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DE power supply help needed - no 5 volts

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k...@evolve-studios.net

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Nov 18, 2012, 10:28:43 AM11/18/12
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Im not getting 5 volts on the power supply of my Jurassic Park - game won't boot.

Here is what I know.
1. Swapped boards with another DE game and the game works so I know its an issue with my power supply board.

2. I changed
bridge rectifier (DB1, CM3501),
C2 (100uf 25v),
C3 (47uf 63V),
C7 (330uf 25V),
LM723 voltage regulator,
TR5 (2N6057)
C1 (1000uf 25V)

Testing various points on the board I notice I get 13v going into TR5 but nothing coming out either the white or yellow wires - should I get a reading here? Ive swappwd tr5 twice - From this point my electronics knowledge just isn't there - any suggestions how to further trouble shoot. am I missing something obvious?

Thanks guys

KenLayton

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Nov 18, 2012, 12:14:21 PM11/18/12
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Cracked fuse clips?

Blown fuse?

Bad solder joints?

Bad connectors?


--
KenLayton
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k...@evolve-studios.net

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Nov 18, 2012, 12:27:17 PM11/18/12
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On Sunday, November 18, 2012 12:16:04 PM UTC-5, Ken Layton wrote:
> Cracked fuse clips?
>
>
>
> Blown fuse?
>
>
>
> Bad solder joints?
>
>
>
> Bad connectors?

Hey Ken thanks for the reply, I have gone over the board several times and reflowed almost every solder joint, fuse holder etc.

Im getting voltage up to the point of the TR5 on the one side, Im not exactly sure how that regulator works so thats where Im stuck.

GPE

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Nov 18, 2012, 3:32:07 PM11/18/12
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>
> Hey Ken thanks for the reply, I have gone over the board several times
> and reflowed almost every solder joint, fuse holder etc.
> Im getting voltage up to the point of the TR5 on the one side, Im not
> exactly sure how that regulator works so thats where Im stuck.

Old Data East supply uses a 'series pass transistor' type regulator -- the
2N6057 does the regulation and the LM723 controls it.
First thing in trouble shooting these - make sure you have voltages coming
into the regulator circuit.

For starters, with a meter grounded to TP2 --
1 -- measure the voltage at the collector of TR5 (2N6057). Collector is the
case.
2 -- measure voltage at pin 12 of IC1... what do you get? (should be roughly
double)

Ed


k...@evolve-studios.net

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Nov 18, 2012, 4:59:19 PM11/18/12
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On the collector I get 13.3volts on ic1 pin 12 I get nothing

k...@evolve-studios.net

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Nov 18, 2012, 6:42:19 PM11/18/12
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Fixed thanks everyone - ended up being a bad through hole trace on c2 that is a trace on top of the board going to a diode- made little solder bridge - boom fired right up...
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