I’ve seen some 1200 Rev. 1D.1 boards missing the D215 (LM385), this will result in a higher voltage on the DAC VREF signal (U30) and noise will shown when you dragging workbench windows, accessing HD or floppy, etc.. When you place a LM385 then the picture will be much better. If the LM385 is broke, […]
Tag: amiga
Amiga CD32 Laser calibration & replace laser pickup procedure
WARNING! Before you start: I AM NOT RESPONSIBLE FOR ANY DAMAGE TO YOUR Amiga CD32 OR EYES! DON’T LOOK INTO THE LASER (BEAM)!! AVOID DIRECT EYE EXPOSURE!! ALWAYS COVER THE LASER WHEN TESTING/POWERING THE MACHINE!! USE PROTECTIVE GLASSES TO PROTECT YOUR EYES FOR BEING EXPOSED TO THE LASER BEAM!! Only continue with the procedures if […]
Working Amiga 4000 motherboard freeze then green screen after few minutes
@tbtorro Amiga 4000 motherboard works from cold boot, then freezes after few minutes and shows green screen after reset. Cold boot (after about 5 minutes) would restore the board, then symptoms repeat. No corrosion in the battery area. Solution: U212 controlling CAS/RAS is unusually hot, inputs are OK, but outputs show undefined “half” (pulling low […]
Amiga 1200 video DAC information
Some information about the video DACs If the Amiga rev 1 board uses ( or will be ): ADV101 D215, C215, R215 must be placed on the board. VP101 D215, C215, R215 must be removed from the board. On the lower pins of D233a a 1uF 0805 capacitor must be placed. If you […]
Amiga – What are those board jump wires ?
Amiga 1200 CCK clock signal – Alice to Budgie The technical reason is that the CCK clock signal coming out of Alice is not clean enough to drive the input on Budgie. It was cheaper for Commodore to clean the signal up using a buffer chip in stead of fixing the Alice chip itself. They […]