Unstable 60hz output from my A1200(T)

[woody.cool]

Hi all,

Recently, I've started to notice that my Amiga 1200 (in tower) has started to develop a strange video output problem that only affects 60hz output (or output using the NTSC monitor driver)
This happens no matter whether it's from a game (WHDLoad or NDOS booted floppy) or from a Workbench friendly app.

My A1200 is of the following spec:

Hardware

• Commodore Amiga 1200 rev. 1D4 motherboard
• Kickstart 3.1 ROMs
• 68040 accellerator: Magnum MKII '040. Unsure of speed (can't remember withuot running SysInfo or similar) & FPU
• 10GB IDE Hard Drive
• 16x IDE DVD ROM drive
• IDEfix 4 way buffered IDE interface
• Internal High Density 3.5" floppy drive (1.44MB PC/1.76MB Amiga/insanely close to 2MB with DiskSpare)
• all in a nice EZ Z4 Tower (http://amigakit.leamancomputing.com/...roducts_id=700)

Software

• Workbench 3.1 (I changed hard drive recently and can't find my 3.9 CD or my 3.5 CD )
• WHDLoad 16.9
• MCP (can't remember version, but it's quite an old ish one)
• MUI 3.8
• MagicWorkbench 2.?
• NewIcons 4.6
• ClassAct 2.8 (iirc)
• all the usual unpackers (XPK, PowerPacker, LHA, LZX, DMS, ZIP/UNZIP, ARC, ZOO etc.)
• Deluxe Paint V
• PPaint 7.1 (for stuff that DPaint can't do)
• Transdisk in C: (you know, the pants command line one that's part of WinUAE)
• and that's about it

Like I say above, I've tried booting from floppy, booting with a minimal WB (so bypassing everything, doing a boot with no Startup-Sequence and typing LOADWB and ENDCLI at the prompt) and obviously a normal startup.

This is looking increasingly like a hardware problem tbh.
Any ideas?

All help/idea/whatever appreciated.

Thank you all in advance!

Cheers
woody.cool

[Harrison]

Could be a hardware issue. Only effecting one screen mode/resolution is a little odd, although grounding issues often effect things like this. What PSU are you using, and how old is it?

Might also be custom chipset issue.

[woody.cool]

Oh, the PSU is a 250W ATX PSU (can't remember the brand) which came with the EZ Z4 Tower case, so we're looking at approx 12 months old (if that) as I haven't had it all that long.
As for the Amiga 1200 .... well, it's the same A1200 motherboard (and 3.1 ROMs) that I've had for nearly 8 or 9 years, so that bit's getting old now!

[Phantom]

250W I think it's sufficient for what you have inside your tower.

[woody.cool]

250W I think it's sufficient for what you have inside your tower.

Same here!
I have ordered a 4GB CF card and a CF-IDE convertor, so will be 'loosing' the HDD when they arrive.