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C64 repair videos [message #313646] Sun, 06 March 2016 05:20 Go to next message
frank is currently offline  frank
Messages: 48
Registered: May 2013
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Member
Hi all,
I've made a couple of videos while repairing some C64 for a friend.
You might find them useful for similar troubleshootings.
My english is not good, but I'm not a native english speaker anyway :-)

https://www.youtube.com/watch?v=4jndggJJ9QE
https://www.youtube.com/watch?v=GIrqtztvqYE

best regards

Frank IZ8DWF
Re: C64 repair videos [message #313800 is a reply to message #313646] Mon, 07 March 2016 18:44 Go to previous messageGo to next message
Clocky is currently offline  Clocky
Messages: 1212
Registered: December 2011
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Senior Member
On 6/03/2016 6:20 PM, frank wrote:
> Hi all,
> I've made a couple of videos while repairing some C64 for a friend.
> You might find them useful for similar troubleshootings.
> My english is not good, but I'm not a native english speaker anyway :-)
>
> https://www.youtube.com/watch?v=4jndggJJ9QE
> https://www.youtube.com/watch?v=GIrqtztvqYE
>
> best regards
>
> Frank IZ8DWF
>


Informative and interesting videos, thank you for posting :-)
Re: C64 repair videos [message #314218 is a reply to message #313646] Sun, 13 March 2016 23:45 Go to previous messageGo to next message
Anonymous
Karma:
Originally posted by: Thierry64

Thanks for this ! , looks very good


regards


Thierry


On Sun, 6 Mar 2016 10:20:49 +0000 (UTC), frank <frank@invalid.net>
wrote:

> Hi all,
> I've made a couple of videos while repairing some C64 for a friend.
> You might find them useful for similar troubleshootings.
> My english is not good, but I'm not a native english speaker anyway :-)
>
> https://www.youtube.com/watch?v=4jndggJJ9QE
> https://www.youtube.com/watch?v=GIrqtztvqYE
>
> best regards
>
> Frank IZ8DWF
Re: C64 repair videos [message #314224 is a reply to message #314218] Mon, 14 March 2016 06:36 Go to previous messageGo to next message
frank is currently offline  frank
Messages: 48
Registered: May 2013
Karma: 0
Member
Thanks guys!
I'm really glad they are usefull.
More will come I'm sure, I have some CBM equipment of my own that need
repairs.
CMB 4032, VIC-20CR and my first C=64 from 1984 for sure, probably a couple
of SX-64 too (one was working last time, the other not). I also have a
C=16 with black screen syndrome, but this will more likely require either
the TED or the CPU and I don't have any spare parts for it.
I'm starting soon to experiment my MOS8701 replacement project, this is
needed on the broken C=64, but that throws a black screen even with a working
8701, so it needs some more care after it gets it's clock back in good shape.

Regards
Frank IZ8DWF

Thierry64 <thierrykurt2000@hotmail.com> wrote:
> Thanks for this ! , looks very good
>
>
> regards
>
>
> Thierry
>
>
> On Sun, 6 Mar 2016 10:20:49 +0000 (UTC), frank <frank@invalid.net>
> wrote:
>
>> Hi all,
>> I've made a couple of videos while repairing some C64 for a friend.
>> You might find them useful for similar troubleshootings.
>> My english is not good, but I'm not a native english speaker anyway :-)
>>
>> https://www.youtube.com/watch?v=4jndggJJ9QE
>> https://www.youtube.com/watch?v=GIrqtztvqYE
>>
>> best regards
>>
>> Frank IZ8DWF
Re: C64 repair videos [message #314228 is a reply to message #314224] Mon, 14 March 2016 09:31 Go to previous messageGo to next message
Anssi Saari is currently offline  Anssi Saari
Messages: 327
Registered: January 2012
Karma: 0
Senior Member
frank <frank@invalid.net> writes:

I also enjoyed your videos, nice work.

> I'm starting soon to experiment my MOS8701 replacement project, this is
> needed on the broken C=64, but that throws a black screen even with a working
> 8701, so it needs some more care after it gets it's clock back in good shape.

Did you get volunteers to help with the 8701? From a quick look the 8701
just divides its input clock by 7 or 9 which is easy enough to implement
on any programmable device although I don't know if the quality is good
enough. OTOH, small FPGAs with a or two PLL included are cheaps these
days.
Re: C64 repair videos [message #314252 is a reply to message #314228] Mon, 14 March 2016 15:17 Go to previous messageGo to next message
frank is currently offline  frank
Messages: 48
Registered: May 2013
Karma: 0
Member
Anssi Saari <as@sci.fi> wrote:
> frank <frank@invalid.net> writes:
>
> I also enjoyed your videos, nice work.

thank you!
>
>
> Did you get volunteers to help with the 8701? From a quick look the 8701

nobody so far, but I am almost at the prototype level by now

>
> just divides its input clock by 7 or 9 which is easy enough to implement

not so... It has an internal xtal oscillator, probably just a NOT gate,
then probably first multiply the xtal frequency by two, then it divides by 9
or 7. The net result is that it produces two outputs:
1) the xtal frequency (which is 4 x color carrier of PAL or NTSC video)
2) xtal * 4/9 for PAL or xtal * 4/7 for NTSC
3) the two outputs must be "phase locked" and they have 50% duty cycle
(I'm not sure the 50% duty cycle is needed, but I'm quite sure the phase
lock is needed).

As far as I know, it obtains the phase lock by means of digital delays, it
doesn't actually implement a true PLL internally.
On the other hand, older revisions of the C=64 boards (up until 251138 afair)
use a true PLL composed by 4 chips + the VIC-II internal divide by 8.

> on any programmable device although I don't know if the quality is good
> enough. OTOH, small FPGAs with a or two PLL included are cheaps these
> days.

well, currently I ruled out the FPGA solution since 5V parts are almost
extinct and since many of them can't be soldered with my equipment and skills.
I do SMD works (for example a small RAM module expansion for Tandy TRS-80 M100
and clones), but I won't bother with bga and similar packages :-)

I changed my mind again, implementing a fixed delays solution like MOS
engineers did, would be too tedious (imho) and anyway, the smallest CPLD
that doesn't require a custom programmer is probably the ATF1502 now, and
that's a 44 pin chip, a bit overkill maybe. I'll try to implement a 6522 or
6526 with it instead :-)

I'm breadboarding a PLL currently composed by 4 HC logic chips and passives.
If it works, the SMD version won't be too large, considering that one
of the HC chips will be substituted by 2 x sot-23 single gates and
the other 3 will be soic-16.
It can live on a small daughterboard that plugs into the original 8701
socket. The C=64 board has no space problems for one of them, I need
to check the space on the C=64C board anyway.
I'm not an expert on designing PLL loop filters and VCOs, but probably
a bit of component tuning will get me on track (I hope) :-)
I can't blindly copy the original PLL design since it uses the divide-by-8
inside the VIC-II and that signal isn't present on the 8701 socket as
far as I know, so I had to re-design a PLL with a separate divide-by-8
solution and if I would use the original design, that would make the chip
count go at least to 5, not counting that the MC4044 isn't easily found
nowadays.
So, new PLL with different chips (available at mouser, digikey, anywhere).
Any PLL guru here? :-)

Regards
Frank IZ8DW
Re: C64 repair videos [message #314253 is a reply to message #314228] Mon, 14 March 2016 15:20 Go to previous messageGo to next message
frank is currently offline  frank
Messages: 48
Registered: May 2013
Karma: 0
Member
Anssi Saari <as@sci.fi> wrote:
> frank <frank@invalid.net> writes:
>
> I also enjoyed your videos, nice work.

thank you!
>
>
> Did you get volunteers to help with the 8701? From a quick look the 8701

nobody so far, but I am almost at the prototype level by now

>
> just divides its input clock by 7 or 9 which is easy enough to implement

not so... It has an internal xtal oscillator, probably just a NOT gate,
then probably first multiply the xtal frequency by two, then it divides by 9
or 7. The net result is that it produces two outputs:
1) the xtal frequency (which is 4 x color carrier of PAL or NTSC video)
2) xtal * 4/9 for PAL or xtal * 4/7 for NTSC
3) the two outputs must be "phase locked" and they have 50% duty cycle
(I'm not sure the 50% duty cycle is needed, but I'm quite sure the phase
lock is needed).

As far as I know, it obtains the phase lock by means of digital delays, it
doesn't actually implement a true PLL internally.
On the other hand, older revisions of the C=64 boards (up until 251138 afair)
use a true PLL composed by 4 chips + the VIC-II internal divide by 8.

> on any programmable device although I don't know if the quality is good
> enough. OTOH, small FPGAs with a or two PLL included are cheaps these
> days.

well, currently I ruled out the FPGA solution since 5V parts are almost
extinct and since many of them can't be soldered with my equipment and skills.
I do SMD works (for example a small RAM module expansion for Tandy TRS-80 M100
and clones), but I won't bother with bga and similar packages :-)

I changed my mind again, implementing a fixed delays solution like MOS
engineers did, would be too tedious (imho) and anyway, the smallest CPLD
that doesn't require a custom programmer is probably the ATF1502 now, and
that's a 44 pin chip, a bit overkill maybe. I'll try to implement a 6522 or
6526 with it instead :-)

I'm breadboarding a PLL currently composed by 4 HC logic chips and passives.
If it works, the SMD version won't be too large, considering that one
of the HC chips will be substituted by 2 x sot-23 single gates and
the other 3 will be soic-16.
It can live on a small daughterboard that plugs into the original 8701
socket. The C=64 board has no space problems for one of them, I need
to check the space on the C=64C board anyway.
I'm not an expert on designing PLL loop filters and VCOs, but probably
a bit of component tuning will get me on track (I hope) :-)
I can't blindly copy the original PLL design since it uses the divide-by-8
inside the VIC-II and that signal isn't present on the 8701 socket as
far as I know, so I had to re-design a PLL with a separate divide-by-8
solution and if I would use the original design, that would make the chip
count go at least to 5, not counting that the MC4044 isn't easily found
nowadays.
So, new PLL with different chips (available at mouser, digikey, anywhere).
Any PLL guru here? :-)

Regards
Frank IZ8DWF
Re: C64 repair videos [message #314329 is a reply to message #314253] Tue, 15 March 2016 16:31 Go to previous messageGo to next message
Ingo Korb is currently offline  Ingo Korb
Messages: 54
Registered: August 2012
Karma: 0
Member
frank <frank@invalid.net> writes:

> So, new PLL with different chips (available at mouser, digikey, anywhere).
> Any PLL guru here? :-)

Not a guru, but if you don't mind the slightly pricy chips and their
need for lower voltages, the CDCE chips from TI may be worth a
look. Programmable fractional PLL(s), multiple outputs with individual
dividers, configured via I2C and an internal EEPROM to select a default
configuration.

-ik
Re: C64 repair videos [message #314375 is a reply to message #314329] Wed, 16 March 2016 04:54 Go to previous messageGo to next message
frank is currently offline  frank
Messages: 48
Registered: May 2013
Karma: 0
Member
Ingo Korb <usenet@mail.snowcat.de> wrote:
> frank <frank@invalid.net> writes:
>
>> So, new PLL with different chips (available at mouser, digikey, anywhere).
>> Any PLL guru here? :-)
>
> Not a guru, but if you don't mind the slightly pricy chips and their
> need for lower voltages, the CDCE chips from TI may be worth a
> look. Programmable fractional PLL(s), multiple outputs with individual
> dividers, configured via I2C and an internal EEPROM to select a default
> configuration.

I've spent days looking at selection pages from various manufacturers, I
ruled out pretty much everything for one reason or another (no way to solder
with my equipment for example or the need to program it every time or
what else).
Feel free to suggest a specific part if you believe it would be good for this
job.
Anyway, I'm designing the PLL around an 'HC4046A, prototype should be
working by the next week if I get the design correctly.

Frank IZ8DWF
Re: C64 repair videos [message #314383 is a reply to message #314375] Wed, 16 March 2016 05:37 Go to previous message
frank is currently offline  frank
Messages: 48
Registered: May 2013
Karma: 0
Member
frank <frank@invalid.net> wrote:
> Ingo Korb <usenet@mail.snowcat.de> wrote:
>>
>> Not a guru, but if you don't mind the slightly pricy chips and their
>> need for lower voltages, the CDCE chips from TI may be worth a
>> look. Programmable fractional PLL(s), multiple outputs with individual
>> dividers, configured via I2C and an internal EEPROM to select a default
>> configuration.

just had a look again at the parts that you suggested, and yes, they might
do the job just fine, I wonder why I missed them the first time :-)
It needs a 3V3 regulator, but the output might be ok for 5V TTL inputs.
I'll give it a try before going to the multi-chip solution, thanks!

Frank IZ8DWF
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