Apple 2+ VIDEO ISSUE WITH 16K CARD

5 posts / 0 new
Last post
Offline
Last seen: 2 months 1 week ago
Joined: Jul 24 2021 - 13:21
Posts: 9
Apple 2+ VIDEO ISSUE WITH 16K CARD

I have a machine that hasn't been powered in years.  Powered up first time yesterday.  Fully bots up  floppy works. 

With the 16k card plugged into the memory socket the display is garbled.  You can see where characters are supposed to be but unreadable.  Disk boots still..  Without the 16k it boots cleanly 95% of the time but still gives me that messed display once in a while.  So i don't think it is 100% the 16k card but noise or something.  I have a tested card coming from ebay next month.   I pulled the ram chips out of the 16k card  same result.  I have swapped most of the 74ls chips on it same result.  

Also the keyboard seems to need a good cleaning. Some keys repeat, others need to be hit 5x to get it to register.  Any good suggestion on how not to mess it up more? 

 

Offline
Last seen: 2 months 1 week ago
Joined: Jul 24 2021 - 13:21
Posts: 9
update with pictures
Offline
Last seen: 2 months 1 week ago
Joined: Jul 24 2021 - 13:21
Posts: 9
Well looks like a few

Well looks like a few separate issues. 1.  The 16k card came in today and I can now boot prodos and see all 64k. 2.  I can't format a disk but I can read them.  Clicking noises then an io error.  Time to take the drive apart and check speed I guess.   And wipe the heads. 3.  I can't get aptpro to bootstrap though the cassette in. I get about 90% sent then The apple gives a ERR. 4.  The video issue looks like a bad port on the apple or an issue with the composite to HDMI converter or a grounding issues.   If I barely plug the video cable in I get a sharp clean picture. If I put it in all the way I get the vertical lines.  It will be nice and clear then I do a disk access and I have to play with the plug to get the screen back.  I am guessing the blue text is from the HDMI converter unless the colour brust blocking transistor is not working.   

 

CheshireNoir's picture
Offline
Last seen: 6 hours 44 min ago
Joined: Dec 28 2019 - 05:20
Posts: 128
Clean (or replace) the composite connector

Those Composite connectors are usually pretty crusty by now. I had all sorts of fun video issues myself.

If you're not aware, there are a couple of adjustable pots on the motherboard you can use to "tune in" the video signal a little bit. Right hand side 3/5 the way to the back from memory.

To clean the connector, I'd suggest gently cleaning off the outside with either an ink eraser or a fibreglass pen. You're trying to remove oxidation, not the plating :-)

A bit of Deoxit (or your local equvelant) on a cotton bud stuffed down the center contact should help there.

If that still doesn't help, check for dry joints around the connector.

 

You can still buy replacement connectors, but they are no longer being produced "new" so are likely to be a dwindling resource.

https://www.digikey.com.au/products/en?keywords=36-902-ND%E2%80%8E

(Out at digikey although the do have a substitution part that might work)

 

Hope you get it top top and ship shape.

 

Cheers!

 

Chesh

Offline
Last seen: 2 months 1 week ago
Joined: Jul 24 2021 - 13:21
Posts: 9
Getting closer.  Adtpro works

Getting closer.  Adtpro works from one of my old windows tablet  doesn't work on my android or new pc.  

The video pin looks like it moves when I wiggle the connection.  Not sure if there is a cracked solder point or what.  Once I have everything working, I will pull the board to resolder it and clean the keyboard.  

 

 My biggest issue now is writing to the disk .  I have some old 3m dsdd disks that won't format .  I can't seem to save onto a formatted disk either.

 

I order some new dsdd disks from ebay to see if that helps but since I can't save a basic program on an existing disk worries me..

 

I scope the heads and it looks like data is  going to the write head.  I need to find my multi meter to test the head resistances according to the guide I found.  

 

 

 

Log in or register to post comments