Jump in the Delorean for this one. We're going back to the 80's here.
This has been an ongoing problem since I bought my Lisa two and a half years ago. When you turn it on you get a raster on the screen however you can get an image (albeit out of sync because it's non-standard composite) from the rear video port.
In the troubleshooting process I first was able to rule out both bad cabling between the card cage and the edge connector for the analog board. With a scope I can confirm that I am getting a TTL video signal as well. Through swapping parts with a friends Lisa I can confirm that the problem is on my analog board. With his installed I have no problems with video.
First I installed CR6 which was present on a friends card but not mine. That did not work and after testing it was removed again.
Second, I replaced the TDA 1170N along with the 7824CT (which I accidentally killed some how). This did not fix the problem either.
I have yet to replace any of the capacitors on the board yet (but if these were the cause I'd be first documented case). I'll order replacements for all of them next time I am off work. I'm getting pretty frustrated with this thing.
The vintage apple community is almost useless for repairs. All the recommendations so far was to find one on ebay and buy it but that's upwards of $150. I'm being somewhat forced to repair this. They normally do not break.
This has been an ongoing problem since I bought my Lisa two and a half years ago. When you turn it on you get a raster on the screen however you can get an image (albeit out of sync because it's non-standard composite) from the rear video port.
In the troubleshooting process I first was able to rule out both bad cabling between the card cage and the edge connector for the analog board. With a scope I can confirm that I am getting a TTL video signal as well. Through swapping parts with a friends Lisa I can confirm that the problem is on my analog board. With his installed I have no problems with video.
First I installed CR6 which was present on a friends card but not mine. That did not work and after testing it was removed again.
Second, I replaced the TDA 1170N along with the 7824CT (which I accidentally killed some how). This did not fix the problem either.
I have yet to replace any of the capacitors on the board yet (but if these were the cause I'd be first documented case). I'll order replacements for all of them next time I am off work. I'm getting pretty frustrated with this thing.
The vintage apple community is almost useless for repairs. All the recommendations so far was to find one on ebay and buy it but that's upwards of $150. I'm being somewhat forced to repair this. They normally do not break.
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