Commodore 128 Part 3: Future Proofing (Fail)

[@jaycee1980]

Time to have some fun with your 'scope :) I'd start looking at clock signals, make sure theyre all being generated correctly. I quickly found out on my own C64 that the VICII was dead when it wasnt putting out any CPU clock or Y/C signal, even though the input clocks were present.

[@GadgetUK164]

Re-watching this, I noticed a couple of scratches on the underside of the board - around 26:52. Have you inspected all the traces to make sure its not just a damaged trace? C128s do suffer from the odd trace going bad - I've seen a few with no more than a broken trace. Could just be coincidence and not related to the reversed cap.

[@HeyBirt]

Putting a capacitor in backwards is a right of passage in electronics :) It is really fun when the cap blows up, you will never forget that smell (sort of like a bad fish odor).

[@SianaGearz]

You know who else puts capacitors in backwards? Commodore engineers. It's often still wrong in the final silkscreen after the factory has been instructed to reverse them, but sometimes the actual capacitors just stay wrong for months or years of production. Commodore machines always need to be triple checked, need to take into account the silkscreen, the original orientation of capacitor, and engineering common sense.

[@mark12358]

That error occurred in manufactoring the A4000 desktop, on the audio section. The smd capacitors had been mounted according to silkscreen (where the main error was made), on the long run they will leak for sure.

[@mdftrasher]

When i hear "Full bridge rectifier" it gives me the creeps thanks to ElectroBOOM ;-)

[@MariaEngstrom]

Hehe! I have that T-shirt. AvE call them Full Bridge Rectum Fryer by the way. :]

[@rdxdt]

Its is not a puny single diode rectification.

[@JanBeta]

Yay! Love watching his videos. :D

[@JanBeta]

Lol! Reminds me to get a dose of AvE again. I didn't watch any of his videos for a while.

[@bknesheim]

Ref: 5:45 That mode is not only done in the factory. Have done at least 50 of those modes after market because the first 6 months all the C128 delivered had only US char-ROM. The first few times I did the upgrader there was a lot of nevers, but at the end I could do the mode in about 5 minutes.

[@FernandoelChachi]

I don't learn as much as when somebody shows the mistakes/problems. We all make (me a lot) things wrong from time to time and we all learn from them, and this is the best way to learn something. Thanks a lot for the video. Two days ago I tried to change a small chip from a board and it was the same: I was a bit of impatient and then I screwed all of the board with my so hot soldering iron erasing the connections. Lucky that mine was a new 20€ board, but lesson learnt in my case. You know: Shit happens ;)

[@csabasanta5696]

So it seems like a good practice to solder axial caps in with their polarity indication up. Thanks Jan for the great video and appreciate you putting this up for all of us to learn from. Wish it did not fry anything too expensive! Have fun!

[@vladeb1104]

You have shown us your true human side as even Jan Beta can do some mistakes.

[@chunk1978]

Good luck, Jan! I'm sure you'll successfully troubleshoot the problem. We believe in you!

[@IanSlothieRolfe]

It's a shame, and I'm sure its frustrating, but if its any cosolation Great content Janyou're going to end up knowing more about the 128 than you would have done if it had worked first time :) Great content Jan, and well done on showing your fails as well as your successes. It encourages those who are learning to persevere when they run into problems too.

[@feieralarm]

Good guy Jan: Messes up his board, just to give us another video of him fixing it.

[@IDPhotoMan]

I love to watch things go slightly wrong (like i'd do) rather than always perfect. Makes ya think

[@RobUttley]

Love the vids, Jan. Looking forward to seeing you diagnose and repair this. Cheers!

[@SnerkleBurger]

We learn as much from failure as success, buddy. You'll have this working in no time!

[@TheDefpom]

I’m sure you will get it fixed in the end. We have all broken things whilst trying to fix minor issues.

[@DanSanderson]

This was fun to watch even if it didn't work out (yet). I'm envious of that desoldering station!

[@robbiew73]

lets not forget, that shield is actually acting as a big heatsink in itself, that's why it is cemented to a lot of the chips! Just like the 'Shield' around the VIC-II on the older C64s - it's actually an old fashioned heatsink to distribute heat away from the VIC-II.. people seem to forget this!

[@xnonsuchx]

It's also always a good idea to look at the polarity of the originally installed part before replacing because a number of products have been found to have incorrect markings on the circuit board and you wouldn't know w/o a service manual or addendum/update.

[@JanBeta]

Yup, you're perfectly right. There's a number of vintage computers that have some polarity markers wrong on the PCB silk screen. The ones on the C128 seem to be correct, though.

[@MrWaalkman]

@24:12 Yeah, been there, done that... And most of the time on Commodore boards. They simply aren't meant to last forever.

[@JanBeta]

Yeah, the quality of the boards varies a bit. I found that the newer C64C boards are a bit better in that respect.

[@JohnGotts]

You'll get it working. Remember to change one part at a time, and always test between changes.

[@sulrich70]

Great work, tks for sharing and teaching us all! Don’t give up!

[@bit-ishbulldog2089]

Jan I F-in love the 128, as this is the so called Commodore 64 I played my first C64 games on.. My older, slightly older Brother got for a lotta ££££ in the mid to late 80's from what I remember. We had the C16 before that. I think he paid about £400-500 brand new from a computer shop, I went to school with the son of the owner of the shop, the son years later sold me Mega Drive games cheap that were new out at the time, he played but the sold them on to me.

[@CarlAttrill]

We learn from our failures and celebrate the lessons learned in our successes. Can’t wait for part IV mate 👍

[@wikusvandemerwe2762]

No problem. You'll fix it soon, and it will be a fun troubleshoot, then the machine with have even more stories to tell.

[@esshahn]

Only Hollywood needs happy endings - still great video and fingers crossed you get this troubleshooted Jan

[@GadgetUK164]

Looking forward to the next part =D

[@orjanh]

Great upload none the less. Kudos for posting a "failure" video, still interesting stuff - maybe even more than the usual successful videos you see all over youtube :)

[@rkornilo]

I think you succeeded in future-proofing it: nobody will be using it again in the future. ;-) I recently replaced the capacitors on my C64 (250407 Rev B) and when I removed the RF box, I ripped one of the 8 pins out of the RF circuit board, taking a part of the trace with it. Fortunately I managed to get it to where it belonged, trace and all. Haven't been able to test it yet, though, as the new power supply arrived (Nu-brick) and I have since discovered I forgot to solder in one of the replacement capacitors. Maybe this weekend. :-)

[@OriginalLictre]

A mistake in repair is an opportunity to engage in further research, and a reminder to keep details and proper technique in mind for the future.

[@asgerms]

The intro tune epitomizes the spirit of 8-bit computing. Where is it from?

[@ColdRFusion]

Polarity catches us all eventually Jan! Hope it is fixable, but it’ll be fun to watch. Good luck!

[@gregdunlap7538]

You could try booting it in 80-column mode and see if you get video out from the VDC; it does provide B/W composite video on one of the pins of the digital video out if you don't have a digital RGB monitor. If you do get a picture from the VDC then the problem is most likely with the RF modulator.

[@RetroRecipes]

Congratulat-- oh wait. Darn it! Have you tried 80 column mode if it's possible to boot to that? Or percussive maintenance? 😉🔨

[@peterbrandt7911]

My condolences, but it's a sign of character to release this video nonetheless. Good luck!

[@SianaGearz]

Condolences? It's possibly not quite dead yet, too early to call.

[@tails64dsntchannel8]

oh noo.. well, at least we will have a c128 troubleshooting video..

[@SkuldChan42]

My dad had one of these when I was a kid - one thing about them is you won't get a composite signal if the 40/80 column key isn't set right - not sure what happens if you try to boot one without the keyboard. The other thing - you can boot straight into C64 mode by switching it on while holding down the Commodore key.

[@MultiArrie]

my nephew had a c128 and i remember the command go64 or am i wrong

[@SkuldChan42]

MultiArrie both work but I was thinking he could test it quickly that way as well.

[@discoHR]

Happens. No worries, you'll fix it. If you get stuck and/or want to compare measurements to a working C128, let me know, I can check it on my C128.

[@orinokonx01]

I once heard that the silkscreen for the caps was wrong - the polarity was reversed accidentally. Good luck man!

[@Neffers_UK]

If it isn't broke, fix it until it is :D GL with the repair Jan.

[@FireballXL55]

Hi Jan, it happens to us all, I do it quite often when I check the polarity then the phone rings and I put the bugger in reverse. The bridge rectifier I would not use the desolder tool I would add fresh solder and heat all 4 legs rotating between them and pull the bridge out at the same time. Did you check the +12V although I think it only goes to the sid chip.

[@alexcochrane1966]

you'll get it sorted.

[@doktor6495]

Hi Jan! I also know that things can go wrong ... as you know (retro brighting my 1541 Floppy). But hey, don't worry, you can do it! Greetings from the Doktor! :-)

[@danielmantione]

If you ask me this is an excellent example why recapping Commodores is a bad idea. Measure those capacitors you removed, I'm confident they are in perfectly good condition. Soldering on complex electronic devices is never risk free. Voltage regulators are a completely different topic, but there is no need to "future proof" regarding capacitors: Should they break you can still replace them, but at least I never encountered a Commodore with bad capacitors.

[@danielmantione]

For repairs, and I think there is a good hope for repair, I'd start checking if there is a signal at all. If not check the capacitors in the modulator. Then check the clock frequency on the respective pins: If there is no clock, or a deviation of the clock frequency, the cause is a capacitor in the clock generator circuit. The remaining capacitors are mostly smoothing and decoupling and less likely to cause black screens.

[@redherring3110]

These things happen Jan. It could be good idea to check the RF modulator for possible mishap with capacitor change or maybe there is a short. If all seem fine I would suggest checking if modulator gets signal from Vic (pin 16-17) hopefully you don't need go too deep in the repair rabbit hole

[@mikewolf78]

Hi. Does your video scaler output 50hz modes on hdmi? I recently bought a scaler that supports only 60hz modes and it isn’t very good for watching 50hz sources.

[@JanBeta]

I think mine supports both 50 and 60Hz. It still has some ghosting when stuff is moving quickly on screen. Still looking for a better solution.

[@drkamilz]

Ok, Waiting for Part 4!

[@Mr_Meowingtons]

if the bridge rectifier is not a common failure then it is pointless to replace it.. IMO i would give it a good cleaning and replace all the caps and heat sinks to parts that get hot..;

[@SianaGearz]

I never replace all capacitors unless troubleshooting failure, just the ones that run warmer or are near to sources of noise or are known to commonly fail. If you take out a cap put it into your LCR and it reads as good as new after 20 years, then chances are it's a lucky one and will last longer than a new one you might put in, so right back in it goes. After all density is a common engineering goal today so the capacitors are not necessarily superior.

[@Mr_Meowingtons]

thats fine for you but i do a lot of amateur radio Radio and CB radio repair the caps all need to be changed out 80% of the time due to age all it takes is a electrolytic cap shorting out to make your day go bad and mess up a 1,000 Radio. Even on computer Power supply on vintage PC's that i work on all get replaced..

[@sheep1ewe]

On some wery old equipment there are actually some types that usually won't go bad ower time.

[@vittekantilles4178]

Schade Jan! Aber gutes Video und ich bin sicher du kriegst das Board wieder hin!

[@JanBeta]

Danke. Ich hoffe es!

[@lokz9632]

Great videos, keep up going. Anyone who works makes mistakes. I am sure you will fix it.

[@thetaleteller4692]

Thats why i remove all precious chips prior modding a board and checking voltages before putting them back.

[@144megabytes]

I have a 128 that has no keyboard but otherwise seems to work if you need parts.

[@terroshak]

FULL BRIDGE RECTIFIER !

[@MariaEngstrom]

Bad luck about the ripped trace for the bridge rectifier. :( I have 5 of these machines in various state, most of them work, some don't. It's kinda my favorite Commodore machine. :) I wonder, is the circuitry inside RF-modulator used also by the Composite or Luma+Chroma signals? If not I honestly don't see the point in replacing those caps. Because it's highly unlikely that computer will ever be connected to a TV via RF cable anyway? I would have even left the RF modulator out after de-soldering it and used that space for future upgrades instead. I would also never put the big RF shielding back, because it's just a pointless shield that Commodore made to please the FCC. Hope this does not come forward as criticism, because it's just questions and thoughts. Thanks for awesome content as always! :)

[@LeftoverBeefcake]

IIRC you can't remove the RF box on a 64/128 because it's still tied into the chroma and luma signals going to the monitor output. I know I've definitely skipped replacing the capacitors that are in the box after struggling mightily to get the box off the mainboard on one of my C64s. I didn't really notice any difference in the video quality between a machine with new caps and one with the old caps. Sure, the old caps will fail eventually, but I'll cross that bridge when I come to it. :P BTW glad to see another C128 user, they really are great machines.

[@MariaEngstrom]

Ah! Thanks for the update. :)

[@MultiArrie]

i use my c64c on a vga monitor via a svideo convertorbox. I replaced all the caps it improved the picture alot even in the 2in rf box made diffrence.

[@MariaEngstrom]

Is good to know, thank you very much. :)

[@azariayehezkel9064]

Im crying too :-( Good luck in next video We cross our fingers

[@EduArana]

Dont worry jan, to everyone who change radial caps happend that, because as everyone, we don't see the arrows indicators, only the black frame :p

[@PureAudioTones]

Hi Jan, sorry for that but sometimes it just happens, hope you can figure it out and fixed it with a nice informative video. (for forgetting to plug the power supply, a led on the supply might be useful in these kind of situations)

[@RETROCENGO]

Don’t worry Jan, im sure you will fix this lovly board up in the next video. You are great with this stuff😄👌🏻 Retrocengo

[@kluzz]

May I ask how you're connecting the C128 to your "LIPS" monitor?

[@stefanmarinescu5086]

Very nice video. You know the sure recepy for not making mistakes? Do nothing :) inspirational video. Like very much your Chanel.

[@rasz]

yay more content, best kind of "repair" :)

[@Maudio303]

shhh happens! Hopefully you can get this to work again. This week i desoldered the caps from my c64. The last cap won't get smooth out, so i pull a little to hard and yeah... some trace is broken :(

[@stephenbruce8320]

So sorry to see you ran into difficulties with you C128. If you have trouble getting schematics and documentation let me know. I will gladly share the documentation I have here.

[@josephnealescratchcards]

Awesome video as always

[@dennisp.2147]

Don't think of it as breaking an irreplaceable machine. Think of it as creating additional KZbin content! Everyone who has replaced capacitors has at one point f'ed up and put one in backwards. Cheer Up! You'll figure it out and then you'll be a C128 guru.

[@MindFlareRetro]

Oh no. Ouch. My heart sank when it didn't turn on. But I have to say, I've been there, too. I'm sure you might already have this fixed, however, did you replace the cap that was backward with a new one or just reinstall the same one? Might that cap be faulty now? Also, is the Z80 at U10 working ok (5V at pin 11, clock signal at pin 6, etc.)? -- 'The Z80 controls the bus on initial boot-up'. Anyway, my 2 cents. Looking forward to seeing you resolve this. Oh, and if I may, please don't call yourself an idiot. First of all, you are not that, at all. Second, and I've learned the hard way, self-denigrating one's self over and over will ultimately have a negative effect on your self-worth. Ok... another 2 cents. :)

[@groepi1972]

Hi Jan, es könnte an der Brücke zum Gleichrichter liegen. Du gehst unisoliert über Masse.

[@JanBeta]

Du hast recht. Das werde ich auf jeden Fall ändern. Danke!

[@Dkentflyer]

Hi Jan, I share your dissapointment that the C128 didn't work when you recapped it. I really hope you can figure out the reason why and then share with us.

[@tarstarkusz]

If it ain't broke... None of the caps showed any signs of aging/wear/heat damage, no leaking etc. Obviously you know what you're doing, but I NEVER replace more than 1 component at a time. None of them are known good and it only takes a second to make sure it powers up.

[@wimwiddershins]

Bugger! We've all done it. You double checked that gfx mod board? Good luck Jan. :)

[@EdwinNoorlander]

Hi Jan, just take your time. I now you can fix it. I think it’s the tv modulator.

[@JanBeta]

Thanks Edwin. I hope it at least makes for an interesting repair video. Might very well be the modulator. :)

[@Elrinth]

Ordered cap kit from retroleum.co.uk now. Thank you for this link

[@zzmaj]

In your case i voul replace rf modulator ;) I am not professional serviceman, but a huge lot of non working c64 and c128 I've fixed. I've found bad caps only near VICII only on oldest boards and only one capacitor brand. I have never seen FBR to fail. In C128 90% had dead ram, the rest was MOS ttl, CIA, ttl,power supply. I do have one misterious C128 that was fixed(bad ram) , but was on bad power supply and keeps going to monitor. Even all signals are ok, all chips are replaced, ram,ttl.I did not had spare Z80, so this is next thing on my list. At the end I will have fully socketed and recaped C128. On C64 side PLA, MOS ttl,ram is major fails, then 7701/8701 and CIA.

[@refractionpcsx2]

RIP Commodore 128 :( I hope you can work our what you fried :P

[@danielson9579]

I thought putting caps in the wrong way was just the done thing on commodores ;-)

[@Ramdileo_sys]

29:32 .... "It was at this moment .... he knew... he fuc%^&ked up" .. :-\

[@JanBeta]

Yeah, not the best feeling in the world. But the story ended well. (spoiler!)

[@svenpetersen1965]

Trotzdem, deine Mühe ist sehr wacker. Darf ich dir einen kleinen Labortipp geben: Deine Unterlage ist nicht wirklich antistatisch. Ich habe meinem kompletten Arbeitstisch für vielleicht 40 Euro mit einer ESD-Matte abgedeckt. Die kannst du über 1MOhm an PE anschließen. Und beim Arbeiten mit Lotsauglitze und eigentlich immer ist SMD Flux (Flussmittel) recht hilfreich. Gibt‘s auch bei ebay.

[@gyulaszabo6750]

Hu: billentyűzet nélkül a 80 oszlopos módban futhat a gép... RGBi kimenete él ilyenkor

[@MakarovFox]

FULL BRIDGE RECTIFIER!!!

[@JanBeta]

;)

[@insanedruid3143]

Just sacrifice some ZXs to the Commodore Gods and everything will work out fine, I guess ;)

[@tibfulv]

I usually would test between each component change to see if I still had a functioning machine. Sure, it adds to work time, but you're sure that whatever is the fault is your latest change; no need for troubleshooting. And the old woodworker's adage comes to mind: measure twice, cut once. Which really means check as much as possible, then do the work.

[@officermeowmeowfuzzyface4408]

Replacing diodes/rectifiers with "1000V" version is a VERY BAD IDEA. Reverse bias current increases with the forward bias voltage rating. If you understand what that means, you know how bad that is. And If you don't understand, you shouldn't be dabbling in electronics, let alone giving advice.

[@Archimedes75009]

Shocking ! German designs can be flawed ? One of my last hopes in mankind has just collapsed ;-(

[@LeftoverBeefcake]

Hey, even the best fail at one time or another... no big deal, I'm sure you'll have it up and running again in no time! ;) GadgetUK164 had a neat trick by using a Datasette (or a disk drive) to help troubleshoot a black screen C64 here: kzbin.info/www/bejne/kJ_LZ6evi7F6Y6c --- it's about 2 minutes in. Hopefully it can help you narrow down the fault. Oh and btw if you need a new VIC-II chip I have a spare I can send you.

[@Zhixalom]

I have also broken stuff on my C128's and felt like an impatient idiot afterwards. You will get running again, I'm sure. By the way, do you know this site? commodore128.mirkosoft.sk/

[@kentb3175]

The UK plug is probably the best designed plug of them all.

[@HuntersMoon78]

It has to be the most safe plug ever designed

[@thomassmith4999]

The Australian plug seems to work quite well

[@michaelhall6178]

A nice, secure contact between plug and socket; safety shutters built in to the socket - what's not to like about the British plug? Apart from when you step on one in bare feet, that is!

[@michaelhall6178]

And its size is a problem why, exactly?

[@lauriebot3941]

Michael Hall yeah, stepping on it is exactly what I was thinking too, that and lego must be the worst household things in the world to step on.

[@SeltsamerAttraktor]

Schick ihn mir, ich nehm ihn gerne =)

[@Groove1024]

your German! you should buy Würth Elektronik capacitors!

[@Groove1024]

and they look nice because they are red!!!! :) well they make really nice quality capacitors and it's a German brand and......... they are made in Germany!

[@Groove1024]

you can get them at Conrad of course

[@Groove1024]

i'm french and i usually buy this brand

[@Groove1024]

a reversed polarity capacitor is the must common error

[@JanBeta]

Yes, I love the look of the Würth ones. I have quite some Panasonic in stock right now but I might get some Würths, too, if I run out. Love the red. :)

[@JaySmith-cd1ln]

:)