(Topic ID: 283680)

Bally bridge rectifiers (alt)

By hockeymutt

3 years ago



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    #1 3 years ago

    Hey everyone wanted to give everyone a heads up here, was rebuilding my rectifier board for an 8 ball and stumbled upon Vishay bridge rectifiers that didn’t require heat sinks was able to find the nte equivalent locally.

    PART NUMBER : NTE 5394
    Max at: 100c or 212f (boiling)
    Amps : 35
    Volts:1000
    They are in sip form but was able to get the 3 to fit nicely

    44791DF3-B453-4CBC-BEBE-EAE43A40A2B1 (resized).jpeg44791DF3-B453-4CBC-BEBE-EAE43A40A2B1 (resized).jpeg
    #2 3 years ago

    How hot do they get after a few hours of play?

    #3 3 years ago

    Yes, they still require heat sinks - especially BR1.
    This style has a lower thermal resistance from 'junction to case' than the GBPC style but still requires a 'case to ambient' heat sink.

    Common part number is GBJ3504
    https://www.greatplainselectronics.com/proddetail.asp?prod=GBJ3502

    I have recently been searching for a decent heat sink for use with this style for use in the upright position.

    #4 3 years ago
    Quoted from G-P-E:

    Yes, they still require heat sinks - especially BR1.
    This style has a lower thermal resistance from 'junction to case' than the GBPC style but still requires a 'case to ambient' heat sink.
    Common part number is GBJ3504
    https://www.greatplainselectronics.com/proddetail.asp?prod=GBJ3502
    I have recently been searching for a decent heat sink for use with this style for use in the upright position.

    Thanks gpe! Local electronics shop didn’t see an issue when I brought it up. I have to dig around to see what heat sinks I have to see what I can get to work.

    #5 3 years ago
    Quoted from vid1900:

    How hot do they get after a few hours of play?

    Not sure as of yet, trying to work out all the kinks currently. Game will never be on more than 6-8 hours. Will update once I get everything going

    #6 3 years ago
    Quoted from G-P-E:

    Yes, they still require heat sinks - especially BR1.

    Even if you use LEDs ?

    #7 3 years ago
    Quoted from GRUMPY:

    Even if you use LEDs ?

    LEDs will drop BR1 current by a bunch but do you really want to use the bridge rectifier as a fusible link?
    BR1 and his accompanying heat sink must be capable of handling whatever is installed at fuse F1 which is normally 10A.

    Even BR3 runs quite hot in many machines during games - BR3 should also have a heat sink (even though many people don't).
    When I get time to sell rectifier boards, I put bridges on all three.

    These GBJ bridges have a 'typical' junction to ambient thermal resistance of 22 C/W
    They don't list the maximum thermal resistance which is what you should always design to.

    Each diode has a forward voltage drop of 1.05 volts. Full wave operation so there are always two diodes operating at any one time.

    Using the typical thermal value and you operate at 10 amps (fuse rating):
    power dissipated = 2 diodes x 1.05 volts x 10 amps = 21 watts
    operating temperature = Ambient + (power x thermal resistance)
    Assuming ambient temperature = 35C
    Temp = 25 + (21 x 22) = 487C! That's 908F!

    For curiosity sake, if you run a GBJ35 at maximum current of 35/2 or 17.5 amps - these will theoretically get up to 833C. Liquidated.

    If you reduce current load down to 2 amps
    power dissipated = 2 x 1.05 x 2 = 4.2 watts
    temp = 25 + (4.2 x 22) = 117C or 242F

    Even with a 2 amp load - this bridge would burn up.

    With a real low LED current load -
    If 'somebody' in the future replaces just five LED lamps with #44 regular lamps, the bridge will burn up over a period of time.

    #8 3 years ago
    Quoted from G-P-E:

    If you reduce current load down to 2 amps
    power dissipated = 2 x 1.05 x 2 = 4.2 watts
    temp = 25 + (4.2 x 22) = 117C or 242F

    And this is why I asked. Thank you.

    3 weeks later
    #9 3 years ago

    Give an update, had this game on for 12 hours straight and rectifiers stayed between 90-100 no heatsink and ambient temp was around 65-68.

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