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Apple M1296 Drawings

Gary C

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Joined
May 26, 2018
Messages
2,201
Location
Lancashire, UK
Anyone have circuit diagrams of the Apple Mac II monitor M1296 ?

I have two to fix and have been scouring the ether looking for them with no success.

Cheers.
 

Gary C

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Joined
May 26, 2018
Messages
2,201
Location
Lancashire, UK
So

First observation is no glow in the neck (can be hard to see, but I can see it fine on the working one), but that I have 24KV under the cap, so flybacks occuring.

Managed to trace the Tubes model number (AT12A9SLB22) to a website listing adapters to fit to a tube regenerator. Tracing adapter A8 gave me the following neck pinout for Base type B10-277
Then with much searching (amazing how hard it is to find CRT info) to a pinout of

5 G1
6 Green K
7 G2
8 Red K
9 Heater 2
10 Heater 1
11 Blue K
12 G4

So heater checked and loop resistance is fine.

Checking on the flyback transformer 334P0311 gives me a HR 46097 and the circuit diagram checked against the pins, getting a 20V peak waveform on the heater supply pin 5. Loop checked to the neck socket and seems ok but a small resistance. Gave everything a clean and reassembled.
Got the glow back :)
Turned up brightness and the first 1/3rd of the picture is stretched, then a bright line, then a wibbly but otherwise normal picture.

While its not mine, it appears exactly like this one

DeadRGB.jpg


Everyone that I have researched has then just done a capacitor replacement, mainly C418, so without a circuit diagram, I am forced into almost random 'recapping' (ooh I hate that phrase). At least it will keep me busy.
 

Gary C

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Messages
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So a bunch of electrolytics replaced. There was a lot of leakage around those directly under the tube so at least one has failed.

All plugged together and now I get a nice, stable image.

There is a scratch on the CRT though :( will try the car windscreen scratch fillers. Will be interesting to see if they work.
 

Gary C

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Joined
May 26, 2018
Messages
2,201
Location
Lancashire, UK
Second unit just needed adjustments. Was wildly out on horizontal and vertical syncs and I think someone had been trying to get it to work but hadn't gone through it step by step, though it was odd in that a simple tweak of horizontal sync would make the picture stable but it wouldn't resync when it was turned off then on.
Followed the repair guide and now looking good :)

So thats two working monitors for my LC & IICi.
 
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