Commodore Amiga A3640 Repair / Recap - 68040 

The other thing I obviously did here - at the point it wasn't working at all, or giving display problems - feel the temperature of each of the chips on the A3640. That could help you work out if one has died! Something strange - did anyone notice the walls in Doom seemed sloped lol? NOTE: The other difference between 040 and 060, the 060 needs an extra 74F257 and resistors and caps I think! Those probably come fitted on an 040 to 060 adapter, and they are on the A3660 from Chucky. In order to use the MAPROM feature you need to load the Kickstart via command line (as I tried in the next A3640 video!) NOTE: When I cleaned up around C105 you can see the wire is loose! I spotted that later, removed the cap again, soldered it back down, and refitted the cap again! That was done just before it went back - after the video was complete!

The old saying still holds true "THOU SHALL TEST VOLTAGES". As for recapping sometimes people do more damage than good these old boards are fragile so they require a very delicate touch.

As always excellent work and an excellent video - FWIW: I particularly like you include your thought processes in your videos, and even your errors when they crop up along with why they were errors. Very helpful for learning, thanks. On the subject of learning I guess the primary issue with this board is the person who previously recapped it could have done with a bit more practice?

Great video, I find it so awesome that people are making new replacement boards for things like this. Thanks for posting!

Hollow soldertips can be quite handy and used to remove excess solder.

I used to love magic menu 😊

That frontier elite intro is classic! just heariing brings back memories..... It was a long time ago but... if memory serves some of the missing FPU instructions were emulated in an 040 version of the MATHIEEEdoubtrans.library located on one of the workbench 3.0 install disks which I had to copy over and if I remember right had to rename, please forgive my old mind if am wrong... I ran an /x BBS on an A4000 for a few years - good times...

Saving rare treasure... good job.

Recently fixed a A3640, had one broken trace due to corrosion.

This just makes me want a video game in which you fly your spaceship over a huge Amiga motherboard, dodging power connectors and CF cards, while bad electrolytic caps shoot globs of electrolyte at your ship, and they’ll weaken the shields and slow down the ship until you get back to base to clean it off with vinegar and IPA. 😀 Crazy, huh? 🙂 Oh, and those LEDs on the accelerator card turn into powerful turbo lasers that’ll blast your ship to bits!

I've told you before - MuMapROM util to put boot roms into fast RAM. If you are using MMULib, you have to install it (choose simple option, Expert install has 100s of options). Original 68040.library had huge bugs, which is why Thomas Richter wrote a replacement. He maintains MMULib to enable a user to implement a custom version of 680X0,.library to do that and more to this day, 25 years plus of commitment. Most modern Workbench (3.1.4) will actually complain if you don't have a 680X0.library on the system (but will still boot).

Coldspray and a hairdryer can be used to pinpoint intermittent problems caused by soldercracks.

Great work gadget. I can recommend Pattex Repair Extreme or UHU Repair Extreme for fixing capacitors and other stuff on boards. I don't like hot glue.

Wow, that was a tricky one to pin down.

28:31 Depends on the type of flux. Amtech NC-559-V2-TF (my favourite) doesn't burn up, it's consistently in liquid state regardless of the temperature used. It's very sticky and hard to clean though. Ultrasonic with distilled water and Flux-Off Aqueous is recommended. That's what I use.

The beachball test on the 040 is normally lightning fast with FPU enabled in AIBB. It should not go to black screen. Maybe faulty FPU?

I assume someone's already mentioned this but anyway always check for dry solder joints especially cracked ones that can always be an issue if you've done just ignore this

You can use my Sprintfiles and sprint layout to check where pins goes on the 3640 :)

If you want a challenge, I have a rev 2.1 (not a typo) a3640 that needs some help. I wish there was more information on a3640 repair but it seems to be mainly around re-cap and damaged traces in those areas. This board had no such issues from what I could see under the microscope, but does have some older GALs. I know the GALs had to be upgraded for use in the a3000 due to timing issues. I would even include a 040 to 060 upgrade board for the a3640 for you to show and keep for your channel.

Nice man

I remember on irc a person called zorak wrote a small program for me to put in devs that sped up my hd speed on my 040

I had a 040 at 40mhz with 128mb ram on my A1200 with a power computing idie power flyer the system ran pretty damn quick for what it was 🙂

Yes, the “real” 68040 has the FPU instructions, but the 68LC040 does not. I don’t know about any MMU, though, or if the ‘LC040 had the 6-stage instruction pipeline or not.

Thou shalt check voltages

Is that a XC68040RC25M? The text is in a weird place and in a strange font. Has someone added that after it left the factory?

Nice, good job. Is there a petition anywhere for AmigaKit to use more amps capable connectors? I'd sign it, my A4000 also has significant voltage drop on their connector.

should there be a lead running from the chip resistor beside R401

Now days a $5 ESP32 can run Doom at 20fps.

24:44 it looks like you soldered your tinned via to the pad of capacitor C105.

Can you please contact me with regards to some faulty boards, A2000, Blizzard boards, and a splash of disk drives and A1200 boards with issues.

01:02:10 Did you just skip over the slow part (the planet surface, most demanding)? :)

Chris can i give you a link a non working taito type X2 on ebay

Why didn't you put new pads on i would never do this hack job