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 Sync Issue | 135.9 KB |
Hello,
I have a replica with a sync issue. I have tested the computer with a couple monitors, an Apple Monitor II and a Sony SSM-125. The image below is the best sync picture that I was able to obtain. Does this look like a monitor issue or something with the computer?
Hi there,
let's first make sure there are no easy fixes:
1. Have you tried adjusting the potentiometer at D1? If set too low, the signal might be too weak for the monitor to sync. Turning the potentiometer to the right will increase signal strength.
2. If the monitor allows for horizontal/vertical hold adjustment, play with them to see if that makes a difference.
The video signal produced by the Apple-1 is not perfect, ie. not following the standard 100 percent (which is also the reason why most modern TVs will simply show nothing/garbage when you connect the Apple-1 using an HDMI adapter).
Hope that helps and Happy New Year!
Armin
Hello,
Happy new year to you as well!
I have adjusted D1 in the computer as well as V-Hold and H-Hold on the Sony monitor when attempting to get a good picture. I have done the same adjusting of D1 and V-Hold when testing with the Monitor II. The attached photo is the best output I was able to achieve.
https://www.applefritter.com/content/how-fix-nonstandard-apple-1-video
And tell us if it helped !
Regards,
Uncle Bernie
Thank you! I will familiarize myself with the documentation and add that to my project list.
One thing that does give me pause is that I did not have success with a Monitor II, which I believe I read here would work. I have also noticed from other videos that my display is reversed. I am seeing black text on a white background and others see white on black. If I adjust my brightness pots to see it this way I do not have discernable characters.
Any thoughts or insight would be greatly appreciated.
Can you post a (highres) picture of the terminal secion of your Apple-1 board, please?
edit: triple post
edit: triple post
Of course! I have split it into two photos.
T1.JPG
T2.JPG
... but most likely, reverse polarity of the video signal. Use an ohmmeter to verify (with power off) that the "ground" of your video plug is connected to the "ground" / 0V rail of your Apple-1 (Refer to the schematics). And then verify that the center contact of your video plug goes to the wiper of the 100 Ohm trim pot.
Sorry that I did not look at your screen photo earlier, as I was in a hurry.
Note that some monitors have inverted video modes but as you got the same issue with multiple monitors, it is unlikely that this is the reason.
- Uncle Bernie
Well.... I am glad that beginners are welcome here. The cable was wired incorrectly. I had purchased it instead of made it so I did not think to test that. Thank you. I was up and running with no issue.
Hi Tasa,
is the Apple-1 one of my replicas? And did you also buy the cable of me? Then a refund would be in order for the cable and I would be very surprised that it did not work as I personally test every component before I ship it. Are you absolutely sure you did not plug in the 4pin molex the wrong way (this can be done despite the bulge to prevent this).
Best
Armin
Hi Armin,
It is your replica, but I checked my records and the cable was from a different seller. I am certain of my plugging orientation, I tested to see if I did by chance go the other way and there was far more resistance than I would have pushed against.
Thank you!
Thanks for clarifying!
In post #13, 'tasa' wrote:
" I am certain of my plugging orientation, I tested to see if I did by chance go the other way and there was far more resistance than I would have pushed against. "
Uncle Bernie comments:
These connectors usually have a bulge or rim towards the end. This bulge is meant to mate with the "lip" of the pin header. There is a snap action and this prevents that the connector can vibrate loose. It also prevents easy removal. And it requires quite some force to plug in the cable.
But be aware that of connectors (headers and plugs) of different connector families are combined against the intent of the manufacturers, the insertion force may become excessive, or the connectors may not mate at all. I have found a combination for my kits from different connector families which has no snap action if the IDC plug is put in turned 180 degrees, which in this case is intentional - but the video cable to the IDC plug must then be soldered in as described in my posts here on Applefritter on the topic.
Never use excessive force. But observe what you have and how it might mate together.
I have a hunch that you were so afraid of the insertion force that you chose the easier way, which is turned 180 degrees, and then you got the inverse video.
To avoid, you can always pre-bend the "lip" on the header a little bit outwards, gently, just a little bit, the make the insertion and removal of the cable plug easier.
- Uncle Bernie