Is it a MOS 8701 based clock circuit or a discrete PLL version? Probably the latter if it's an early C64 board. That's quite a complex circuit with lots to go wrong. You should be looking for a 14.31818MHz crystal and a working circuit for that for the colour clock, a divide by 14 circuit producing a 1.02MHz clock and an 8MHz voltage controlled oscillator producing the dot clock, which gets divided down by 8 by the VIC-II chip to produce another 1.02MHz clock. These two 1.02MHz clocks should be kept phase locked by the circuit controlling the 8MHz VCO. Have you also tried the standard C64 chips trick of finding another C64 board of the same era that's known to work, and swapping out all the socketed chips in the Pet 64 board for the ones in the other board? Richard On Dec 10 2010, Philip Lord wrote: >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 list > Message was sent through the cbm-hackers mailing listReceived on 2010-12-10 05:00:14
Archive generated by hypermail 2.2.0.