hello

I recently came in contact with a iigs and was curious if anyone had a circuit layout or schematic diagram for recapping. sorry for my ignorance because this is my first repair. the model of psu is astec 6990126. i believe my motherboard is a Rom3. also could someone give an opinion whether or not I should tear into the apple color rgb crt monitor. I have no experience with those either but from what I've saw people usually test them and then fix accordingly. I haven't actually plugged the monitor or the iigs for fear of burning the power supply or monitor circuit boards.

thanks.

Logan T wrote:
>
> them and then fix accordingly. I haven't actually plugged the monitor or
> the iigs for fear of burning the power supply or monitor circuit boards.
>

Unless it was stored for many years in some hostile environment, I think
you'll find the Apple IIgs is among the most reliable Apple II models ever
produced, especially the ROM3 which you have.

Here is a site with a lot of documentation and other info:
http://www.apple-iigs.info/home.php

Here are schematics for ROM 3:
https://downloads.reactivemicro.com/Apple%20II%20Items/Hardware/IIgs/Schematic/

The book mentioned in my signature below has a lot of general information
about the entire Apple II family. It doesn't have a lot of hardware repair
information, but you might find it a good source for many other aspects of
the Apple II.

--
]DF$
The New Apple II User's Guide:
https://macgui.com/newa2guide/

On Thursday, January 20, 2022 at 9:42:16 PM UTC-5, D Finnigan wrote:
> Logan T wrote:
> >
> > them and then fix accordingly. I haven't actually plugged the monitor or
> > the iigs for fear of burning the power supply or monitor circuit boards..
> >
> Unless it was stored for many years in some hostile environment, I think
> you'll find the Apple IIgs is among the most reliable Apple II models ever
> produced, especially the ROM3 which you have.

Unlike machines from the 90's or later, I've never had to re-cap an Apple II let alone a IIgs. The worst thing I've seen happen is that the RIFA blows in the power supply which lets out some awful smoke, but the machine still works without it (the purpose is to reduce radio interference). The RIFA caps are easy enough to replace, though if you're looking for a more complete solution, you can buy brand new replacement power supplies from Reactive Micro.

Don't tear the machine apart until something goes wrong with it. However, make sure that the battery is in good condition - the ROM 03 has a socketed battery whereas earlier ones were soldered barrels which needed to be clipped.

Good luck!

Logan T <logan07night@gmail.com> wrote:
> I recently came in contact with a iigs and was curious if anyone had a
> circuit layout or schematic diagram for recapping. sorry for my ignorance
> because this is my first repair. the model of psu is astec 6990126. i
> believe my motherboard is a Rom3.

Are you sure it needs recapping? The most I've needed to do to a IIGS
motherboard is replace the dead battery. If it's a ROM 3, it's easily
replaced with a 1/2 AA lithium primary battery, such as this:

https://amzn.to/3GQUwB3

If it's a ROM 01, you'll need to cut out the original hardwired battery.
You can then put in a holder to facilitate easier replacement in the future,
such as this one that takes the same 1/2 AAs that the ROM 3 uses:

https://www.thingiverse.com/thing:3407875

If it's a dead power supply (you didn't say if it's the motherboard or the
power supply), my understanding is that it's the line-filter capacitors
(yellowish, rectangular, with foil wrapped up inside) that tend to go bad if
anything goes bad. I think there's one that'll keep the supply from firing
up if it goes bad; removing it or replacing it is supposed to get things
working again.

As for the electrolytics, these power supplies were built ~20 years before
counterfeit electrolytic capacitors were even a thing, so unless you've
confirmed that they're leaking or the power supply is not working, I would
be inclined to leave them alone.

--
_/_
/ v \ Scott Alfter (remove the obvious to send mail)
(IIGS( https://alfter.us/ Top-posting!
\_^_/ >What's the most annoying thing on Usenet?

On Friday, January 21, 2022 at 2:15:43 PM UTC-6, sc...@alfter.diespammersdie.us wrote:
> Logan T <logan0...@gmail.com> wrote:
> > I recently came in contact with a iigs and was curious if anyone had a
> > circuit layout or schematic diagram for recapping. sorry for my ignorance
> > because this is my first repair. the model of psu is astec 6990126. i
> > believe my motherboard is a Rom3.
> Are you sure it needs recapping? The most I've needed to do to a IIGS
> motherboard is replace the dead battery. If it's a ROM 3, it's easily
> replaced with a 1/2 AA lithium primary battery, such as this:
>
> https://amzn.to/3GQUwB3
>
> If it's a ROM 01, you'll need to cut out the original hardwired battery.
> You can then put in a holder to facilitate easier replacement in the future,
> such as this one that takes the same 1/2 AAs that the ROM 3 uses:
>
> https://www.thingiverse.com/thing:3407875
>
> If it's a dead power supply (you didn't say if it's the motherboard or the
> power supply), my understanding is that it's the line-filter capacitors
> (yellowish, rectangular, with foil wrapped up inside) that tend to go bad if
> anything goes bad. I think there's one that'll keep the supply from firing
> up if it goes bad; removing it or replacing it is supposed to get things
> working again.
>
> As for the electrolytics, these power supplies were built ~20 years before
> counterfeit electrolytic capacitors were even a thing, so unless you've
> confirmed that they're leaking or the power supply is not working, I would
> be inclined to leave them alone.
>
> --
> _/_
> / v \ Scott Alfter (remove the obvious to send mail)
> (IIGS( https://alfter.us/ Top-posting!
> \_^_/ >What's the most annoying thing on Usenet?

On Friday, January 21, 2022 at 2:15:43 PM UTC-6, wrote
> Logan T wrote:
> > I recently came in contact with a iigs and was curious if anyone had a
> > circuit layout or schematic diagram for recapping. sorry for my ignorance
> > because this is my first repair. the model of psu is astec 6990126. i
> > believe my motherboard is a Rom3.
> Are you sure it needs recapping? The most I've needed to do to a IIGS
> motherboard is replace the dead battery. If it's a ROM 3, it's easily
> replaced with a 1/2 AA lithium primary battery, such as this:
>
> https://amzn.to/3GQUwB3
>
> If it's a ROM 01, you'll need to cut out the original hardwired battery.
> You can then put in a holder to facilitate easier replacement in the future,
> such as this one that takes the same 1/2 AAs that the ROM 3 uses:
>
> https://www.thingiverse.com/thing:3407875
>
> If it's a dead power supply (you didn't say if it's the motherboard or the
> power supply), my understanding is that it's the line-filter capacitors
> (yellowish, rectangular, with foil wrapped up inside) that tend to go bad if
> anything goes bad. I think there's one that'll keep the supply from firing
> up if it goes bad; removing it or replacing it is supposed to get things
> working again.
>
> As for the electrolytics, these power supplies were built ~20 years before
> counterfeit electrolytic capacitors were even a thing, so unless you've
> confirmed that they're leaking or the power supply is not working, I would
> be inclined to leave them alone.
>
> --
> _/_
> / v \ Scott Alfter (remove the obvious to send mail)
> (IIGS( https://alfter.us/ Top-posting!
> \_^_/ >What's the most annoying thing on Usenet?
hello
thanks everyone for tips and info. my iigs is sitting in front of me and I'm very new to all this.
I'm not sure if I replied to all the above I hit post and it disappeared so forgive me if that happened.
but another question I had was wether anyone had some options on floppy disk writing software for windows preferably about win7 and up. I am currently running windows but if anyone also has some Linux software that's also welcome, ease be aware I'm not experienced in command line yet but irrelevant. this way I would be able to download disk or such images for my iigs from web archives and write them to blanks instead of finding and buying prewritten software or programs from eBay or such. hope my idea is clear here
thanks

You shouldn't have to recap anything on the motherboard. Inside the PSU the Dreaded RIFA capacitors will blow eventually. Not all GS PSU have RIFA filter capacitors though. They are half inch long rectangles near the AC input lines. If they look like clear epoxy on the outside, and they are cracked, delete them immediately.

There is a debate about whether you really need to replace them or not. New ones are cheap. But the power supply will work without them at the cost of more electrical noise, and maybe making the rest of the PSU more susceptible to line noise coming in.

The other capacitor that died on me (but on only one PSU) is a 220 mF in the middle of the circuit board. That was a standard electrolytic, and it was obviously dead. The label was just sitting there and goo had leaked out. A good clean up and replacement and it worked fine.

Youtube has several videos about recapping things, don't get too carried away. The little .47 uf surface mount electrolytic capacitors used on many old macs are very problematic now. The radial and axial capacitors used on Apple II's seem to be more robust.

But the RIFA caps will die, and it stinks to high heaven when they do. And they make a mess.

my rifa according to what u said looks like it might be bad. for what I am going to use this iigs for, at least to start with is just learning the basics, so I believe electrical noise probably wouldn't hurt me unless it actually is bad enuf to damage the iigs motherboard which I doubt. ok Im acting like I know how psus work but I don't think that that will be a problem. ther is a big black 330uf in the center on my psu, understandably ther are different models of psus used so I'm not sure if this is what you are referring to in "is a 220mf"but this one doesn't look leaking. in fact all the caps look all right to my knowledge. I want to boot up as soon as possible and let u all know my results

Logan T <logan07night@gmail.com> wrote:
> my rifa according to what u said looks like it might be bad. for what I
> am going to use this iigs for, at least to start with is just learning
> the basics, so I believe electrical noise probably wouldn't hurt me
> unless it actually is bad enuf to damage the iigs motherboard which I
> doubt. ok Im acting like I know how psus work but I don't think that that
> will be a problem. ther is a big black 330uf in the center on my psu,
> understandably ther are different models of psus used so I'm not sure if
> this is what you are referring to in "is a 220mf"but this one doesn't
> look leaking. in fact all the caps look all right to my knowledge. I want
> to boot up as soon as possible and let u all know my results
>

Don’t re-cap it. “If it ain’t broke, don’t fix it!”

What folks are referring to as “the RIFA cap” is an “X2” type of capacitor
designed to go across the AC line to attenuate RF noise, both incoming and
outgoing, and incoming spikes. Its failure mode is shorting, followed
milliseconds later by rupture and emission of a revolting vapor. If you
can stand to be within a foot of your power supply, your line filter
capacitor is fine.

Wholesale capacitor replacement without any demonstrated need is a peculiar
superstition that is mystifying to electronic technicians.

--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com

Michael J. Mahon <mjmahon@aol.com> wrote:
> Wholesale capacitor replacement without any demonstrated need is a peculiar
> superstition that is mystifying to electronic technicians.

I have a 70-year-old RCA AM radio that I went through maybe 25 or so years
ago and replaced all of the waxed paper capacitors with metalized film
capacitors, as those are a known point of failure for devices that use them.
I don't recall if it used any mica capacitors, but if it did, I would've
replaced them as well because you might as well while you're in there.
There was also a two-part electrolytic capacitor that clearly wasn't working
(someone else had hacked in two separate capacitors, one of which had a
loose lead flapping in the breeze), and one or two tubes tested weak.

These changes turned a non-working radio into a radio that still works
today, and whose only likely failure mode at this point is a tube failure.

Shotgun capacitor replacement as a practice may have come from replacing
classes of parts known to be troublesome, like paper-dielectric capacitors.
It might not always be appropriate for newer equipment, especially if it's
known to be in good working order.

--
_/_
/ v \ Scott Alfter (remove the obvious to send mail)
(IIGS( https://alfter.us/ Top-posting!
\_^_/ >What's the most annoying thing on Usenet?

<scott@alfter.diespammersdie.us> wrote:
> Michael J. Mahon <mjmahon@aol.com> wrote:
>> Wholesale capacitor replacement without any demonstrated need is a peculiar
>> superstition that is mystifying to electronic technicians.
>
> I have a 70-year-old RCA AM radio that I went through maybe 25 or so years
> ago and replaced all of the waxed paper capacitors with metalized film
> capacitors, as those are a known point of failure for devices that use them.
> I don't recall if it used any mica capacitors, but if it did, I would've
> replaced them as well because you might as well while you're in there.
> There was also a two-part electrolytic capacitor that clearly wasn't working
> (someone else had hacked in two separate capacitors, one of which had a
> loose lead flapping in the breeze), and one or two tubes tested weak.
>
> These changes turned a non-working radio into a radio that still works
> today, and whose only likely failure mode at this point is a tube failure.
>
> Shotgun capacitor replacement as a practice may have come from replacing
> classes of parts known to be troublesome, like paper-dielectric capacitors.
> It might not always be appropriate for newer equipment, especially if it's
> known to be in good working order.
>

I certainly agree, Scott, for older (often vacuum tube) equipment. ;-)

I was referring to the emerging habit of treating 1980+ equipment like
1935+ equipment.

Nice work restoring your radio—a standard AC/DC 5-tube superhet, no doubt.
The paper capacitors were a leakage problem even in their day! And there
are two small mica capacitors in each IF transformer, sharing a single
sliver of mica. And that was a troublesome design flaw: in humid
conditions, dust and other contaminants would accumulate on the mica and
create a leakage path from the plate side of the transformer and the grid
side of the following stage, disabling the AGC and making the radio
unlistenable.

I’d expect most other mica caps to be quite reliable, as long as they are
sealed and uncontaminated.

--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com