I replaced my 40H decoder with a 7x part and have had no issues. The address decoder circuit failed in my 102 and it turned out to be the demultiplexer / decoder.
On Tue, May 1, 2018, 4:57 PM Jeffrey Birt <[email protected]> wrote: > Possible silly question…I have been able to find no data on the 40H244, > 40H245, 40H373 part numbers. Given their function and pinout I’m guessing > that a 74HC part would be an acceptable substitute? > > > > Thanks again, > > Jeff > > > > *From:* M100 <[email protected]> *On Behalf Of *Fugu ME100 > *Sent:* Tuesday, May 1, 2018 9:26 AM > *To:* [email protected] > *Subject:* Re: [M100] SPAM-LOW: Re: New member - question on 'half' alive > Model 100 > > > > If checking the buffers etc you should see the I0/M line toggle quite > quickly after power on and of course the ALE line. If it does not then it > is not even starting a proper boot, I feel your processor is OK they are > quite robust and well protected by all the buffers. > > > > I think you mentioned a click on power-on this could be the remote relay > clicking on, it is controlled by M14, this too is a symptom of an improper > boot sequence. This part also controls access to the ROM, if it does not > initialize correctly the ROM might never be accessed properly. > > > > The chip ids look good to start. You may also want to check continuity > to the ROM and RAM chips just to make sure there are no cracks in the > Address and Data PCB tracks. The quality of the M100 boards is quite low. >
