I purchased a Performa 600 on purpose. Why would I do this? Well, it contained a Sonnet Presto 040 accelerator card.
In what would be the start of a series of disappointments for this purchase, the accelerator card does not include the 128K cache. Bummer.
Next, the computer would not power on. This was surprising, since I am accustomed to the Centris 650 line always working. But, the Performa 600, IIvi, and IIvx have leaky surface mount capacitors. So, I began recapping the board. Can you spot the power-on problem in the image below?
In the image above, take a close look at the three pins of the EGRET that are nearest the leaky C21 capacitor. Notice the green?
In the image below, when I tried cleaning off the green corrosion, the chip leg fell off. It was only held together by crud. The EGRET is responsible for powering on the computer.
This gave me the opportunity to try a trick that I've seen performed by repair masters. I ground off a portion of the top of the EGRET chip to expose where the broken leg would have entered. I used a Dremel rotary tool with a grinding bit. I could not find documentation on what would be the most gentle bit. So, I proceeded slowly and got lucky.
I then bent a bare wire from the pad, across the exposed internal connection, and over the top of the chip. I taped the wire in place and applied a lot of flux. I soldered the pad first. Then, I hit the internal connection with a lot of solder. It seems really secure.
This may be too delicate for the average repair person. There is a surprising alternative. It turns out the the 600/IIvx/IIvi use the same EGRET as the Macintosh IIsi. Below, on the left, see the repair EGRET. On the right, a photo from a IIsi. Same part number. The dates (9234, 9224) are even close!
I'm not sure if it is a sin to sacrifice a IIsi to fix a IIvi. However, if the IIsi is beyond repair, just remember it can be a donor.
After recapping, cleaning, as well as resoldering and repairing the EGRET, my Performa 600 powered on! Yea!
BAD VIDEO
Yet again, I was disappointed in this purchase as the screen colors were all messed up. At first I thought it was a loose connection or incompatible monitor.
Then, I suspected maybe the blue video line was broken. But, looking at the clut in the Monitors control panel, I can see a variety of colors, including red, green, blue, and white.
The Ariel chip provides video on these computers. That chip, and the video connector, are far away from leaky capacitors. How could this be bad? I tried reseating the VRAM without improvement.
My eyes followed the traces from the Ariel chip to a different quadrant of the board. Wouldn't you know it! Leakage from the original C35 and C34 capacitors corroded a trace. I don't know how I missed that.
Shaving off the solder mask and soldering a bare wire bypassed the damaged areas. The video is fixed!
ADDING CACHE
The Performa 600 is similar to the Macintosh IIvx, except the Performa lacks the 32K cache and the FPU. @GiGaBiTe worked out how to add cache to the IIvi and Performa 600. See the details here: https://tinkerdifferent.com/threads/performa-600-cache-mod-iivx-pictures-needed.5158/
If you're lucky enough that Apple populated U46, U49, and U53, then you can add cache memory. You need to add four SRAM chips, two TAGRAM chips, as well as some resistors and capacitors to the back of the board. Like @GiGaBiTe I found hand-soldering the SOJ packages to be error prone. My first pass ended with a lot of legs floating above their pads, and several shorts between pins due to solder blobs. Even after several rounds of inspecting and fixing, I still had a short and lifted leg that took some time to find. Until it was correct, sometimes the computer would power on with a blank white screen but no startup sound. Sometimes it would play the sound but not proceed forward.
In the end, I got the cache working. With the addition of an FPU, the Performa 600 has the same performance as the IIvx. That's not saying much. Nevertheless.
Despite the upgrades, it still identifies as a Performa 600, which is sorta strange and fun.
- David
In what would be the start of a series of disappointments for this purchase, the accelerator card does not include the 128K cache. Bummer.
Next, the computer would not power on. This was surprising, since I am accustomed to the Centris 650 line always working. But, the Performa 600, IIvi, and IIvx have leaky surface mount capacitors. So, I began recapping the board. Can you spot the power-on problem in the image below?
In the image above, take a close look at the three pins of the EGRET that are nearest the leaky C21 capacitor. Notice the green?
In the image below, when I tried cleaning off the green corrosion, the chip leg fell off. It was only held together by crud. The EGRET is responsible for powering on the computer.
This gave me the opportunity to try a trick that I've seen performed by repair masters. I ground off a portion of the top of the EGRET chip to expose where the broken leg would have entered. I used a Dremel rotary tool with a grinding bit. I could not find documentation on what would be the most gentle bit. So, I proceeded slowly and got lucky.
I then bent a bare wire from the pad, across the exposed internal connection, and over the top of the chip. I taped the wire in place and applied a lot of flux. I soldered the pad first. Then, I hit the internal connection with a lot of solder. It seems really secure.
This may be too delicate for the average repair person. There is a surprising alternative. It turns out the the 600/IIvx/IIvi use the same EGRET as the Macintosh IIsi. Below, on the left, see the repair EGRET. On the right, a photo from a IIsi. Same part number. The dates (9234, 9224) are even close!
I'm not sure if it is a sin to sacrifice a IIsi to fix a IIvi. However, if the IIsi is beyond repair, just remember it can be a donor.
After recapping, cleaning, as well as resoldering and repairing the EGRET, my Performa 600 powered on! Yea!
BAD VIDEO
Yet again, I was disappointed in this purchase as the screen colors were all messed up. At first I thought it was a loose connection or incompatible monitor.
Then, I suspected maybe the blue video line was broken. But, looking at the clut in the Monitors control panel, I can see a variety of colors, including red, green, blue, and white.
The Ariel chip provides video on these computers. That chip, and the video connector, are far away from leaky capacitors. How could this be bad? I tried reseating the VRAM without improvement.
My eyes followed the traces from the Ariel chip to a different quadrant of the board. Wouldn't you know it! Leakage from the original C35 and C34 capacitors corroded a trace. I don't know how I missed that.
Shaving off the solder mask and soldering a bare wire bypassed the damaged areas. The video is fixed!
ADDING CACHE
The Performa 600 is similar to the Macintosh IIvx, except the Performa lacks the 32K cache and the FPU. @GiGaBiTe worked out how to add cache to the IIvi and Performa 600. See the details here: https://tinkerdifferent.com/threads/performa-600-cache-mod-iivx-pictures-needed.5158/
If you're lucky enough that Apple populated U46, U49, and U53, then you can add cache memory. You need to add four SRAM chips, two TAGRAM chips, as well as some resistors and capacitors to the back of the board. Like @GiGaBiTe I found hand-soldering the SOJ packages to be error prone. My first pass ended with a lot of legs floating above their pads, and several shorts between pins due to solder blobs. Even after several rounds of inspecting and fixing, I still had a short and lifted leg that took some time to find. Until it was correct, sometimes the computer would power on with a blank white screen but no startup sound. Sometimes it would play the sound but not proceed forward.
In the end, I got the cache working. With the addition of an FPU, the Performa 600 has the same performance as the IIvx. That's not saying much. Nevertheless.
Despite the upgrades, it still identifies as a Performa 600, which is sorta strange and fun.
- David
