Keyboard had Esc missing. At least that key managed to escape (no pun intended).
Anyways, I tested the Performa when I first got it, just to see if it powers on, and it did, also there was a hard drive activity that stopped after a minute or two, so I presumed that it booted into the OS.
Few days ago, I dug it out again, and began testing, and found out:
- It boots into System 7.6.1 without problem
- Blue color is missing (everything is yellow)
- Sound not working
Logic board had some battery damage, but not too much.
So, I began testing, I got the pinout of the monitor connector and traced the blue signal to the interconnect board, and then to the logic board itself.
The diode reading was off, it read O.L., while other color signals read some low number (0.100 or so). I discovered that they all have 75 ohm resistors to ground. Now the only thing was to find those resistors, which took a while. I found that blue signal has a break in a via, which was then drilled out and jumped with a magnet wire. Also the oxidized resistors were cleaned and everything resoldered.
I now had proper image.
Next, sound took me more time. I began same thing, by tracing the signal from speaker back to the mainboard. The small PCB that contains speaker and monitor connectors actually has a preamp and speaker amp, so there is no direct connection from the logic board to the speaker. I then checked all the connections from the logic board multi-connector to the audio IC, and found no breaks. I checked all the things around that IC, and everything read fine.
Then I found a thread that someone had similar issues, and they were missing -5V. The audio IC requires two voltages, a positive +5V and a negative -5V.
Mine had +5V, but no -5V!
Minus 5V rail seemed fine, with no shorts. So I then began looking where that -5V is generated. There is a -12V that comes out of the power supply and is then regulated to -5V by a 7905 regulator. That regulator was also hit by battery electrolyte. Measuring around, it wasn't even getting the -12V, which was found quickly as there was an interrupted trace that goes to the capacitor (that I actually replaced before). Repairing that trace made no difference, but now the input to the regulator was proper -12V, but output was very high -9V, also ground was at -10V or so. With bit more measuring, I found both vias broken.
After repair, I got a nice stable -5V and loud sound!
I really hope there are no more broken vias / traces.
Next, I tackled the power supply, I was expecting lots of fishy smell and leaky capacitors, but it looked mint. I found just one 10uF 50V Nichicon that was leaking a bit. Others are all Nippon Chemi-Con SXE that I never found any to be leaking, so I left them all in. Also, I didn't have replacements for a full recap.
Now regarding the logic board recap on those machines. The forums say that the caps on those boards don't leak. Which I found 100% true, as none of the caps on my logic board was leaking. During repair / cleanup of the battery damaged area, I had to remove two capacitors, and there was no signs of leakage whatsoever underneath, also there were no fishy smells (that being the telltale sign of leaking electrolyte).
But in the end, I still had to recap the whole board!
Why?
Well, one of the two capacitors (47uF 16V) I removed initially had really high ESR, so I decided to check the others. ESR was so high on some, my meter didn't even register them - like the cap wasn't even there. I carefully desoldered each one and tested them again, they had ESR in range of 25-60 ohms, some even more than 100 ohms (I had to use a different meter), which is 100-200 times more than a good capacitor should have. All of them were 47uF 16V. The 3 others (100uF 6.3V) were much better in regards of ESR, but still were slowly getting there (I think they read about 2-3 ohms).
So, even if not leaking, they can be defective. I am amazed that the board worked that well with so many bad caps.
That's it, hope this helps someone.
I am still on a lookout for a front bezel and a rear I/O panel.
And of course, the escape key for that AppleDesign keyboard.
