Startup of my old AppleII computer ...

[MarcoPajotter]

Hi,

Since May of 2024, I'm fully retired.
And today, with some good intentions for 2025.
So, time to clean up, and repair some old stuff I found in my [mans cave].

I started to clean my old Apple II, and my old Diskdrives.
Will see if this old computer will start up, without any problems ...

I already found some old APPLE II books and manuals.

And I found my first software cassettes ... from 1978 (Yes, which proofs I'm older guy)

Question)
Before I start up my old AppleII, is it better to replace the old capacitors, or just start up and see (smell) ?


Greetings from pajottenland, belgium.
marco

[Yuri]

MarcoPajotter wrote:

Question)
Before I start up my old AppleII, is it better to replace the old capacitors, or just start up and see (smell) ?

It's probably not a bad idea to just pop the cover and have a look at the electrolytics and see if they've swollen/leaked/popped or whatever.

https://en.wikipedia.org/wiki/Capacitor_plague

[GARTHWILSON]

In 1982-1983 I worked as a repair technician at TEAC and fixed over a thousand tape recorders in that time, and the only failed electrolytic capacitors I ever saw were the larger power-supply ones where they did not do adequate derating, for example using a 25V or 35V capacitor in a 24V power supply, instead of going the next step up to 50V.  The smaller ones, like 1µF or 10µF seldom come below 50V anyway, and I never saw any of those fail.  From 1985 to last year, I was in audio communications for aircraft, and never saw an electrolytic capacitor fail in all those years of our products.  I did circuit design, and the occasional repair; but the repairs were always other things, like a relay that went south or a monolithic ceramic capacitor that died an infant death, or switch contacts that just needed spraying, or damage from abuse.  In your case, the capacitors are apparently older though, so it wouldn't be a bad idea to replace the electrolytic capacitors.  The .1µF ones across every IC should be totally fine.  Where I'm working now, the boss just got an ESR tester and wants me to check the ESR of all the electrolytic capacitors in old units when I do a repair, and replace them if they've gotten too high.

Regarding your signature line, your English is very good for someone whose first language is not English.

[greghol]

At minimum replace the RIFA cap in the power supply. It will blow and make alot of burnt butter smell as well as smoke. I pulled my dads AII plus from his garage rafters and used for a few days and then walk back out in the garage where I had it my house. Luckly it was in the garage and not in the house so the wife didn't get PO'd. It lingers for a few days.

The cap is on the power in mains across hot and neutral. I never replaced it but this reminds me to order one with the next Digikey order.
It is used to filter out PS switching noise from the AC connection going out. It is the long yellow device in attached pic.

https://www.reactivemicro.com/product/r ... er-supply/

Greg

[barnacle]

Capacitor Plague [tm] appears to be a specific issue which is related to products from around the turn of the century. That's probably not going to affect an Apple II which is twenty years older. That said, you are likely to find at least some capacitors which have failed over time: Adrian Black's youtube channel (Adrian's Digital Basement) shows many cases where this is the case.

I've always worked in an environment where components are conservatively rated and so capacitor failures are rare (though there was a famous example of a professional video mixer where the manufacturer put three hundred tantalums in backwards!) so I don't have a great deal of direct exposure to the issue.

If I were replacing electrolytics I would select Rubycon as one of the best options, and I would rate the replacement at least double the voltage of the rail it's sitting on, e.g. a sixteen volt part for a five volt rail (most TTL logic); a twenty-five volt part for a twelve volt rail (rs232).

Neil

[BigDumbDinosaur]

Greetings, Marco.

The aforementioned “capacitor plague” occurred well after Apple ceased building the II series, so that should not be a concern.  That said, you should carefully examine the top of each electrolytic under a magnifier for signs of bulging, cracking or other distress.  If you don’t see any such thing, it should be safe to power up the machine.  However, it is advisable to do so with the cover off so you can see if anything starts to act strangely.

As Garth notes, electrolytics from the time when your Apple II was manufactured tended to be good quality...at least the ones used by Apple.  Commodore was reputed to use cheap-quality caps as part of Jack Tramiel’s efforts to sell at a rock-bottom price.  Not surprisingly, age-related failures in Commodore machines occur now and then.

[BigDumbDinosaur]

Yuri wrote:

https://en.wikipedia.org/wiki/Capacitor_plague

In the early days of the AMD XP processors (c. 2002), we used quite a few ABIT KG7 motherboards in our workstation builds—these boards used an AMD 761 northbridge, which was the best-performing northbridge of the time available for use with AMD MPUs.  ABIT was probably the largest motherboard producer that got bitten by junk electrolytics and during the time, we built around 80 machines with KG7 boards, unaware of the electrolytic problem that was ensuing.

It wasn’t too long before we started getting calls on failed systems.  In less than two years, every machine we built with a KG7 board went belly-up, all of which had blown electrolytics.  In some cases, the failures ended up ruining MPUs, which caused me to put in a claim to ABIT for the losses incurred.  Much to their credit, they reimbursed us for the cost of, if I correctly recall, about 20 failed MPUs, as well as every board we had purchased.  When I found out about the bogus caps, I actually felt bad for the ABIT people—it was a significant financial blow to them.

ABIT never recovered from the losses and went under in 2005.

[MarcoPajotter]

Hi,

Thanks every one for the posts and the info,
I gone open the PowerSupply case, and check all the capacitors first.
So, after that, I can see what happens inside when starting up.

In the time I used the apple II (1980...), we had have 220 VAC, today we have 240 VAC ...


- Q) I found an old 6502 cpu who runs on 4MHz.
Is here someone who upgraded his AppleII in clockspeed ?
And can it be done ?
I remember that the screen frequency was based on the CPU clock ...


greetings,
marco

PS: how can I use an image on this forum ?
I tried to use img.../img, but I receive an error message.

[BigEd]

You can attach an image file (and can choose to display it inline)

[BillO]

You can just remove the rifa for now and order a modern 0.1uF "X" type capacitor to replace it.

There is a small electrolytic that sits very near a heatsink somewhere near the middle of the power supply, that very often goes bad. This could be restricted to only some models of the PS, but it has been bad in every one I have repaired. Sorry I can't be more exact right now, but it's a fairly obvious situation and should not be that hard to find. Simply replace any really small electrolytic caps that are quite close to heatsinks. Use the highest temperature one you can find.

MarcoPajotter wrote:

- Q) I found an old 6502 cpu who runs on 4MHz.
Is here someone who upgraded his AppleII in clockspeed ?
And can it be done ?
I remember that the screen frequency was based on the CPU clock ...

I honestly do not think this can be done. A lot of things would need replacing including memory and much of the logic. There used to be accelerators available that "replace" the NMOS 6502 with a CMOS 65C02 and faster memory. They buffered everything and communicated with the Apple II bus at the old speed. Here is a modern example that uses the 65816 and allows access to 16 bit mode: https://www.reactivemicro.com/product/u ... celerator/. A lot cheaper and simpler than hacking up an increasingly valuable old computer.