Unfortunately the NiCd battery was dead and already replaced twice. The unit was without power (no cable or battery) for several days since I struggled to find the NiCd battery.
Considering the age of the unit I think most of the electrolytic capacitors are dead. No one suggested to replace any specific capacitor... Do I have to consider the mass replacement or it is not a common issue on this computer? Mauro Sent from my iPad On 15/dic/2017, at 01:14, John Gardner <[email protected]> wrote: > If you're convinced it's stuck in a loop, removing all power (including > > the NiCd) for a time should fix that.... > > > > On 12/14/17, Mauro Pintus <[email protected]> wrote: >> Thank you Fugu and Brian for the feedback. >> >> Yes I tried the beep BASIC test with no luck and also the cold start (the >> M10 and the M100 are almost identical...). >> >> I made few other measurements trying to replicate what Brian is doing and >> for sure the unit is in a loop... >> >> In the linked google photo album I added another picture (the first one) >> showing the ROM CS (Pin 20 yellow trace) and the IO/M of the main processor >> (Pin 34 blue trace) >> https://photos.app.goo.gl/8YSbaAxZBuXu5rjC2 >> >> As you can see at the beginning of the repeted sequence, I get only 5 pulses >> on the IO/M >> >> The strange thing is that there is so little activity on the RAM CEx (chip >> enable), like nothing is loaded. >> >> Finally I measured also the CSx (chip select) on the LCD connector and none >> are moving, confirming that on the LCD nothing can be displayed. >> >> Mauro >> >> >> >> >> On Dec 13, 2017, at 7:01 AM, Fugu ME100 wrote: >> >>> Vee at –4.9V is good. >>> >>> You may have already looked at these options, so apologies if you have… >>> >>> The repetitive nature of the ROM CS cycling could be the CPU in a software >>> loop waiting for keyboard input. Have you tried the BEEP test from BASIC >>> to see if the motherboard is actually running? >>> >>> Have you tried a cold start? On the M100 press ctrl+pause while powering >>> on, not sure about the M10. It could be the memory is corrupted with the >>> loss of backup power. Always a good idea when first powering after >>> switching off/on the backup power.. >>> >>> >>> From: M100 <[email protected]> on behalf of Mauro Pintus >>> <[email protected]> >>> Reply-To: <[email protected]> >>> Date: Tuesday, December 12, 2017 at 5:24 PM >>> To: <[email protected]> >>> Subject: Re: [M100] diagnose >>> >>> Hi, >>> I have a not working Olivetti M10 and a Rigol DS1104Z oscilloscope, so I >>> made few measurement to try to help Brian and in the mean time try to >>> troubleshoot my unit. >>> >>> My unit was working properly and stopped as soon as I flipped the NiCd >>> battery switch off while the unit was ON (done by mistake with the cover >>> open). >>> Now the screen turn on but I can regulate just the contrast and no text >>> appear on the screen. >>> I also made a small arduino circuit to test the LCD alone, and I'm able to >>> write text on it, so the LCD should be fine. >>> >>> BTW I think Brian is using way too long ground leads on the oscilloscope >>> probe. >>> I made my measurement clipping the alligator clip to the metal case of the >>> main crystal that in the M10 is grounded with a pice of bare wire. >>> Is your scope grounded? I can see in one of your pictures the usual US >>> plug with only 2 terminals... >>> >>> Here are some screenshots of my measurements. >>> >>> https://photos.app.goo.gl/8YSbaAxZBuXu5rjC2 >>> >>> Pictures: >>> 1) CLK pin 37 of the 8085 >>> 2) Pin 7 of the 8085 >>> 3-4) CS Pin 20 of the ROM it seems to cycle over and over >>> 5) Reset * at power on >>> >>> VEE is 4.9V >>> V across the battery is 4.02 when the unit is on and 3.9 when off >>> >>> Tomorrow I'll continue hoping Brian or some of you can confirm/compare >>> some of my measurements. >>> Have a nice day >>> Ciao >>> Mauro >>> >>> NOTE: I think I will measure all the pins on the system bus so anyone with >>> an oscilloscope can do the same without opening the unit case... >>> >>> >>> >>> >>> >>> On Dec 11, 2017, at 9:28 AM, Fugu ME100 wrote: >>> >>>> Ah the “special tool” requirement always hated to see that in any >>>> step….. >>>> >>>> What did the –5V measure on the meter? If it is not within spec neither >>>> the LCD or buzzer will work. >>>> >>>> From: M100 <[email protected]> on behalf of Brian White >>>> <[email protected]> >>>> Reply-To: <[email protected]> >>>> Date: Sunday, December 10, 2017 at 11:30 PM >>>> To: <[email protected]> >>>> Subject: Re: [M100] Fwd: Re: diagnose >>>> >>>> Thanks for that tip. >>>> >>>> And oh like some GM repair manuals where replacing an entire transmission >>>> might be 11 steps, but one of them is to use the $12,000 machine no one >>>> outside of the factory has ever even seen. >>>> >>>> >>>> On Dec 8, 2017 1:38 PM, "Fugu ME100" <[email protected]> wrote: >>>> It might be better to use the CLK (37) output as a reference if it is >>>> needed. The CLK is derived from the X1,X2 XTAL inputs and should not be >>>> impacted by the loading of the scope probes. >>>> >>>> The M100 reference manual is quite good for troubleshooting some parts, >>>> although it does have a few broad instructions like “Check All IC’s”. >>>> :-) >>>> >>>> From: M100 <[email protected]> on behalf of Brian White >>>> <[email protected]> >>>> Reply-To: <[email protected]> >>>> Date: Friday, December 8, 2017 at 9:55 AM >>>> To: <[email protected]> >>>> Subject: Re: [M100] Fwd: Re: diagnose >>>> >>>> I noticed something a couple days ago. Those noisy gnd and 5v lines were >>>> only like that because I happened to have probes on both X1 and X2 at the >>>> same time. >>>> >>>> Later I was looking at a good M100, and happened to only be watching X1 >>>> and others but not X2, and everything was much better. But just by >>>> touching a probe to X2 while another was on X1, both gnd and 5v went >>>> exactly like those pics I posted from the bad M100. I can probe either X1 >>>> or X2 and it's fine, but not bith at the same time. >>>> >>>> I don't actually see any special reason to monitor either of those >>>> signals except briefly to verify they exist, or to provide something >>>> steady to trigger on while probing others. Just pointing out something I >>>> saw that explains those ugly traces. >>>> >>>> On Dec 7, 2017 11:45 AM, "Josh Malone" <[email protected]> wrote: >>>> Yeah - there is something very weird with the ground on that Tandy. >>>> Maybe some problematic traces? Or a bad IC leaking current to ground? >>>> >>>> Can you measure the DC power consumption? It should be ~60-70mA IIRC. >>>> >>>> On Wed, Dec 6, 2017 at 10:14 PM, Brian White <[email protected]> wrote: >>>>> After watching a youtube video about how to use an oscilloscope by >>>>> sparkfun, >>>>> I switched all probes and channels to 10x and adjusted the trim caps in >>>>> the >>>>> probes against the built in test signal to make the square wave look >>>>> square. >>>>> >>>>> With gnd ref on the cpu gnd pin 20 instead of chassis gnd, and a >>>>> couple >>>>> probes on X1 and reset_in, and one probe on chassis ground, now the x1 >>>>> and >>>>> reset_in signals are steady, reset_in looks flatter, and only the trace >>>>> for >>>>> chassis ground floats and bobs up and down now. >>>>> >>>>> So chassis ground simply floats around in relation to the rest of the >>>>> board, >>>>> or at least in relation to the cpu. Not a bad afe in the scope. >>>>> *chagrin* >>>>> >>>>> >>>>> -- >>>>> bkw >>>>> >>>>> On Dec 6, 2017 7:38 PM, "Brian White" <[email protected]> wrote: >>>>>> >>>>>> This is the bobbing I was talking about. It's dumb for me to even be >>>>>> talking about it yet since I haven't even done a basic comparison >>>>>> check on >>>>>> some other reference yet. >>>>>> >>>>>> https://youtu.be/b9jAYsfTOzQ >>>>>> >>>>>> And here's another look at a different signal hooked up a different >>>>>> way. >>>>>> Here, I have the ground ref hooked to the gnd pin 20 on the 8085, NOT >>>>>> the >>>>>> chassis ground. And CH4 is on pin 18, AD6. The offsets, trigger, and >>>>>> vertical scales are all visible on-screen. >>>>>> >>>>>> https://photos.app.goo.gl/mel4CKym2EtcV1352 >>>>>> >>>>>> https://photos.app.goo.gl/K1AIj3Pmt15xXfR72 >>>>>> >>>>>> >>>>>> -- >>>>>> bkw >> >>
