Apple II, DIY, IIgs, Retro, Vintage

Tuning Vintage Hardware

August 20, 2018

So far, in my experience collecting and restoring vintage Apple and Mac computers, I have found that the overwhelmingly vast majority of this equipment works as well now as it did the day that it was made, without any real work beyond a good cleaning. Whenever I pick up a new box of someone’s vintage Apple rubbish, I fully expect that anything that is not working can be fixed relatively easily, and that there will likely not even be anything wrong with it in the first place. Of course, you learn to notice the warning signs, water stains, leaky caps, the smell of burned electronics, etc., before you even leave the scene. You drive home creating a hypothesis as to what will need to be done to restore this or that. Sometimes you are correct, and sometimes you missed something and are way off. Sometimes, there are components that needs replaced, almost always there is some deep cleaning involved, and yet sometimes, there is some fine-tuning of some variable¬†components that is necessary.

Enter the latest hardware lot that I picked up. It all looked like it had a brief surface-level cleaning, and I had no idea what I was getting into. For reference, the hardware list I recently picked up is as follows:

  • (1) Apple II+ with 16k language card, Parallel port card, and a Disk ][ interface card.
  • (1) Disk ][ floppy drive.
  • (1) A2M6014 AppleColor RGB Monitor (to use with my IIgs.)

I already published a blog post a week ago on restoring the II+. I had to pull each IC and clean all of the corrosion off of the pins, replace the power supply, and replace a capacitor that was missing a leg. After that, it works like new again and is quite a fun machine. I had to adjust the centering rings on the A2M2010 monitor that I am using on it, but as far as I can tell, this is normal when using a II+ and that monitor.

After this job was complete, I decided to tackle the A2M6014 RGB monitor. I hooked it up to my IIgs and the image was so fuzzy and out of focus that I felt like I was reading the screen underwater.

Wow, did it look bad! I read about adjusting the focus on this monitor and luckily, there are two potentiometers hidden inside the unit for adjusting the focus and intensity. They are not accessible from the outside because of their proximity to some high voltage components of the CRT. So, I opened up the monitor by removing the back cover and had myself a look inside.

DISCLAIMER: THERE IS ENOUGH VOLTAGE TO KILL YOU INSIDE OF A CRT MONITOR. KNOW WHAT YOU ARE DOING BEFORE YOU DO IT.

Here, you can see the two black knobs attached to the potentiometers that I am speaking of. The idea here is to center the two dials on the side of the monitor, contrast and brightness, and then use these two focus and intensity knobs to clean up the picture as much as possible, moving the brightness and contrast controls away from center as little as possible. This will give you more adjustment in either direction with the brightness and contrast controls once you replace the back cover. With just a little bit of adjustment, I had the monitor focused, the intensity set and the brightness and contrast working well. I then looked around inside the monitor and found that there were adjustments for each of the three colors independently – red, green and blue. I decided that while I had the cover removed, I would check the levels of each color. An Apple IIgs has a great Control Panel option for displaying colors. If you press CTRL-OPEN APPLE-ESC, you will see a menu, with a choice for a Control Panel, and if you choose ‘Control Panel’, then choose ‘Display’, you will see another menu where you can cycle through the different background colors. The default color is Medium Blue. With the monitor still exposing it’s innards, I cycled through the different colors one at a time, turning each dial to tune in the colors, so that black was black, medium blue was medium blue, brown was brown, pink was pink, etc. This took a bit to figure out, but within about 15 minutes, start to finish, I had this monitor looking like it did fresh out of the box.

With the monitor tuned up, I was not disappointed. The colors looked correct, the contrast and focus were great ! While I was using the RGB->SCART->HDMI solution, there was an annoying visual artifact when displaying certain colors, most notably the default background of GS/OS. Now that I am using the proper CRT monitor, that issue is gone! This monitor is reportedly too slow to see that artifact and smoothes it right out. It’s the right tool for the job. The IIgs was not meant to be converted from RGB to SCART to HDMI. Don’t get me wrong, that solution has it’s advantages, and I cannot wait to see how John Brooks new HDMI interface card is going to work when it releases, but this is the way that Apple designed the IIgs to be seen, on a A2M6014 CRT monitor. And it looks great!

After this, I decided to test the Disk ][ drive that came with the II+ and see if it would read and write to a disk, or if it needed cleaned, or even more. I placed a disk into that drive, placed the DOS 3.3 Master disk into drive one, and booted the computer. It booted, loaded integer rom, and then I typed ‘catalog s6,d2’ and pressed return. The drive light lit up, the motor spun to life, and then it promptly stopped again. The screen read ‘I/O error’. I opened up the drive and using some 91% iso alcohol, I cleaned the drive’s heads. I allowed that to fully dry, powered the computer back up and tried again – I/O Error. Dang! What do I do now? I could tell that the motor was working, I could tell that the head mechanism was moving and attempting to read the disk, so what could the issue be? I searched the Internet and found some good info on tuning Disk ][ drives. The first article I read suggested using a program called Locksmith. It was written for an Apple IIc drive, but I figured the same principals applied. I downloaded a copy of Locksmith 6 from Asimov, wrote it to disk with my IIe and ADTPro, and with this disk in drive one, I booted the II+. I ran the speed test first, because I figured this would be the simplest thing to adjust without an oscilloscope (I do not have one yet.) and right away I could see that the drive speed was too fast.

I looked everywhere for the speed adjustment and just could not find it. The insides of a Disk ][ drive do not resemble the Iic drive in the article that I read at all. I could not see any adjustments on the motor itself or anywhere near it. I did find while searching around that the write-protect switch was a bit sticky on this drive. I cleaned it with the iso alcohol and made sure it was working freely while I was in there. But how do you adjust the speed on this drive? I went back to google and finally found a SAMS manual for the Disk ][ drive. This guide shows a picture of the speed adjustment screw. It is on the circuit board that is in the back of the drive, which I found out later is called the ‘motor control card.’ Here is the labeled picture of the Motor Control Card from the SAMS manual and my picture of the adjustment screw, accessed from the right side when looking at the face of the drive.

I reran the speed test in Locksmith and adjusted the drive to be within the -5 to 0 that the manual recommended.

I grabbed my DOS 3.3 Master disk and my test floppy, inserted them into the two drives again and repeated m read test – It worked! Drive 2 was now able to catalog a disk! I decided to try a write before I signed off, so I booted from ADTPro disk and chose Audio from the main prompt. Once booted up, I chose format from the menu. ADTPro read disk one, then read disk two. I chose disk 2 and proceeded to format it. The format finished successfully! Sweet! My drive will now read and write successfully!

One of the most rewarding feelings that I have found in life is repairing or restoring something that was no longer working properly, and making it work like new again. None of the equipment that I fixed here was actually broken. It all just needed a good cleaning, some fine-tuning and adjustments, and some old fashioned TLC. Time will tell, but I believe that this equipment will still be working for several years to come.

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