(Topic ID: 295518)

Sea Raider explosion question

By Jazorf

3 years ago

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  • 9 posts
  • 3 Pinsiders participating
  • Latest reply 3 years ago by OHEMIO
  • No one calls this topic a favorite


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    #1 3 years ago

    I recently picked up a midway Sea Raider and it’s complete and mostly functional. The main issue I’m having is with the explosion sound. My sound board is complete with reverb spring and all. The problem is one I’ve read about before. When a ship is struck the, the red lights flash and the explosion sounds but only briefly like a static crackle. If I manually hold the explosion relay in, it sounds like an explosion. I know the 500mf capacitor is supposed to hold that relay in for 2 seconds. I replaced that capacitor with a brand new one but it made no difference at all. Does anyone have any suggestion as to what to try next? The game is so close to fully functional. I already got the aiming and torpedo steering working so this is really the last function issue to solve. I’m good with EMs but when solid state components are involved, I’m a little lost.

    #2 3 years ago

    A 500mf cap should definitely hold that in for 2 seconds. Normally you can change the value of the capacitor up or down to change the duration of the hold time. I expect there to be a diode on there as well. Check the schematic if you have it or look at the coil tabs for evidence of missing diode legs. If the diode is present then check it to make sure it isn’t bad.

    #3 3 years ago

    If it adds any insight, it seems that the relay actually pulses twice when an explosion occurs rather than holding in. Like I said I replaced the capacitor and I check the 25ohm resistor that’s inline with it and that’s good.

    #4 3 years ago

    Would this be the diode you are referring to? If so, how do I test it? Solid state is not my forte.

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    #5 3 years ago

    I believe that is a diode. A very vintage diode. You need a volt meter to test the diode.
    If the relay seems like it’s pulling in twice very quickly then either it is being pulsed twice by the rotation of a cam switch that energizes. If the relay is pulsed by a cam then expect to see two lobes on the cam for each cycle of that cam. But it is likely that there is an issue with the diode / capacitor network that is causing the relay to drop out and reenergize. That diode is probably shorted causing the odd behavior.

    If you read a moderately low resistance with the leads on the diode one way and a high resistance with the leads the other, this is a sign that the diode is good. A diode should read relatively low resistance in the forward biased direction and very high resistance in the reverse biased direction.

    Open Diode

    If the diode reads high resistance in both directions, this is a sign that the diode is open. A diode should not measure very high resistance in the forward biased direction. The diode should be replaced in the circuit.

    Shorted Diode

    If the diode reads low resistances in both directions, this is a sign that the diode is shorted. A diode should not measure low resistance in the reverse biased direction. The diode should be replaced in the circuit.


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    #6 3 years ago

    Check these out: ebay.com link: JAN1N547 CG GE 1N547 RECTIFIER DIODE VINTAGE 1967 TIN LEADS NOS LAST ONES

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    #7 3 years ago

    There is a Sea Raider schematic on Ebay right now.

    ebay.com link: itm

    It’s too blurry to read but I can see a relay that looks like what you are working on. It has the following design. Make sure that your capacitor and diode are installed the correct way.

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    1 week later
    #8 3 years ago

    It was indeed the diode that was the problem. BTW, I’ve seen people looking for a replacement explosion spring. I think one of these could be cut and should work pretty well.

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    #9 3 years ago

    I have a few boards that I need to recap and investigate.

    My Sea Raider and for that matter SAMI sound cuts in and out intermittently or are weak.

    They are both up and running mechanically and I love everything about these games and the variety of game play they bring to my collection.

    Scheduling this in to get done is the question. Have 4 restorations pending and two in route from California on a carrier. One of them I picked up from Michigan.

    Good post and helpful to all whom are having this issue!



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