(Topic ID: 257395)

PSU5 LM323K Replacement

By wombat

4 years ago


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  • 16 posts
  • 11 Pinsiders participating
  • Latest reply 4 years ago by Crash
  • Topic is favorited by 2 Pinsiders

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    #7 4 years ago
    Quoted from ChrisHibler:

    I wouldn’t.
    1. The heat isn’t an issue. That’s what the big heat sink is for.
    2. The regulator is working. Why mess with it?
    3. The ez part causes the sound board to emit a machine gun sound on power down. It’s annoying.
    4. The LM323K isn’t a significant reason for resets. Connectors cause far more resets than the LM323K.

    Chris Hibler - CARGPB #31
    Http://chrishiblerpinball.com/contact
    http://www.PinWiki.com/ - The new place for pinball repair info

    1. Heat does cause damage to the boards over time and dry solder joints. It also puts more load on the 12v power supply including the connectors and board components in that chain. The waste heat is created as part of the original linear regulator's design to lower the output voltage to 5v.

    2. These regulators do cause intermittent issues. For example, I re-capped my power supply in Police Force and am still only getting 4.95v out of it. This is with no 5v loads connected. As a result the game often does not boot.

    3. Simply a personal preference vs. how good the game functions after upgrading the regulator.

    4. It is often not, but with these parts often times being over 30 years old, that statistic is changing.

    #13 4 years ago

    I'm having an issue with mine in my Police Force. It doesn't seem to be switching/regulating properly and outputs way too high. Fortunately I decided to test this before connecting any of the boards. Before I swapped this the game booted once, but did not boot subsequent times. I wanted to try this and here is what I'm seeing. I have it installed with alligator leads connected to a 555 lamp.

    DSC_0013 (resized).jpgDSC_0013 (resized).jpg

    I'm getting this on the 5v test point:

    DSC_0012 (resized).JPGDSC_0012 (resized).JPG

    So I decided to check the input vs. output test points on the PSU5.

    Input:

    DSC_0016 (resized).JPGDSC_0016 (resized).JPG
    DSC_0017 (resized).JPGDSC_0017 (resized).JPG

    Output:

    DSC_0014 (resized).JPGDSC_0014 (resized).JPG
    DSC_0015 (resized).JPGDSC_0015 (resized).JPG

    I took another one of these and fed it 13.5v from my bench power supply. I hooked up the lamp and it's now getting 5v which is normal. Do I need to check something else on the power supply board, such as the regulator IC? I'm getting the same output regardlesss of if I have the lamp connected or not. Maybe I have a bad one.

    #14 4 years ago

    Nevermind, this is evidently a 2N6057 power transistor and not an LM323K regulator. My transistor got so hot the ink vaporized off and I couldn't tell what it was. That and some evidently incorrect advice I came across caused me to think it was a cross-compatible LM323K, lol. In this case I'll replace the 30 year old MC1723CP regulator IC as all the caps have been swapped.
    transistor (resized).PNGtransistor (resized).PNG

    #16 4 years ago

    Cool, thanks for the tip.

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