Long story short: SUCCESS!!!!!! My M10 is working fine. Thank you everyone for the huge help and usefull advise provided in the past and recently. A BIG THANK YOU to Francesco Messineo I think you neiled the issue and the chain of event that caused the RAM to fail.
Litthe explanation of the repair process: Removed M3, M4 (decoders), M7, M8, M9 (all my RAM Modules). Tested M3 and M4 with a TL866 -> good Installed IC machined sockets. Installed M3 and M4 back in place Installed only one RAM module in M9 position PC tested -> FAIL Replaced RAM Module PC tested -> FAIL Replaced RAM Module with the last one available SUCCESS!!!!!! Out of 3, I have 2 broken RAM modules :) I think I don't need another M10 unless I don't want to restore/expand the RAM size. Do I have other options? Is REX available for the M10? Thank you everyone Mauro Il 04.12.2018 12:08 mau...@tiscali.it ha scritto: > Sounds possible, thank you!! > For the same reason and to get used to the new desoldering tool I'll first remove and test the 2 decoders M3 and M4 (40138). > > Mauro > > Il 04.12.2018 09:24 Francesco Messineo ha scritto: > >> On Mon, Dec 3, 2018 at 11:00 PM Mauro Pintus wrote: >> >>> Checking some signals with the oscilloscope it looks like it is looping after a fix time without completing the boot. Francesco Messineo (another user of this list) wrote me in this days to offer some help and he suspect I damaged the RAM. Thank you again Francesco. I bought a desoldering iron and I hope in the next few days I'll find the time to try removing all RAM modules and fit one at a time in the first socket (hoping one module is still alive). >> >> I actually suggested the RAM could be damaged when he opened SW3 (the >> RAM backup power) with SW5 (the main power switch) closed is that some >> logic and the RAM have Vb as Vdd rail and almost the rest of the >> system has Vdd derived from Vp (via the dual output inverter). Now, if >> you look at the schematic, SW3 removes both Vb and Vp, but, on Vb >> there's only a few bypass capacitors to ground plus 1 uF electrolytic, >> so it might discharge quickly, while on Vp there's at least one 470uF >> capacitor plus another 470uF on the output of the inverter on Vdd side >> (yes, also much more logic powering from it, but stil...). >> What might happen in this case is that the Vb got quickly to 0V with >> still some inputs of the chips powered from it have something like +5V >> applied; in this case, the protection diodes on the input start >> conducting and some of them might get shorted or degraded from this >> current. It happened a few times on logic that I designed that had a >> backup power for CMOS RAM, I had to make sure that all inputs to the >> RAM were either following Vbackup or already switched to logic 0 >> before removing the backup power. >> So in this situation I would examine all the logic powered directly >> from Vb and that includes the RAMs. Usually a quick test with a >> multimeter (with all circuits powered off) from each input pin to Vdd >> pin of the chips can show if there's some damaged input protection >> diode. >> >> HTH >> Frank IZ8DWF >> >>> Sent from my iPad On 03/dic/2018, at 19:06, Jan Vanden Bossche wrote: Mauro, What do you need to repair your M-10? Greetings from the TyRannoSaurus Jan-80 ________________________________ From: Mauro Pintus To: m...@bitchin100.com [3] Sent: Saturday, 1 December 2018, 16:12 Subject: Re: [M100] Olivetti M-10's for a new home Thank you Jeff, really appreciated. Now I keep my finger crossed :) Have a nice day Mauro On Dec 1, 2018, at 3:59 PM, Jeffrey Birt wrote: Mauro, You have a need for them, so you should have them if the original person does not speak up. Fixing your machine is a better use. I have no specific need, just thought it would be neat to have a machine with AZERTY keyboard. Jeff_Birt From: M100 On Behalf Of Mauro Pintus Sent: Saturday, December 1, 2018 7:50 AM To: m...@bitchin100.com [5] Subject: Re: [M100] Olivetti M-10's for a new home I was soo exited I didn't see the other answer from Jeffrey, I'm sorry... Hope we can find an agreement, I'm really interested but I don't want bother anyone. Mauro On > > Con OpenStar hai Giga, SMS e i minuti che vuoi da 4,99EUR al mese, per sempre. Cambi gratis quando e come vuoi e in più hai 10EUR di credito omaggio e 6 mesi di INFINTY! http://tisca.li/myopen [7] Con OpenStar hai Giga, SMS e i minuti che vuoi da 4,99€ al mese, per sempre. Cambi gratis quando e come vuoi e in più hai 10€ di credito omaggio e 6 mesi di INFINTY! http://tisca.li/myopen
