Sega NVS-4000-01 – 7.5A circuit protector trips, cracked LM1876TF

[bubbly]

Hello

I recently got a NVS-4000-01 PSU for my Astro City, but I’m having an issue with it.

As soon as I turn on the PSU, the 7.5A circuit protector (C.P.) trips.

I’ve tested it with only the AC connections attached, leaving all DC OUT connectors disconnected, so there is no game board or other DC load.

For reference, the cabinet works fine with its original 400-5198 PSU. I also have another NVS-4000 that powers up correctly in this cabinet, although it has a separate interference issue (light crest a different post for it later).

After opening the NVS-4000-01, I noticed that the LM1876TF (IC on the Sega Model 3 amplifier board is visibly cracked, near the mounting screw.


I’m wondering whether a shorted LM1876TF could draw enough current to trip the main 7.5A circuit protector, or whether I should be looking elsewhere in the PSU.

I’ve already found a replacement LM1876TF, but I’d like to check for other possible faults before installing it.

Has anyone experienced something similar with an NVS-4000 or Sega Model 3 amplifier?

Thanks!

 

[nipple]

is there an internal power cable to the amp you could unplug to see if that stops it blowing?

 

[bubbly]

Internally I think only the jamma audio input goes to the amp. AC go first to the amp and then goes though the outer AC OUT to the PSU

 

[bubbly]

Some updates
I’ve connected just the PSU board to a working NVS-4000 and it works. That was really great news.

So the fault must be only on the model 3 amp only.

I checked continuity on the fuses and fuse F2 was dead.
Then I checked the resistors and got OL on R21 and R26.
Tomorrow I’ll get the parts and replace the three of them. I hope that’s all.

LM1876TF it’s already seated.