68kMLA Classic Interface
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| Click here to select a new forum. | | LC575 Analog Board failure | Posted by: CharlesT on 2017-03-09 18:51:41
Hi all. Was wondering if anyone has ever made the mistake of powering up one of these puppies leaving the anode cap disconnected by mistake? I did this recently following a recap. Powered it up for the first time, computer booted and made all the right noises but display was dark. After thinking dark thoughts about my soldering technique I happened to notice the anode cap hanging off to the side. So I plugged it back in and powered up. Nothing. Got the degauss little buzz but that was all.
I've got lots of electronics experience but very little with CRTs, so their peculiarities are new to me. Is it possible to pop the HOT when doing this?
| Posted by: techknight on 2017-03-10 17:38:22
You probably took out the horizontal output transistor.
| Posted by: CharlesT on 2017-03-11 09:36:06
Thank you techknight, I'll pull that today and check it out. Sure wish Apple would release schematics for this stuff. By the way, anyone interested in CRT monitors should check out "https://www.repairfaq.org/REPAIR/F_monfaq.html".Really good info. Between that and pulling all the data sheets for the part numbers I can make out I think I'm starting to get a little bit of a clue as to how this thing is put together.
SlateBlue is sending me an a/b out of a 550 soon, that would let me look at signals on a good board as a reference.
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