I’ve finally taken the jump into retrocomputing with something I’ve always wanted to own, a proper Commodore PET, or CBM 3016 to be exact!
The seller said 5 years ago when it was last turned on, that it worked perfectly fine. However I do wanna take some precautions before reawakening it. Not that something blows after all this time.
I however am still pretty new to retrocomputing and wanted to ask the experts on here, If/what I should first inspect under or over the hood before turning it on? Thanks in advance!
Electrolytic capacitors loose some of their passivation layer. This needs to be present to make them DC insulators. Without it, they are a dead short. So while it reforms, they are resistors and heat up. This can be a problem. To allow the heat to dissipate and the passivation layer form properly perhaps try this: Plug it in for a moment only, repeat 3 times. Turn on and right off again and repeat 3 times.
If you see any damage capacitors replace them. Generally replacing all electrolytic capacitors is a good idea. Essentially those pesky tantalum ones.
Hm I see. So plug in for around 3 seconds and then unplug again 3x. Then turn it on and instantly off again, also 3x. How long should I run her for afterwards? Only like a Minute to ease her in or go all in?
And once she’s home work on replacing all electrolytic Capacitors, sounds good!
If you replace them anyway… just do only that. To test functionality it could indeed help avoid explosions.
Havent replaced parts like these or soldered things before, so it’ll definetly be interessting. Though out of curiousity, if the Capacitors do explode, would they damage other electronics in the system or would it only be limited to itself?
The explosion should not damage anything short term. Leaving the residue will cause a lot of corrosion long term. If you get into soldering, make sure to buy proper flux. It makes such a huge difference. Also not the cheapest iron. I would recommend a TS80P. For removing parts, if you do that more than a few times, get an automatic solder sucker, cheap ones should do. Otherwise use the iron with extra solder at high heat and perhaps 3 or 4 hands.
Ans dont forger that must be done under a hot shower.
Don’t know the chemistry behind that, but if it’s start to read/write info could that not cause corruption? It just seems like your bios and OS would be unimpressed
What do you mean? Electrolytic caps should only be used for power rails, them failing means the DC is either absent, at the wrong level and/or with excessive AC components.
Get a multimeter. Open the computer. Inspect any batteries for leakage.
Measure voltage of batteries make eure they are in spec.
Inspect every capacitor, look for bulges. Use your multimeter and check for shorts across caps.
Eyeball everything else. Look for discoloration or anything out of place.
No advice, sorry… but DAMN!!
That was my first, at school 7th grade learning BASIC.
god it was amazing. You are lucky
Why lucky?
I don’t know if five years is long enough for this to be a problem, or how long it would have needed to stay powered on five years ago in order to avoid the problem, but beware: Electrolytic capacitors that have been sitting for too long can behave badly when first powered up again.
I suggest you read up on the topic, and consider whether it makes sense to replace or reform the relevant capacitors, before you flip that switch.
A couple links that came up in a quick search, to get you started:
https://hackaday.com/2023/06/05/protect-vintage-gear-with-easy-capacitor-reforming/
Very nice! Sadly I have no idea what to look out for before turning it on. A searchydoo of the internet brings up some videos on restoration that may be useful but you’d have to watch them to really know.
Wow, I didn’t even know that that was something to be concerned about. I will be much more cautious when I finally dig my Atari on the storage. It’s been probably 20 years since it’s been turned on. I don’t even know if it would turn on at this point. Thank you for the heads up!
@Mr_Mofu Fire extinguisher?
Will definetly be there when I do
You should first make sure that it’s plugged in.
But before you buy it, probably ask the seller to actually try turning it on.
Won it in an auction. The way the rules around that work is that if it doesnt work or is broken, the deal is canceled. So on Tuesday I’ll come over for a personal visit to check it. If its all fine I’ll take it home If not then the deal is canceled. Though if I can avoid breaking it then and there by taking some precautions, then I’d wanna do that!
