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Author Topic: I/O board with DELIBERATELY cut tracks!!!  (Read 2035 times)

Exteban

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I/O board with DELIBERATELY cut tracks!!!
« on: January 18, 2024, 01:49:46 pm »


Hello.  I have bought an Apple Lisa 2/10, which does not turn on the CRT, and with an external display it indicates error 57 (disk Drive).  On the I/O board I have seen that it has two tracks deliberately cut.  It is normal?  Should I fix them?
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sigma7

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Re: I/O board with DELIBERATELY cut tracks!!!
« Reply #1 on: January 18, 2024, 02:27:02 pm »

On the I/O board I have seen that it has two tracks deliberately cut.  It is normal?  Should I fix them?

1) The board shown is a Lisa 2/5 I/O Board, not a 2/10 I/O Board.

It will work in a 2/10 regardless, but you should check that your motherboard matches the chassis harness as these are not interchangeable between the 2/5 and 2/10.

A 2/10 Motherboard does not have a back panel parallel port (it has only two DB-25s for serial ports). A 2/10 chassis harness has one 26 pin and one 20 pin ribbon cable in the drive cage.

A 2/5 Motherboard has a back panel parallel port (making three DB-25s, including the two for serial ports). A 2/5 chassis harness has two 26 pin ribbon cables in the drive cage, and if it has a 3.5" floppy drive, a "Lite Adapter" board connecting the drive to one of the cables.

2) The cut under C34 was done at the factory by Apple; it is normal, so you should not bridge the cut.

3) The cut under C33 is the style of an Apple modification, but Apple did not add large capacitors to the rear of any boards AFAIK, so there is something odd about that, can you provide a picture of the entire topside of the board?

4) There are likely to be wires 'tacked' on the component side; Apple made some modifications in that manner too.

5) Aside from repairs, some boards may exist that have non-Apple modifications -- if there are any, they are rare. An exception is that there are numerous 512K memory boards that have been user upgraded to be 2MB boards.

edit - added memory board exception
« Last Edit: January 18, 2024, 11:30:35 pm by sigma7 »
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Exteban

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Re: I/O board with DELIBERATELY cut tracks!!!
« Reply #2 on: January 18, 2024, 04:03:19 pm »

Oooh, thank you very much.  It is very useful information.  According to what you have told me, the motherboard is 2/5.  I have to disconnect the hard drive.  If I leave it connected, it doesn't even turn on.  I suppose the display will not turn on because the video card has some fault...

Do you know any procedure to repair it, or do I directly change the capacitors?
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sigma7

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Re: I/O board with DELIBERATELY cut tracks!!!
« Reply #3 on: January 18, 2024, 04:47:22 pm »

I suppose the display will not turn on because the video card has some fault...

Do you know any procedure to repair it, or do I directly change the capacitors?

Generally, Lisa board problems can be diagnosed to individual components, but it depends on the equipment and time you have available.

I recommend you make a separate thread/topic regarding the display problem; let us know if the filament glows in the tube and examine the video board for obvious problems such as scorched areas or burned parts. Before removing the top cover, you make sure you are aware of the potentially fatal hazards of imploding vacuum tubes and high voltages and take suitable care.

Since there is some confusion about the combination of parts in your Lisa, you may find connectors unplugged etc. from whomever was working on it. What kind of hard drive is in the drive cage?
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