Author Topic: help with regulator  (Read 440 times)

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Offline vixoTopic starter

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help with regulator
« on: February 27, 2020, 04:54:22 pm »
im fixing an old piece of musical equipment for a friend. I have the schematic, but it turns out the schematic doesn't follow what I have in front of me. The device is powered by two 9volt batteries in series, but the 'ground'  is derived from regulators. I'm seeing that the positive power rail is very close to the negative, so I investigated the power section and disconnected the power from the main circuit to make sure nothing in the circuit was affecting it - no change - so I started looking at the circuit itself and discovered that it's not the same as the schematic but actually has two PNP 2N3906's (figure 1) instead of the schematic (figure2) MPSA14. This doesn't make sense to me - shouldn't that type of darlington pair be used *the other way up*? I can't understand how it is supposed to work. To add more confusion, in simulation (figure 1) it seems to work fine, but in the piece of equipment AND when i breadboard it, it does the same thing - the rails are about 0.2 volts away from each other.

can anyone shed some light on this? Should this work, or what??

this is the entire schematic that I have :
http://clacktronics.co.uk/research/drumlab/star-synare-3/Clacktronics_Star_Synare_Schematic.gif
 


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