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Apple //gs restoration and AppleColor RGB (A2M6014X) monitor repair - advice very welcome!

raaahbin

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Oct 5, 2023
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4
My dad has been cleaning out his piles of hoarded things from over the decades as he prepares to move house, a task with which I've been helping a little, and as a result I've just inherited the Apple //gs Woz edition that we had when I was in high school. Unfortunately it has not been subject to complete hoarding, so there are some important things missing: a keyboard and mouse (replacements already ordered from ebay), all the software disks (I'm thinking of getting a Floppy Emu), and I'm not sure whether or not the hard disk that's been stored with it actually went with that computer (but see above re: Floppy Emu - we may just have to do without the original experience of physical disks). I'm looking forward to the project of getting it back in working order, and introducing my own kids to it as a retro gaming platform (and whatever else they want to try doing with it). At this stage, my plan is as follows:

- replace the clock battery (fortunately it has not leaked over the years, so it should be a straight remove-and-replace job - I already have the replacement)
- restore the PSU with a ReActiveMicro PSU kit (the original is probably ok, but I don't want to go to the effort of putting things back together just to have the PSU fail once it starts being used again)
- get the monitor working
- order a Floppy Emu, put it all together, start playing around with it

The observant among you might have noticed my throwaway line of "get the monitor working". I say that because when I plugged it in - just to test basic functioning of the CPU and monitor (nothing else connected) - I found that the monitor doesn't display anything. I can hear the monitor power on, and I noticed that a loose bit of tape was affected by the static charge on the screen, but the green light doesn't come on and nothing is displayed, regardless of how I move the brightness and contrast dials.

Now, I've done some searching around, and found a number of suggestions as to where to go from here. As someone who has built a few hobby electronic kits, but never repaired a TV or monitor before, I'd certainly appreciate the advice of people who have done it a lot. This reddit post (with no actual solution) seems to be identical in behaviour to what I'm seeing - although I never heard the popping sound they mention. I see specifically that they have already tried a full capacitor replacement using the console5 kit. I also found something from a different forum giving Apple // monitor repair advice, which talks about crystallised solder on the power supply board. The latter talks about it working for a period of time before going dark and the light going off, but perhaps in some cases - maybe with a fully broken solder joint - it would never properly power up, jumping straight to the failure mode. Any advice on that would be very welcome!

If I can't get the monitor working again at all, I'd be inclined to go down the route of installing a VidHD card. So far, my attempts to email enquiries about that card have not received responses - does anyone happen to know if those cards are still being made?
 

ajacocks

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Welcome to the forum @raaahbin .

Given that there is no power light, you probably have at least some cracked solder joints. Capacitor leakage is unlikely to cause that.

I would indeed go ahead and recap the monitor, given the high heat environment that all the internal components live in. Other than that, you can check the voltages on the various components of the monitor, particularly the B+ drive voltage. Here is a link to the manuals for the monitor:


As far as the VidHD goes, it doesn’t appear that they are available to purchase right now, due to component shortages. You might consider getting an RGB2HDMI adapter (Raspberry Pi Zero-based RGB converter). They do a really good job of straight conversion:


Here is a video showing how that adapter works:


Hope this helps!
- Alex
 

raaahbin

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Oct 5, 2023
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4
Thanks for that detailed advice! I might hold off on ordering the replacement capacitors until I see whether I can get the monitor to some degree of working - no point in having a fresh set of capacitors installed in a monitor that I'm unable to get displaying anything at all. I'm a bit hesitant about the installation involved in the RGBtoHDMI - would much prefer to go down the expansion card route than soldering a whole mess of wires to the underside of the motherboard, even if that means waiting a while for VidHD cards to become available (or I gather there may be something coming from ReActiveMicro). It's ok - this will be a long-term project, and it's good to know there's at least one non-composite option available if the AppleColor RGB never comes good.
 

cruff

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Dec 12, 2012
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395
Location
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You could test the PS with dummy loads for a while while you have it apart.
 

atariquest

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Jul 31, 2023
Messages
20
I have several Apple II 8-bit machines, but I have not used a IIGS since the late 80s in high school.

If I understand your post correctly, you are not certain of the IIGS is working. Does it show any sign of life like a light or beep when you turn on the power?

I do not thing you specified which monitor you have. RGB or composite?

Marvin
 

raaahbin

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Joined
Oct 5, 2023
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4
I have several Apple II 8-bit machines, but I have not used a IIGS since the late 80s in high school.

If I understand your post correctly, you are not certain of the IIGS is working. Does it show any sign of life like a light or beep when you turn on the power?

I do not thing you specified which monitor you have. RGB or composite?

Marvin
I'm pretty sure the IIgs is working - it beeps twice when powered on (one for the power-up, and one because I don't have any start disk connected to it). I have yet to try plugging in its composite out to an old TV, but I'm planning to do that. Still, I expect the IIgs is working ok - it's much more likely the monitor is not functioning, since the particular manner in which the monitor is not functioning is identical to what I have read elsewhere. It's the AppleColor RGB monitor, i.e. the correct original monitor for the IIgs.
 

atariquest

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Joined
Jul 31, 2023
Messages
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If you decide to work on the monitor, user ajacocks provided a schematic. Typically a schematic like this will be included inside a service manual that gives details for the theory of operation, parts lists, and test point values. Perhaps you can find a service manual. On the schematic you will see rectangles labeled "TP-n". Those are the test points. Using these points you can work your way across the PCB looking for readings that are out of spec to fix issues. For most points you will need an oscilliscope.

Be careful working inside the monitor. There are two areas that are dangerous: mains voltage to the power supply (110v AC), high voltage from the flyback transformer to the CRT (10,000+v DC). Keep in mind that the CRT may retain high voltage even after the unit is turned off and unplugged. Some monitors have bleed resistors to discharge the CRT, but I never trust them.

Marvin
 

raaahbin

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Joined
Oct 5, 2023
Messages
4
If you decide to work on the monitor, user ajacocks provided a schematic. Typically a schematic like this will be included inside a service manual that gives details for the theory of operation, parts lists, and test point values. Perhaps you can find a service manual. On the schematic you will see rectangles labeled "TP-n". Those are the test points. Using these points you can work your way across the PCB looking for readings that are out of spec to fix issues. For most points you will need an oscilliscope.
Since I don't have an oscilloscope - or the skills to use one or know what I'm looking for across given test points - I'll just be looking for bad solder joints, damaged components, and/or any obvious breaks in the circuitry that can be found with a multimeter. Working inside the monitor while powered on is not within my skill set, so if that's what it takes I'll either need to find someone local who specialises in such things, or wait for an alternative such as the VidHD to become available.
Be careful working inside the monitor. There are two areas that are dangerous: mains voltage to the power supply (110v AC), high voltage from the flyback transformer to the CRT (10,000+v DC). Keep in mind that the CRT may retain high voltage even after the unit is turned off and unplugged. Some monitors have bleed resistors to discharge the CRT, but I never trust them.
Thanks - I've read up on safety precautions for opening and working inside a monitor (which I intend to follow), as well as watching some videos of people discharging the CRT itself in case of retained voltage, so as long as I stick to working on it while unplugged and follow those steps as well, I think I should be OK. That may limit my ability to repair it, but if the skills I have aren't what it needs, I'll set about finding someone who does have the requisite skills.
 
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