I just thought it could be useful to collect information on this regulator board since it can be a little bit tricky and also is a slightly uncommon design for being a switch mode PSU in that it lacks the standard control circuitry like a 3524 or similar chip.
Myself have several of these in various boxes. I found that two of them differed quite significantly and tried to nail down the differences. I made this picture.
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The paper schematics I have is CS rev U while the one on bitsavers is CS rev AB.
The differences I discovered:
1. They have put two 1u capacitors on the input connector in the later version.
2. They have removed C16, C10, C13 in the later version!
3. They put FET instead of a transistor stage on the AC LO and DC LO signals.
4. C9 is a tantalum in the later version.
5. Someone might have used a wrong value for C16. Both schematics says 100uF. But the earlier version board has a 22 uF tantalum capacitor.
6. The -15V supply output filtering is a Nichicon 4500uF capacitor instead of the 3000uF. I am not sure it has been replaced or is original. I cannot tell what the date code is: "70819"
Michael: When you did your Spice model, which version did you model? Is there other interesting findings you can report?
Regarding the capacitors I have been trying to test those. My capacitance meeter can only do up to 20000 uF. And it says out of range so I assume they are at least 20000 uF. I was alos measuring the output filtering capacitors and they measured almost nominal values and ESR at 0.2 ohm.
Myself have several of these in various boxes. I found that two of them differed quite significantly and tried to nail down the differences. I made this picture.
The paper schematics I have is CS rev U while the one on bitsavers is CS rev AB.
The differences I discovered:
1. They have put two 1u capacitors on the input connector in the later version.
2. They have removed C16, C10, C13 in the later version!
3. They put FET instead of a transistor stage on the AC LO and DC LO signals.
4. C9 is a tantalum in the later version.
5. Someone might have used a wrong value for C16. Both schematics says 100uF. But the earlier version board has a 22 uF tantalum capacitor.
6. The -15V supply output filtering is a Nichicon 4500uF capacitor instead of the 3000uF. I am not sure it has been replaced or is original. I cannot tell what the date code is: "70819"
Michael: When you did your Spice model, which version did you model? Is there other interesting findings you can report?
Regarding the capacitors I have been trying to test those. My capacitance meeter can only do up to 20000 uF. And it says out of range so I assume they are at least 20000 uF. I was alos measuring the output filtering capacitors and they measured almost nominal values and ESR at 0.2 ohm.