1/12 C64 repair: 'Out of memory' problem - the RAM chip conundrum

#c64 #commodore #repair

I've ended up with another 12 broken breadbin C64 machines! I figured I'll start making some videos repairing them and this is the first of those machines. I'll probably only briefly show the simple and boring fixes - but will make full videos on the interesting ones.

Episode 1: This episode!
Episode 4: Coming soon!

--- Video Links

Hakko Drill bit cleaner:
Part Number B1303 (sorry no link)

Adrian's Digital Basement Merch store:

Adrian's Digital Basement ][ (Second Channel)

Support the channel on Patreon:

-- Tools

Deoxit D5:

O-Ring Pick Set: (I use these to lift chips off boards)

Elenco Electronics LP-560 Logic Probe:

Hakko FR301 Desoldering Iron:

Rigol DS1054Z Four Channel Oscilloscope:

Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier:

TL866II Plus Chip Tester and EPROM programmer: (The MiniPro)

TS100 Soldering Iron:

EEVBlog 121GW Multimeter:

DSLogic Basic Logic Analyzer:

Magnetic Screw Holder:

Universal ZIP sockets: (clones, used on my ZIF-64 test machine)

RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI)

Plato (Clone) Side Cutters: (order five)

Heat Sinks:

Little squeezy bottles: (available elsewhere too)

--- Links

My GitHub repository:

Commodore Computer Club / Vancouver, WA – Portland, OR – PDX Commodore Users Group

--- Instructional videos

My video on damage-free chip removal:

--- Music

Intro music and other tracks by:
Nathan Divino
@itsnathandivino

[LeighKoven]

I don't know why, but I really like the repair videos. And I feel like the 64 is in that perfect space of being complicated enough that the machine can do interesting things (sound, graphics), but simple enough that you can actually diagnose it by hand.

[pb_magnet]

I'll always watch C64 repair videos. It's more about the troubleshooting process for me.

[Colaholiker]

I think it is incredible how you manage to pump out two videos (both channels combined) per week, despite working full time. And your videos are not some random garbage just to satisfy the Youtube algorithm but very well made and always worth watching, both for their content and also your very enjoyable style of persentation. (I think there isn't a single video listed on either of your channels that I haven't watched..😅) Big thanks from Haribo country!

[jeromethiel]

Not filler, it's why i watch your videos. Fixing things is it's own reward. Taking a broken thing and returning it to usable condition is just awesome.

[Sloxx]

Great video Adrian, love the split screen format. For those wondering, the part number for the Hakko drill cleaning tool is B1303. I've had it for a while, and it really has saved me from tossing out expensive tips that I thought were ruined. The spring tool that comes with the gun just wasn't working for them.

[projectartichoke]

You can never do too many C64 repair videos! Lots of people have them and they are prone to so many failure modes. And, you're also doing a very good job of imparting general troubleshooting knowledge every time.

[robcadwallader]

I am a simple man. If Adrian repairs a C64, I want to watch him do it.

[pmyhill]

The C64 repair videos are always fantastic to watch Adrian - please don't stop making them !

[viJ]

Adrian: When in doubt about making a C=64 repair video, make a C=64 repair video. :) We love seeing the particular symptoms of each machine and thinking along about the possible causes. It's like trying to solve a mystery before Holmes or Poirot.

[andrewadkins]

I enjoyed the video. You could look at it as not filler, but a training film. Trouble shooting, diagnosis, repair and testing the repair. It is a great educational video.

[madmanfrommars]

Even if I’m not understanding what you’re talking about because it’s far over my head, I love going through the troubleshooting process with you. Will not get sick of c64 repairs!

[frugalprepper]

12 in a row is fine! Bring them on! These repair videos are may favorite part of your channel.

[alnoorratansi]

c64 repair video's are never boring, keep them coming. don't skip anything

[d-rock]

Adrian, definitely appreciate these videos - no matter how many you make, I'll watch them. Your channel is one of the ones I've watched over the last couple of years that helped spark my interest in repairing retro electronics. Your various troubleshooting and repair videos have helped me immensely with the information and techniques (soldering, troubleshooting, etc...) that you demonstrate. With what I've learned, I've built a 'new' C64 using a Sixty-Clone board and was able to use an oscilloscope to diagnose an issue I had in the timing circuit for the VIC-II. I've also managed to assemble various project boards for the C64 such as a switch-less kernal switcher and a modern VIC-II timer circuit replacement board.

Thanks for sharing your knowledge and expertise so willingly.

[crowbarviking]

Thanks for fixing all those machines all the time. I love watching each single one of the repair videos. Even if it is the same error again or another retrobright.
Just as some people enjoy watching the same sport again and again, i love to see this again and again

[mogwaay]

I'm not really into the C64 HOWEVER I will happily watch you repair them till the cows come home! Just love hearing your thought process about how you go about fixing issues, it's just great communication and a total pleasure. I like to think your little tidbits it'll come in handy when I start fixing some of my broken machines that I have piling up (Electron, SMS2 and a 48k ZX), so keep me coming!

[Scubagon]

The C64 repair videos are always a pleasure to watch.

They're even better when the 8-bit dance parties are included!

[pipschannel]

Yep, that was definitely an (audible) issue with the low pass filter on that SID. But I would leave it in there. As long as the envelope & tone generators, amplitude & ring modulator and the bandpass filter work it should be ok to listen to.. Those pops give it some personality as you get with a vinyl record ;-) I wouldn't be surprised if that 'fault' has been in there from the factory as not all SID were created equal to begin with and the way the low pass filter behaves is the most variable component in my experience ;-)

[piconano]

Back in 1986, I designed an IC tester that would test all logic ICs of the time that was programmed into it. In circuit, while powered.
All the user had to do, was to remove the crystal of the CPU or any clocking source, and type in the part number after connecting the ribbon dip connector to the chip under test.
The tester would pulse the inputs and latch in the outputs and compare it with the truth table in memory. It was built around a Z80A.
While testing, I saw a new similar product in Popular electronics from B&K Precision. I became so upset, that I never worked on it again.
B&K pulled it off the market. It was like they came out with it, just to shit on my dreams and then left the room!!

[angrydove]

For people, like myself who loved them back when they were "the boss" and still do, we love to see C=64's get deserved TLC!