Apple ][ clone incoming... What to do the first startup??

[penguin86]

As the title says, the next week I'll acquire an Apple ][ clone... I know clones are not so important, but I can't afford an original Apple ][
Btw, I read in some other posts that isn't safe to turn on directly, due to capacitators "unforming". Well, I read the linked document (http://www.nmr.mgh.harvard.edu/~reese/electrolytics/#rebuild) but I didn't understand exactly what to do (due electronic and english incompetence).
1) What is exactly a Variac? Where can I find an howto?
2) Where must I connect the Variac? To the single capacitator? Or to the power adapter?
Thanks for your help :-D
Daniele

 

[Sharkonwheels]

I think at some point, some people mentioned making an outlet fed by a dimmer switch, and to slowly bring up the voltage, but I have heard others say no...

I think some of the folks that work with the old time gear can better answer that question, like Billdeg, Erik, and Andrew Lynch..


T

 

[Micom 2000]

Aother old method was to test it using a 100w light bulb in circuit. Any over-amperage blows the bulb before any damage can happen.

Lawrence

 

[penguin86]

I think at some point, some people mentioned making an outlet fed by a dimmer switch, and to slowly bring up the voltage, but I have heard others say no...

I think some of the folks that work with the old time gear can better answer that question, like Billdeg, Erik, and Andrew Lynch..


T

Uhm... I think I'll have to find a circuit plan... Thanks anyway.

Aother old method was to test it using a 100w light bulb in circuit. Any over-amperage blows the bulb before any damage can happen.

Lawrence

Uhm... very interesting and absolutely not stupid! I think I'll do this
Just to be a little more safe...
Thanks

 

[Floppies_only]

I think at some point, some people mentioned making an outlet fed by a dimmer switch, and to slowly bring up the voltage, but I have heard others say no...

A variac accomplishes the same thing as a dimmer switch by a different means. A variac is a more substantial piece of equipment, about the size of a lunch box sitting on one end.

If you can't afford a variac, please your system by purchasing brand new capacitors and installing them in the power supply. It will probably cost about thirty dollars to buy a soldering iron (learn how to solder off of the internet before you do it), solder, and replacement capacitors. They will probably be electrolytic capacitors, so they have to be installed positive side to positive circuit board trace. You can learn how to tell what kind of capacitor it is and how to install it online.

On Monday I will look for websites to tell how to do all of this. Alternatively, if there are any TV repair shops in your area, they might install new capacitors for a slightly higher price.

Sean

 

[MikeS]

Just a word of caution:

The Variac/Lightbulb/Dimmer method of "soft"-powering up is used with linear supplies (big,heavy transformers and BIG electrolytic caps). It's not very effective with switchers like those in Apple clones, PCs etc., and can in fact damage some of those supplies.

m

 

[NobodyIsHere]

Hi,
I agree with Mike. I have used Variacs for restoring old linear power supplies to reform their capacitors. Switching power supplies is a whole different issue and I don't think the variac or light bulb trick will work for you.

As a work around, I'd get some scrap/dead equipment or fashion a power supply load and test the power supply with it. Some times a light bulb will serve as a good current limiting dummy load.

Best of luck with your project!

Andrew Lynch

 

[Druid6900]

I don't know, but, I've never had caps blow on anything I've ever got or worked on. I know it's happened to several people here and it may be limited to linear supplies.

If something ain't broke, don't fix it because, if you screw with something long enough, you WILL break it.

Turn it on. If something blows, replace it, if not, don't worry about it. There are very few circumstances under which a switching supply, even if it went super-nova, would damage anything else and popping caps isn't one of them.

 

[penguin86]

Wow! So much answers!!

A variac accomplishes the same thing as a dimmer switch by a different means. A variac is a more substantial piece of equipment, about the size of a lunch box sitting on one end.

If you can't afford a variac, please your system by purchasing brand new capacitors and installing them in the power supply. It will probably cost about thirty dollars to buy a soldering iron (learn how to solder off of the internet before you do it), solder, and replacement capacitors. They will probably be electrolytic capacitors, so they have to be installed positive side to positive circuit board trace. You can learn how to tell what kind of capacitor it is and how to install it online.

On Monday I will look for websites to tell how to do all of this. Alternatively, if there are any TV repair shops in your area, they might install new capacitors for a slightly higher price.

Sean

Thank you, btw I have some basic knowledges in electronic... I'm able to solder (even if I do it rarely ).
But, isn't enought to replace only swollen capacitators? (if I'm not wrong it's the sign the capacitator is at end of it's life...)

Just a word of caution:

The Variac/Lightbulb/Dimmer method of "soft"-powering up is used with linear supplies (big,heavy transformers and BIG electrolytic caps). It's not very effective with switchers like those in Apple clones, PCs etc., and can in fact damage some of those supplies.

m

Uhm... it's logic... switching supplies does work in a big range of tension (usually 110-230v...). So soft-powering up is useless...

Hi,
I agree with Mike. I have used Variacs for restoring old linear power supplies to reform their capacitors. Switching power supplies is a whole different issue and I don't think the variac or light bulb trick will work for you.

As a work around, I'd get some scrap/dead equipment or fashion a power supply load and test the power supply with it. Some times a light bulb will serve as a good current limiting dummy load.

Best of luck with your project!

Andrew Lynch

So you propose to unplug lo-voltage lines from the PC and try only the power supply with a lamp? I think it's a good compromise... :D

I don't know, but, I've never had caps blow on anything I've ever got or worked on. I know it's happened to several people here and it may be limited to linear supplies.

If something ain't broke, don't fix it because, if you screw with something long enough, you WILL break it.

Turn it on. If something blows, replace it, if not, don't worry about it. There are very few circumstances under which a switching supply, even if it went super-nova, would damage anything else and popping caps isn't one of them.

Well, I like this solution... But to make a map of the condenser's values should be fine (if a condenser pops i can't read its value...).

So this is the way I'll take:
1) Condenser value mapping
2) Turn on with a lamp in the exit of power supply
3) Turn on with the pc
And, obvuously, crossed fingers
(Uhm... do you use to say this? Or it's only an Italian proverb? :-D )


Thanks very much to all of you!
Daniele

 

[NobodyIsHere]

Wow! So much answers!!



Thank you, btw I have some basic knowledges in electronic... I'm able to solder (even if I do it rarely ).
But, isn't enought to replace only swollen capacitators? (if I'm not wrong it's the sign the capacitator is at end of it's life...)



Uhm... it's logic... switching supplies does work in a big range of tension (usually 110-230v...). So soft-powering up is useless...



So you propose to unplug lo-voltage lines from the PC and try only the power supply with a lamp? I think it's a good compromise... :D

Yes, I recommend disconnnecting or removing the power supply entirely and testing it separately. You'll have to attach it to a load or the switching PS wont even start up properly usually even if it is working.

The key is to excite the power supply and get it working, then test its output to ensure it is in the correct ranges. It doesn't have to be dead on 12v 5v or whatever but it should be close within a few percentage.

I have found dead equipment to be sufficient loads such as a scrap drive or motherboard. If none of those are available, try making a load from a low wattage incandescent light bulb (25 to 40W or less) to limit current flow.

If you test the PS with your new Apple II clone as the "dummy load" and the PS is dangerously malfunctioning, you may end up destroying the equipment. This happens -- please believe me. Maybe not often but enough that a little precaution is worth the effort.

Please don't use your valuable and rare motherboard as a piece of PS test equipment when a junky old broken CD-ROM or dead 3.5" floppy drive will work just as well.

Thanks and good luck!

Andrew Lynch

Well, I like this solution... But to make a map of the condenser's values should be fine (if a condenser pops i can't read its value...).

So this is the way I'll take:
1) Condenser value mapping
2) Turn on with a lamp in the exit of power supply
3) Turn on with the pc
And, obvuously, crossed fingers
(Uhm... do you use to say this? Or it's only an Italian proverb? :-D )


Thanks very much to all of you!
Daniele

 

[Druid6900]

I suppose he could chop up a PC type extender or splitter and then stuff the wires in the Apple II PSU power connector, but, that may be as dangerous as just flipping the switch. A little strain and a stray wire and there WILL be capacitors popping.

Just as a test, I just went downstairs and brought up 6 Apple II type PSU, stripped a molex 4 pin and stuffed and taped the wires into one of the connectors. I hooked it up to a scrap CD-ROM and flicked the switch. No boom. Voltages stable.

Second PSU - results the same.

Third PSU - results the same.

Now, some of these supplies haven't been plugged into anything in 20 years or more.

I will test the other 3 and report back tonight.

Until then, YMMV.

And, yes, people cross their fingers over here too

UPDATE: PSU units 4, 5 & 6 all powered up correctly and a loaded voltage test showed that all six supplies were within specs (used a modified splitter to two CDROMs and measured voltages on the first 3 PSUs as well).

 

[MikeS]

I'm inclined to agree with Druid *and* Andrew; the chances that the PS will fail in a way that damages the connected system are pretty small, but it can't hurt to test it (carefully) with a dummy load of some kind; much more likely that it won't start up at all.

And of course it's almost as likely to fail after all your careful testing etc., when you next turn on the computer a few days or weeks later.

Some people can even cross their toes...

m

 

[penguin86]

First of all, thanks very much for your answers
Well, I found a good car lamp (20w, so about 2Ah @ 12v) and I have a digital multimeter. When the machine will arrive (I hope before the end of this new week... ) I'll test the power supply and (if working) try to turn on the machine.
And, of course, I'll place here some photos
Thanks, guys!
Bye!
Daniele

 

[Floppies_only]

Wow! So much answers!!



Thank you, btw I have some basic knowledges in electronic... I'm able to solder (even if I do it rarely ).
But, isn't enought to replace only swollen capacitators? (if I'm not wrong it's the sign the capacitator is at end of it's life...)

I have to admit that I don't know a lot about this. But the two websites I read today said that you can blow a cap before it shows signs of swelling.

I am just wondering, when did the switching power supplies come into vogue in computers? I seem to remember that an IBM PC (5150) has that, but is that right?

Sean

 

[penguin86]

I have to admit that I don't know a lot about this. But the two websites I read today said that you can blow a cap before it shows signs of swelling.

I am just wondering, when did the switching power supplies come into vogue in computers? I seem to remember that an IBM PC (5150) has that, but is that right?

Sean

Interesting question... The oldest computer I had was a Commodore 64, but I didn't open its power supply. The oldest I opened was an 8088 and it has an half-size switching power supply similar to Macintosh LC's one.
Well, we will know it soon (I hope...)

 

[MikeS]

They went both ways back in the 80's; Commodore PETs, VICs, C64s etc. all had linear supplies while Apple used switchers exclusively AFAIK. Most S-100 systems used massive linear supplies while the PC and clones generally used switchers (with a few exceptions like the Sanyo MBCs for example).

Consumer electronics (VCRs etc.) also used both for quite a while.

Today you rarely see line-frequency transformers (linear supplies) any more; even cheap little AC adapters are switchers today.

m