Alpine MRX-V70 Fuse Configuration

[SN95GT50]

Picked up an Alpine MRX-V70 (5-Channel) amp second hand, get what you pay for. Anyway, running two cheap 10" subs bridged from the sub output, no problem there. Running my rear speakers bridged, fronts running off of a different amp. Running it with a pair of RCA cables running from the head unit, balance thrown to left side, both RCA cables detached at the amp, take the left RCA.

• Connect it to CH-1(L) got sound out of both speakers
• Connect it to CH-2(R) got sound out of both speakers
• Connect it to CH-3(L) no sound
• Connect it to CH-4(R) no sound

Pulled fuses to check them, top one is fine (used voltmeter), removed second one and the fuse is broken literally only one leg came out. Leads to my first question, how are these things fused? Are the fuses in parallel and they can run off one fuse as long as the load isn't too great? If that is the case why not just run 1 larger fuse?

Finally got the leg out of the fuse holder and put in a new 30 amp fuse, now I have sound no matter what port I plug the RCA into.

Figured I jacked up the speaker wiring, checked that about a million times, left speaker is connected to CH1(+) & CH2(-) Right speaker to CH3(+) & CH4(-)

I have the Channel 3/4 switch set to 1/2 - cut and paste from the manual: "This switch setting is for selecting either 2-channel for 4-channel input mode. When set to “1/2”, signal will be copied from CH-1/2 and sent to CH-3/4, eliminating the need for y-adapters."

The only thing left that I can think of is something internal to the amp. Any suggestions for searching? I am not intimidated and am willing to tear this thing apart.

Thanks,
John

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