jlavi@ujocs.joensuu.fi (Jarkko Lavinen) (02/17/91)
Answer: Smoke I have Lucas accelerator in my A1000 and guess what: It does not work! Led flashes, I can hear the boot song. With 7474 as U9 I can even load kickstart disk. After that power led really starts to flash and in sequence I can see different colors in screen (at least grey, yellow, green...). The interesting thing is that PALs U4 (Eclk, decade, CPCS) and U5 (VMA, HIGHZ) are running exceptionally hot. I don't dare to keep my machine on as smoke may not be far away. Within few days I hope I get logic probe at my hands so I will check few lines but until then digital multimeter is my only guide. At least I check better U4 and U5 outputs. With multimeter I have checked that the outputs are not shorted. What else can it be? What can load PAL's so much that they warm so exceptionally ? They receive clock, I think (at least the pin voltage is in forbidden area, so it's probably pulsing). Jarkko Lavinen
jlavi@ujocs.joensuu.fi (Jarkko Lavinen) (02/18/91)
Well, with the help of a friend I have been able to step over this fear of steaking eggs over PALs. Using proper U9 he was able to boot the machine up few times (18Mhz flakey, 14Mhz steady). However, the PALs were still unexceptionally hot and my friend agreed on this. I am not going to invest icecap for pals. Mine pals read TIBPAL16R4-12CN (top) and F6191053 (bottom). Could somebody tell me what these markings mean in fact? Jarkko Lavinen