Commodore 64 restore

Discussion in 'Retro & Arcade' started by badmofo, Apr 6, 2019.

  1. money_killer

    money_killer Member

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    nice job!!
     
  2. OP
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    badmofo

    badmofo Member

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    Real life has been tearing me a new one lately so progress on this has slowed, but in the meantime I've taken delivery of some heatsinks, a capacitor replacement kit, and the recommended TS100 soldering iron. The iron is hilariously toy-like - I'm loving how small it is. I was convinced I had a suitable power pack for it in the shed but apparently not; I'll have a sneaky poke around in the cupboards at work tomorrow and hopefully track something down.

    [​IMG]

    Really looking forward to firing this thing up and replacing those 34 year old capacitors.
     
  3. flu!d

    flu!d KDE Neon 5.16

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    Those TS100's are actually pretty damn good bits of gear.

    [EDIT] It's interesting, I've got two C64 motherboards here, both are identical to yours but all the chips are socketed.
     
  4. OP
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    badmofo

    badmofo Member

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    Nice! I've only seen ~6 C64 motherboards in my life but none of them had all of the chips socketed - not even all of the major ones. That would save some time when troubleshooting.
     
  5. flu!d

    flu!d KDE Neon 5.16

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    It definitely does...Even if in my earlier days I removed the SID chip and touched one of the pins, killing the SID chip instantly... :(

    However, that's just my spare C64 motherboard from my original breadbin that I bought off a schoolmate in 1987 or something.
     
  6. Vanne

    Vanne Member

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    Really? Those SID's were that sensitive? Wow, no idea how mine survived. ;)
     
  7. OP
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    badmofo

    badmofo Member

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    Dunno if you can call changing an LED a mod but I'm deliriously tired so why the hell not - I've replaced the classic red power LED for a green one that I found in my stash of treasures. I'm surprised how much of a thrill it gave me to see it come to life - a subtle touch to differentiate this C64 from my other breadbin.

    [​IMG]

    And the ARMSID (http://dzi.n.cz/8bit/armsid/index_en.php) I ordered showed up - well packaged and with some nice instructions (in English which was thoughtful) (it hails from the Czech Republic). Installation couldn't be easier as long as your SID is socketed, which mine was thankfully. It was already sporting the latest firmware but I updated it just to see how it worked - super easy via a little BASIC program - and I was off and running. It's a bit "harsher" than the real thing, maybe harsh is a bit harsh, "brighter" might be more appropriate. Less organic? Whatever, it sounds a little different but not in a bad way, I think it sounds great. There's a good comparison b/w the real thing, the ARMSID, and some other clones here:

    http://kompjut0r.blogspot.com/2018/04/sid-8580-vs-armsid-vs-swinsid-ultimate_12.html

    Very cool:

    [​IMG]

    [​IMG]
     
    Last edited: Apr 18, 2019
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  8. OP
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    badmofo

    badmofo Member

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    Onward and upward - capacitor replacement completed. I'm lazy so just ordered a kit from this dude. I don't know if these are a great brand cap but I used the same kit for my other C64 and have no complaints after years of use.

    I was slightly put out to find that the specs for one of the caps in the kit (which differ by motherboard assembly) didn't match the original's 16v 100uf. The replacement was 25v 22uf, and the Googles were somewhat conflicted as to which was right. The cap in question sits on the reset line, so the thinking seems to be that a higher uf just means a longer pause on boot or reset. I decided to suck-it-and-see and indeed the machine boots noticeably faster now with no ill effects from what I've seen.

    The TS100 works well - I'm using a 19V PSU and the iron reported 300 degrees in about 20 seconds. That wasn't hot enough so a quick mash of the buttons later and up it went to 400 degrees.

    Next up is adding some heatsinks, and then I just need to sort out JiffyDOS and I'll be about done.

    EDIT: for prosperity, it was the cap at C24 that was a different spec to the original (16v 100uf)

    [​IMG]

    [​IMG]
     
    Last edited: Apr 26, 2019
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  9. OP
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    badmofo

    badmofo Member

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    This project has been waiting for the JiffyDOS ROM replacement I ordered to show up - it seems to be MIA ATM but while I wait for that to appear in my letterbox I decided to prepare by removing the existing Kernal ROM and dropping in a socket. That should have been a boring, easy task but I managed to cut 2 traces in the process, which resulted in dead C64. Patching them brought the machine back to life but it's still refusing to load a disk from my 1541UII+. I'm fortunate to have a working C64 here to experiment with and after much probing with my multimeter I'm confident that everything is electrically connected around the new socket, so I'm wondering now if I've killed something else during my f*@king around.

    Happily, detailed troubleshooting guides like this exist:

    https://ist.uwaterloo.ca/~schepers/MJK/dnp.html

    But I'm asking myself how far I want to go with this - I don't have a logic tester for example. I have another working C64 board in the shed, so I could just take the low road and go and hassle that one, but I know in my heart that what I should do is man up and fix what I broke. It would be a good learning experience and I'm in no rush to get this project finished.

    Can anyone suggest a good logic tester? :lol:
     
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  10. Vanne

    Vanne Member

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    sorry, I cant help you with a logic tester, but yeah, id probably wanna fix what I broke in the first place. cant wait to see how you get on. How are you finding that new soldering iron btw?
     
  11. Alby1976

    Alby1976 Member

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    Think I need one of these, just been using a generic 30w jaycar jobbie.
     
  12. OP
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    badmofo

    badmofo Member

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    Yes the new iron is very good, light and easy to work with on the small projects I do. I also bought some better, more tightly woven desoldering braid and that makes a difference too. I like that the iron seems to know when I've forgotten about it and first cools itself, and then turns off, and the tip seems to be decent quality.

    I was able to identify the disk loading issue with just my eyeballs in the end, no logic tester required. The legs of 2 resisters had come into contact somehow - I must have smooshed them together while I was desoldering the ROM. "It couldn't be that easy could it?" I asked myself as I bent them off each other and fired it up but yes it was - I pushed them back together to confirm.

    Still waiting for my switchable JiffyDOS to show up - the seller claimed to be out of stock when I inquired but magically got some back in stock the next day and sent shipping confirmation. In the mean time I've slapped heatsinks on the CPU and VIC-II.

    The last thing that's bothering me is that the serial number sticker is missing from the bottom of this case - I trashed it during the original cleaning / painting process. This dude sells replacements, and even lets you specify your serial no.:

    https://shop.pixelwizard.eu/en/commodore-c64/58/c64-serial-number-sticker

    But he didn't do the "Made in England" version we had in the AU. I asked him if he'd be interested in doing them, he asked for a pic and is in the process of adding them to his shop apparently - what a legend!

    Heatsinks: both the CPU and VIC-II get uncomfortably warm. There's some debate about whether heatsinks do anything much in the C64, there isn't much airflow after all. But there is a decent amount of ventilation once you remove that rubbish cardboard RF shield so I feel like the warm-air-rising effect will cause some flow. Also heatsinks look cool.

    [​IMG]

    [​IMG]
     
    Last edited: May 25, 2019
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  13. Vanne

    Vanne Member

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    mate, this is becoming a work of art! :D very very nice. Your inspiring me to start thinking about the restore on the C128D I've got.
    I love how your work is so neat, and i can't wait to see the Jiffy dos install. Are you going to use a switch? and if so, have you thought about where your going to mount it?

    I have a Jiffy dos wedge/rom setup in my c64c, but i wanna get Dolphin Dos. (no real reason, its just thats what my C64 had back in the day) The jiffy dos your getting, does it have the chip for the 1541?
     
  14. flu!d

    flu!d KDE Neon 5.16

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    I got the JiffyDOS EPROM for my 1541, along with JiffyDOS on my 1541 UII+ it works a treat. I really need to get some sexeh looking heatsinks for my C64.
     
  15. OP
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    badmofo

    badmofo Member

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    Thanks heaps and yes I will be getting a switchable chip like so:

    http://store.go4retro.com/jiffydos-kernal-rom-overlay-ic/

    I've used this product before and have been happy with it - in my other C64 I managed to sneak the switch into the RF modulator box in the place that the channel selector switch is on some units. Mine didn't have a switch so there was room and an existing hole in the case. I try not to drill holes in cases if I can help it. I'll probably look to to the same thing with this one.

    I use a 1541 UII+ like flu!d so that's super easy, I just bought a soft copy of the ROM and the UII+ is clever enough to be able to use it.

    Dolphin DOS sounds very interesting - faster again that JiffyDOS from what I understand but maybe less compatible? I accidentally turned JiffyDOS off the other day and thought my machine was dying - it's unbearably slow without it!
     
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  16. flu!d

    flu!d KDE Neon 5.16

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    JiffyDOS is already included with the 1541 UII+ and fully licensed, you don't need to buy the soft copy of the ROM. I made the exact same mistake before figuring this out myself!

    What you do need is the EPROM for any physical 1541 drives you may have connected to the unit to get the acceleration of JiffyDOS.
     
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  17. OP
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    badmofo

    badmofo Member

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    Dang it! Was that always the case? I bought the soft copy for my old, non "+" 1541 Ultimate II. I feel totally opulent owning 2 of those things - sometimes I wonder if I like them more than the C64 itself :weirdo:
     
  18. flu!d

    flu!d KDE Neon 5.16

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    If was always the case on the UII+, not too sure about the UII.

    Doesn't matter, JiffyDOS is pretty cheap until you have to buy the rare EPROM to fit a real 1541.
     
  19. Vanne

    Vanne Member

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    Should make some of those eproms.. but they are probably copyrighted?
     
  20. callan

    callan Member

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    How did I miss this thread???
    Great work Mofo. I have a few cases that are "beyond redemption" so I'm interested in that paint colour you tracked down.. I'm surprised your processor is pushing out heat: I never had that that on any I've worked with.
    I'm intrigued with the soldering iron. I recently got myself a decent base-station unit so I'm not in the market for a replacement - but it looks interesting.

    Callan

    edit: Oh a tip with Solder braid. It DOES go off after a while, and become less eager to sop up solder. I always go for the fine braided stuff, though..
    edit: edit.
    I always get my JiffyDOS from Jim Brain's shop. - He's always looked after me well and is well respected in the Commodore hacker community. Clever bugger, too: managed to work out how to hack past the the 6500 in the 1520 printer plotter to execute code in add-on RAM and, thus dump the ROM contained therein.
    I owned a Dolphin DOS contemporaneous since the mid 80's and it's an awesome piece of kit. Mine ended up being unstable: something I attributed at the time to a failure on the 1541 daughterboard but which I have RECENTLY discovered was a failing 1541 PSU. It is freaking awesomely fast and powerful, but it is a massive mod and, with it enabled you lose RS232 as well as tape: something JiffyDOS avoids.
    Callan
     
    Last edited: May 27, 2019
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