hello all and a plea for help on a II Europlus :)

2 posts / 0 new
Last post
Offline
Last seen: 1 week 3 days ago
Joined: Nov 2 2019 - 06:07
Posts: 1
hello all and a plea for help on a II Europlus :)

Hello all.

Finally got myslef a Europlus.

After replacing D1 to sort out the image shimmer and all the 4116's I finally got a screen up and was in basic.

Testing GR and HG I was getting parrael white lines instead of colour.

 

Now this is where I did a stupid moment. I pulled the LS02 from the far right of row B, but in a moment of blindness inserted it upside down.

 

Now what I get is a repeated ??HH pattern across the screen with odd random characters. I've no longer got a beep on start up (I was at least getting that with the original faulty RAM).

 

I've ordered some new ls02s to.replace all three in that area but wondering if anyone can suggest advice before I create a ball of smoke :)

 

 

Offline
Last seen: 3 days 16 hours ago
Joined: Mar 1 2019 - 04:38
Posts: 20
I would expect you have only

I would expect you have only damaged the LS02. With Vcc on the ground pin and 0 on the Vcc pin, I would not expect it to short out the 5v rail, rather just fail the ls02.

All other pins should have only seen normal logic levels.

 

But with an apple II a cheap 74LSxxx tester from ebay or amaxon makes life easier.

Log in or register to post comments