Need Help: Modded Amiga 1000 Mystery Connectors

[Guru_Meditation_Error]

Got a crusty 1000 the other day and noticed these extra connectors on the back. Popped the hood and ran into this mess. She came with an extra 1.5MB Ram via a Microbiotics Starboard sidecar.

Any ideas?





Thanks,

GME

[mechy]

the short brown loops are extra grounding for the pal chips. helps reliability.
someone had added what looks like 2 extra audio jacks, not sure what is going on there since i cant see where the cable goes to.

[bloodline]

Can you scope the outputs of those extra audio ports?

[Oldsmobile_Mike]

Would need a bigger picture, or some indication where those wires go, as Mechy said.  Could be anything from the original jacks failing and those were just tapped in, or the owner wanted to hook up two receivers (without using a standard splitter), to something a lot more exciting (what is going on there at the connectors?  Looks like a chip and some resistors?).  Looks like a fun project getting her restored!  

[Guru_Meditation_Error]

A few more detail shots:

[Guru_Meditation_Error]

And some wiring stuff. Wire A runs under the daughtercard and connects to a spot next to the power supply plug Wire B looks like a ground, yes?

[IanP]

Wire B is ground common to both outputs. Wire A looks like it's going to the Op-Amp on the audio output of Paula. So it probably by-passes the normal Amiga audio output filtering. Wire B is attached to a connector to allow the motherboard to be disconnected from the mods attached to the case, wire A will need to be unscrewed from the ground point to release the motherboard completely from the case mods.

[JimS]

Maybe that chip is a power amplifier chip, and the mod is to allow the Amiga to drive speakers directly.

[Framiga]

Maybe that chip is a power amplifier chip, and the mod is to allow the Amiga to drive speakers directly.

that's not a chip, is a connector.

A divider or impedance adaptor? who knows! :-)

[Ilwrath]

Wire B is ground common to both outputs. Wire A looks like it's going to the Op-Amp on the audio output of Paula. So it probably by-passes the normal Amiga audio output filtering. Wire B is attached to a connector to allow the motherboard to be disconnected from the mods attached to the case, wire A will need to be unscrewed from the ground point to release the motherboard completely from the case mods.

Oooh.  Great memory.  I bet you're right.  You can't bypass the audio filter in software on the A1000.  (All other Amigas can software bypass, this is indicated by a dimmed power light when bypassing.)  Those jacks are likely filter bypassed audio out.

[bloodline]

Oooh.  Great memory.  I bet you're right.  You can't bypass the audio filter in software on the A1000.  (All other Amigas can software bypass, this is indicated by a dimmed power light when bypassing.)  Those jacks are likely filter bypassed audio out.

I agree, this looks like a low pass filter bypass.

[Guru_Meditation_Error]

Awesome. Thanks guys, I owe you one.  I'm not familiar with audio, is there any advantage to this setup?