Apple IIc board repair UD1

[bibilit]

i am trying to repair an Apple IIc board having a video trouble.

On inspection i have a component on UD1 location (near the video connector) which looks bulged.

The marking on it is 343-1001B and looks like a resistor pack to me.

Can anybody help on identification and replacement part ?

 

[bigmessowires]

That may be normal - check out this photo: http://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Computers/Apple%20II/Apple%20IIc/Photos/Apple%20IIc%20ROM%2004%20-%20Motherboard%20Front.jpg

I agree it looks like a resistor pack, except then it should have a component name of RP-something. The fact that the component name is U-something and that it has an Apple part number makes me think it's something more complex.

 

[uniserver]

usually with the IIc, its bad ram… the ram isn't apple logo'd by chance is it?

 

[Elfen]

UD1 is a Video signal amp chip - look at the final stage of an Apple II, and all that was shrunk to that...

Video problems on the IIc is usually the RAM like Uniserver said. It can also be the Character ROM Generator.

 

[bibilit]

I have been told that can be a problem with the 14.25 Mhz Crystal oscillator ?

I have another IIc to compare with, and the the part is also bulged on one side...

 

[bigmessowires]

What are the symptoms of the video problem? Uniserver and Elfen suggested the RAM as the cause, have you investigated that?

 

[bibilit]

What are the symptoms of the video problem? Uniserver and Elfen suggested the RAM as the cause, have you investigated that?

Not yet, i am trying to get as much information as possible.

Image come and goes.

 

[bibilit]

Replace the component using one from a spare board, working fine.

 

[uniserver]

aw man that is great to hear... can you take a picture of it?  thanks!

 

[bibilit]

No problem:

the green part is the faulty one



The orange, the donor.

 

[uniserver]

the apple IIgs has a part just like that.

 

[bibilit]

Yes, spotted yesterday while working on a IIgs, which was Maxell ruined, will probably remove some parts from the board including this item, the rest is junk (casing was engraved by the previous owner, the PSU was used as spare)