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Donner 3500 Tube Layout

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  by Bill Degnan - 06/18/2009 22:52
There are 6 control boards in the Donner 3500, each has a set of tubes. This weekend I tested every one of the tubes, they all work. I used a Heathkit tube tester.

Voltage Regulator card for the Donner 3500 analog computer. This card is inserted into the left most slot on the blue ribbon receptical bus back plane.


Viewing from the back of the unit with the door open:

1) left-most card is a voltage regulator, tubes from left to right:
6BR8
12AX7
12AX7
5651
CK-7044
12BH7A

2) The remaining 5 cards are the same, the tubes from left to right are:

6BR8
ECC 83 / 12AX7
ECC 83 / 12AX7
- NOT A TUBE (It's a relay)
ECC 83 / 12AX7
6BR8

3) There are two tubes attached to the chassis to the right of the 6th card. The tubes in this space are both marked OB2

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