Is my A1200 broken or not?

[Firefly]

Ok, so I bought a used A1200 with GVP accelerator for $200 off eBay.  I plug it into a TV via RF, and I get nothing.  Black screen.  Composite on TV. Still nothing. I install the accelerator.  Still nothing.  I hook it up to a VGA monitor with an adapter.  I get a garbled screen (too high/low refresh rate?)  I unplug the harddisk, thinking it may be boot-related.  Still no dice.

The only thing that makes me think my Miggy isn't plain dead is that I get a somewhat distinguishable screen as I power off the VGA monitor.  I think the refresh rate is tooo low or something, but I have no way to tell.

Is my poor miggy dead?

Please help!

[Firefly]

Well, I tried Composite on a known good Composite hookup on my TV (normally has a Gamecube hooked up) and it's coming up with a black screen.

Also, this may help to give you guys a better understanding of what's going on with the RF; When I have the RF hooked up, it goes from static when the Amiga is off, to a black screen when the Amiga is on.

Is there some sort of A1200 hardware mod that requires disabling the Composite ports or something?

Also, as far as VGA goes, I thought you only needed a scandoubler for Amiga modes, and that the A1200 could do VGA resolutions as well?  Is there any way to force the A1200 into VGA mode?  Perhaps someone can provide me with a boot disk that will force the Amiga into this mode?  I believe there is a way to write Amiga disks on a PC (I remember doing this when I had my old A1200 to make a copy of Champions of Krynn)

Thanks again, Amigans, for helping a newbie out!

[Firefly]

Well, it looks like my only recourse at this point is to either buy a scandoubler/flickerfixer, or an A520.

Cana nyone point me in the direction of a service manual or somesuch that I could test this with?