A few questions to ask, only because I perceive that you might be new to scopes. If I'm wrong, please don't take offense.
* Have you compensated the probes? * Have you checked your ground connection w/ a ommeter? * Have you compared these with what you get using 10x probes? That waveform is terrible! I don't even know what to say. :) -Josh On Wed, Dec 6, 2017 at 4:28 AM, Brian White <[email protected]> wrote: > Just playing with my scope. > All channels set to the same vertical scale and offset > M100 is turned on, powered by batteries, no power supply or any other cables > connected. > All probes set on 1X and all channels set on 1X to match. > > GND REF (probe alligator clips) = green wire by the battery & power jack > CH1 = X1 (8085 pin 1) > CH2 = X2 (8085 pin 2) > CH3 = RESET_IN (8085 pin 36) > CH4 = GND (8085 pin 20) (chip gnd relative to chassis gnd just out of > curiosity) > > Not pressing anything. > https://photos.app.goo.gl/q47eXNowgVMgVnRv2 > > Pressing reset. > https://photos.app.goo.gl/Nq5h0aFRXGii1CgS2 > > Consistent with the negative beep test, it also doesn't power itself off > after 10 minutes. > > No new info here, just exploring the scope and the m100. Grabbed the > screenshots with netcat! > > Most sources of 5v and gnd on various chips have that same .8v 10mhz noise. > > -- > bkw > > > On Tue, Dec 5, 2017 at 12:36 PM, Brian White <[email protected]> wrote: >> >> Good pointers to occupy myself with next at least. Thank you. >> -- >> bkw >> >> On Dec 5, 2017 7:04 AM, "Stephen Adolph" <[email protected]> wrote: >>> >>> did you swap the lcd to see if you get the same result? >>> >>> generally I end up resorting to probing each signal on each ram and rom >>> chip. Simplification would be to pull all ram modules but the first one. >>> >>> When using a scope to inspect the signals I toggle reset a lot and watch >>> the signals. when the M100 gets in a stuck state, many of the address lines >>> will be static. >>> >>> Start with D0-D7. make sure they all are toggling at the memory chips. >>> then go through the address lines. >>> >>> The main rom is accessed first. check that ALE and /RD are working as >>> well as the chip select. >>> >>> some ideas anyways >>> >>> On Tue, Dec 5, 2017 at 6:43 AM, Brian White <[email protected]> wrote: >>>> >>>> No beep. >>>> >>>> At power-on, RESET_IN on the 80C85 goes from 0 to +5v and stays there >>>> steady. >>>> There is a 5mhz sine wave on X1, and a slightly squared 5mhz on X2, and >>>> a 2.5 mhz square on CLK out. >>>> some of the other pins have square 5v pulses. >>>> >>>> All these chips have +5v on vcc (running on batteries) >>>> chip (pin#) >>>> 8085 (40) >>>> 8155 (40) >>>> 6402 (1) >>>> LH535618 (1) >>>> 6 x HM6117LFP (20) (the individual chips on the ram modules) >>>> >>>> One ram module socket empty >>>> Optrom socket empty >>>> >>>> Double checked I'm doing the blind beep motions exactly right by doing >>>> it on a good unit, then trying again on the bad unit. >>>> >>>> Thank you for giving me the excuse to finally pick up a scope. Got a >>>> rigol dso1054z and unlocked all the options except 500uv. I'm having fun >>>> playing with this thing. Guess I'll finally know how crap the sine wave is >>>> on my various UPS's. ;) >>>> >>>> -- >>>> bkw >>>> >>>> >>>> -- >>>> bkw >>>> >>>> >>>> On Mon, Nov 27, 2017 at 12:48 PM, Brian White <[email protected]> >>>> wrote: >>>>> >>>>> Can-do. Thank you. >>>>> >>>>> -- >>>>> bkw >>>>> >>>>> On Nov 27, 2017 7:14 AM, "Josh Malone" <[email protected]> wrote: >>>>>> >>>>>> I'd start with cold start, hit enter, type beep, enter, and see if the >>>>>> CPU and os is running. Assuming that they aren't, check the reset line >>>>>> with >>>>>> a scope to make sure the CPU is being reset properly on power up and that >>>>>> it's not held low (I think it's active low) since the nimh is in play on >>>>>> this one. >>>>>> >>>>>> Also check power supplies to the various chips. >>>>>> >>>>>> On Nov 27, 2017 12:34 AM, "Brian White" <[email protected]> wrote: >>>>>>> >>>>>>> Ok, what do I look at first? >>>>>>> I don't suppose there is a common/frequent/likely answer to that? >>>>>>> >>>>>>> https://photos.app.goo.gl/3MXUjFmttEETro7m1 >>>>>>> >>>>>>> I notice the pattern of bars repeats. >>>>>>> >>>>>>> I have 2 other working 100's and this is a 3rd I didn't really want. >>>>>>> I got it as part of an ebay item where I wanted something else. The >>>>>>> nicd was >>>>>>> just starting to corrode but hadn't yet leaked or anything. I've already >>>>>>> replaced it with a new nimh. >>>>>>> >>>>>>> I suppose it doesn't hurt to have a parts doner, but why not at least >>>>>>> take a shot at it eh? >>>>>>> >>>>>>> -- >>>>>>> bkw >>>>>>> >>>> >>> >
