Hi Mauro, On Wed, Dec 5, 2018 at 10:52 AM <[email protected]> wrote: > > 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'm glad you solved the problem, I don't think the original modules can be easily repaired they are made on a kind of ceramic subtrate, but I might give them a try if you want. I'm also making replacement modules for the M10 and compatibles since some years. You can contact me privately of course. > > 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 [email protected] 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 <[email protected]> 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 > <[email protected]> wrote: Mauro, What do you need to repair your M-10? > Greetings from the TyRannoSaurus Jan-80 ________________________________ > From: Mauro Pintus <[email protected]> To: [email protected] 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 <[email protected]> On Behalf Of Mauro > Pintus Sent: Saturday, December 1, 2018 7:50 AM To: [email protected] > 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 4,99€ 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 > > > > > 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 >
