On 2012-09-22, at 18:11, Gerrit Heitsch wrote: > But while you're at it... if you feel like it, you could find out what's the minimal Vdd (usually +12V, pin 13) for VIC to give you a picture with colors. My last attempt was 3 diodes (1N4001) in series, lowering the voltage on pin 13 from 12V to about 10V and still everything worked. From my experience with a dead C90, I know that there is a voltage where everything still works but the picture loses color. For the 6569R3 involved that was about 8V. I checked with 6569R5. It seems to behave quite differently. The colour is practically all the time ther until sync is gone. I also use the Y/C amp proto in place of modulator so it might somewhat affect the results I guess (different amplification?) but also gives better picture of what's happening to the VIC's output as it affects it less. - 12V down to about 9.5V: almost no difference. Some banding artefacts below 11V but barely visible. - 9.5V down to 7.4V: everything works but picture deteriorates more and more in terms of banding, chroma bleeding, interference patterns/waves. While it may sound like really bad, it actually is not. It becomes clearly visible but - frankly - I saw people using those machines with similar or worse picture without complaining ;-) - 7.4V down to 6.3V: at 7.4 the charset becomes corrupted at edges. Getting more and more down makes the garbage eat more and more portions of the characters. At some point nothing is already readable and all charset is gone. Machine still works and colours remain in place. - 6.3V down ... : below 6.3V the colour goes off about the very same moment as sync, which may be the reason for monitor to drop the colour. Machine still works and can be brought back to normal by increasing the voltage. I didn't check the point where it would die completely. -- SD! Message was sent through the cbm-hackers mailing listReceived on 2012-10-07 15:00:44
Archive generated by hypermail 2.2.0.