Thanks Richard, Maybe I should have checked there first... The reset pin 40 on the 6510 seems to get the correct reset signal, It starts low then goes high. Can I assume that the reset is working? Maybe next I should look at the clock circuit as it doesn't look like I'm getting any pulsing. Does anyone know what I should check next? Cheers..again Phil On Dec 10, 2010, at 11:42 AM, Richard Atkinson wrote: > Start from the 6510 RESET# line and work backwards. What is that > connected to? > > > On Dec 10 2010, Philip Lord wrote: > >> Ok this morning I printed out the schematic and theory of >> operation for the C64. >> >> The theory of operation states that the reset signal is originally >> produced at pin 9 of the 556 time (MC3456p in my case). The output >> is active high. I have tested this pin with my probe, and it does >> indeed switch from low to high on power-up. The theory of >> operation then says that this signal is sent to pin 13 of a 7406 >> hex inverter (U8) and the output from the 7406 is active low from >> pin 12...this is the reset signal. >> >> However, on my machine pin 9 of the 556 is tied to pin 13 (on the >> same 556) with some wire, and I have tested the continuity from >> pin 9 of the 556 to pin 13 of the 7604, and I can't see any >> physical connection between these pins which in contrary to the >> schematic and the theory manual. Maybe I'll pull the board out and >> have a look at the bottom side for any damage or cut traces. >> >> I probed pins 12 and 13 of the 7406 and pin 12 is always low and >> pin 13 is always high. >> >> So I'm a little confused...this doesn't seem right. Maybe I can I >> briefly apply 5v to pin 12 of the 7604 to see what happens? >> >> Maybe I have the wrong schematic, but I don't think so. I'll look >> for others anyway. >> >> >> >> >> On Dec 10, 2010, at 12:43 AM, MikeS wrote: >> >>> The supply voltages to the ICs are all correct? >>> >>> Reset line is being released? >>> >>> >>> ----- Original Message ----- From: "Philip Lord" >>> <random6000@mac.com> >>> To: <cbm-hackers@musoftware.de> >>> Sent: Thursday, December 09, 2010 3:23 AM >>> Subject: Re: Pet64 DOA >>> >>> >>>> Well, it seems like the power might be ok after all, so I broke >>>> out my logic probe...it's a cheap one but has helped me fix >>>> many simple issues over the years. >>>> The first think I noticed after probing around is that I'm not >>>> getting any pulsing (or at least that what the probe >>>> indicates), lines are either high, or low, or nothing, but >>>> there doesn't seem to be any pulsing at all! >>>> So I guess I should look at the timing circuit or Xtal? Anywhere >>>> else? Not sure how to test is a Xtal is working as I don't >>>> think my probe can do that. >>>> Cheers >>>> Phil >>>> On Dec 9, 2010, at 2:10 PM, Philip Lord wrote: >>>>> Great...so then maybe my power voltages are all good? Should I >>>>> find some test point on the C64 motherboard and get some >>>>> voltages there? Any idea what I should check next? >>>>> >>>>> Re-PET board. Ethan has been working very hard, and he believes >>>>> he has fixed both boards now (but can not test loading as his >>>>> C2N data cassette deck is in need of a new drive belt). Last I >>>>> heard everything is almost packed up and ready to ship. It >>>>> would be great to get the boards back before years end, as I >>>>> have been building a number of add-ons in anticipation for >>>>> their arrival and I'm excited to try everything out. >>>>> I have built one of Nicolas Welte's Ram/Rom boards which will >>>>> hopefully take my ram to 32k and allow me to use various basics >>>>> (V1 through V4) and not have to worry about failing RAM in the >>>>> future. I have also built a number of adaptor boards to >>>>> replace the video ram and character ROM. Finally I got myself >>>>> a C2N232 as I don't know how reliable the original cassette >>>>> drive is. I'm hoping to 'fail proof' this machine for at least >>>>> another 30 years ;-) >>>>> >>>>> >>>>> >>>>> >>>>> On Dec 9, 2010, at 1:44 PM, MikeS wrote: >>>>> >>>>>> 5V DC and 9V AC - sounds OK. >>>>>> >>>>>> Did you finally get your PET boards back and working? >>>>>> >>>>>> m >>>>>> >>>>>> ----- Original Message ----- From: "Philip Lord" <random6000@mac.com >>>>>> > >>>>>> To: <cbm-hackers@musoftware.de> >>>>>> Sent: Wednesday, December 08, 2010 10:41 PM >>>>>> Subject: Re: Pet64 DOA >>>>>> >>>>>> >>>>>>> 8.91 vac >>>>>>> On Dec 9, 2010, at 12:31 PM, MikeS wrote: >>>>>>>> Hi Philip! >>>>>>>> >>>>>>>> What AC voltage do you get between the two white wires? >>>>>>>> >>>>>>>> mike >>>>>>>> >>>>>>>> ----- Original Message ----- From: "Philip Lord" <random6000@mac.com >>>>>>>> > >>>>>>>> To: <cbm-hackers@musoftware.de> >>>>>>>> Sent: Wednesday, December 08, 2010 10:07 PM >>>>>>>> Subject: Re: Pet64 DOA >>>>>>>> >>>>>>>> >>>>>>>>> Sorry maybe I should have tested the some lines using AC not >>>>>>>>> DC. >>>>>>>>> So here again is what I believe I have (suing the black >>>>>>>>> line as GND): >>>>>>>>> White: - 5.8 vac >>>>>>>>> (KEY) >>>>>>>>> White - 0.5 vac >>>>>>>>> Black (I'm guessing this is ground) >>>>>>>>> Red - 4.98 vdc >>>>>>>>> Of course I could just be confused as I've never owned a >>>>>>>>> C64 before. >>>>>>>>> Looking at schematics seems maybe the two white lines >>>>>>>>> could/ should be 9vac, and maybe the red line should be 5 >>>>>>>>> vdc??? >>>>>>>>> Phil >>>>>>>>> On Dec 9, 2010, at 11:16 AM, Philip Lord wrote: >>>>>>>>>> I just got myself a PET64 from Yahoo Auction Japan. Quite >>>>>>>>>> a rare machine I hear, so I'm not sure how one ended up >>>>>>>>>> in Japan. I got if for a decent price as I don't think >>>>>>>>>> the Japanese knew exactly what it was. >>>>>>>>>> >>>>>>>>>> Anyway, It arrived the other day, after a quick internal >>>>>>>>>> inspection, I powered it on. I can hear the transformer >>>>>>>>>> buzzing(!), but no action at all on the screen at all, >>>>>>>>>> and it doesn't seem like the chips are getting warm at >>>>>>>>>> all Maybe need to leave it on a little longer to make >>>>>>>>>> sure, but I didn't want to do that incase bad voltages >>>>>>>>>> kill anything more). >>>>>>>>>> >>>>>>>>>> There are 4 wires leading from the small PCB which is >>>>>>>>>> attached to the transformer to the C64 motherboard, and >>>>>>>>>> I have measured the voltage from the black wire (GND?) >>>>>>>>>> to the 3 others. Here are the reading i get: >>>>>>>>>> >>>>>>>>>> White: - 100mv >>>>>>>>>> (KEY) >>>>>>>>>> White - 100mv >>>>>>>>>> Black (I'm guessing this is ground) >>>>>>>>>> Red - 4.98v >>>>>>>>>> >>>>>>>>>> That's as far as I have gotten. Next I will remove the >>>>>>>>>> motherboard and see where exactly these 4 wires go. >>>>>>>>>> Anyway, I was just wondering if anyone had any insights >>>>>>>>>> or thoughts. >>>>>>>>>> >>>>>>>>>> Cheers >>>>>>>>>> Phil >>>>>>>>> Message was sent through the cbm-hackers mailing list >>>>>>>> >>>>>>>> Message was sent through the cbm-hackers mailing list >>>>>>> Message was sent through the cbm-hackers mailing list >>>>>> >>>>>> Message was sent through the cbm-hackers mailing list >>>>> >>>>> >>>>> Message was sent through the cbm-hackers mailing list >>>> Message was sent through the cbm-hackers mailing list >>> >>> Message was sent through the cbm-hackers mailing list >> >> >> Message was sent through the cbm-hackers mailing list >> > > Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing listReceived on 2010-12-10 04:00:10
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