Try removing the RAM, one at a time…
From: M100 [mailto:m100-boun...@lists.bitchin100.com] On Behalf Of Charles Hudson Sent: Saturday, October 17, 2020 2:14 PM To: m100@lists.bitchin100.com Subject: [M100] Model 100 Boot Issue? Delving deeper into the mystery: With no batteries in the tray and no adapter powering the unit I measured the voltage of the (nominally) 3.6V 80mah backup battery at 4.3 VDC. I had replaced the original with this battery a few years ago and it appears to be in good shape. (I bought mine on eBay). I also checked the power switch and the adapter socket for continuity; both passed. I unplugged the cable to the display and checked for corrosion; I can't see any evidence in the cable, the battery tray or the motherboard in that area. I looked up crystal X1, which seemed to have a foreign substance around its base: either glue / insulator or something has leaked. I don't know if there is anything in a crystal that could leak, but I couldn't test the crystal directly anyway. Instead I found the 80C85 and located pins 1, 20 and 37, and attached a frequency counter to 20 and 37. The counter was set to sweep from 1.5 MHz to 3 MHZ. With power applied to the motherboard the counter never "latched" on any frequency. It's too soon to blame the crystal, though: Referring to the troubleshooting matrix #1 in the Service Manual, I checked everything listed up until I got to the "converter transformer", which was not referenced by part number. I assume it is the one near the power switch, and I took a guess as to which was pin 1. If I guessed right, I did not find the expected voltage. I removed and replaced C82 and C83 as recommended but that did not solve the problem. I took some pictures for the benefit of any interested parties: https://drive.google.com/file/d/11gkvYUbYowW8TM8zglytiRFqBSvOLlmz/view?usp=sharing, https://drive.google.com/file/d/1BoU6FzNwI6ZIIugVMHL1gieF5Mjrueil/view?usp=sharing, https://drive.google.com/file/d/1M5wl4RLkGL4oSCo6qvCEW8CdmPPl_IVJ/view?usp=sharing, https://drive.google.com/file/d/1g5F2R15J0sJ3UBLnhmxMWurtETGTnaaF/view?usp=sharing. Thanks for your help so far: Any further suggestions welcome. -CH- <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> Image removed by sender. Virus-free. <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> www.avast.com
