IBM 5155  -  CRT Display Unit    ("IBM Portable PC Display")


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Connection to IBM CGA card

A photo showing the connection is here

IBM's technical documentation on the CRT Display Unit

1. Click on this link to get to the 'Options & Adapters' web page.
2. On that web page, click on the link named 'IBM Portable PC Display'

Removing the shield

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Chip IC101

From 'Hugo Holden' of the Vintage Computer Forums, FEB2017:

There is an IC in these monitors labelled IC101 in the IBM documents with another number 221-88 or 86. The actual IC is a Horizontal sync processor & oscillator for the H scan circuits. The IC in these monitors I have, had their original labels deliberately inked over and a sticker applied on top. Looking under that, the IC has numbers printed on it that are 221-141 and L8420 which was probably the date and not a definite commercial part number. But, after a bit of research, I have concluded that this IC is definitely the Motorola MC1391P. This information might also help others repairing these vintage monitors.