Controlling or observing a 7200/90 host that has a faulty logic board results in a gray screen.

Problem:

When attempting to control or observe a 7200/90 that has a faulty logic board, the screen-sharing window on the guest machine will be gray. The complete 7200/90 screen may never redraw on the guest machine. The problem is more likely to appear when the Timbuktu connection is being done over TCP/IP, and will only occur if the 7200/90 is connected to the network via its built-in Ethernet connection.

Situation:

Some 7200/90s have problems sending large packets over their built-in Ethernet connection. This can result in slow network performance that will hinder Timbuktu screen-sharing performance.

The following information was taken from Apple's Technical Information Library:
ArticleID: 18944, Title: "Power Macintosh 7200/90: Ethernet Issue"

Under certain network conditions, independent of the network protocol being utilized, the Power Mac 7200/90 may fail to successfully send large packets over Ethernet. The 7200/90 may lock-up, timeout, or cause extremely slow Ethernet performance. The problem has been isolated to the 7200/90 system's logic board and is limited to 7200/90 computers with a serial number of "xx543xxxxxx" or below.

Solution:

Follow the troubleshooting procedures contained in the aforementioned article to determine if your 7200/90 has a faulty logic board. To locate this article, go to the Search Page in Apple's Technical Information Library.

Select "Article Number" from the "Search for" drop down menu. Then type the article number: 18944. This will bring you to a link for "Power Macintosh 7200/90: Ethernet Issue"