Below is a table from the PCjr diags manual. Thought this might be
of interest to someone.
Ron--
 
       POST Error         Problem area         Probable Cause
-------------------------+-------------+-------------------------------+
| No beep. No image or   | Power       | System board or Power board   |
| wrong image on screen  |             |                               |
+------------------------+-------------+-------------------------------+
| One beep. No image or  | Display     | System board or 64K memory    |
| wrong image on screen  |             | and display expansion.        |
+------------------------+-------------+-------------------------------+
| Two beeps. No image or | Power       | System board or Power board   |
| wrong image on screen. |             |                               |
+------------------------+-------------+-------------------------------+
| Three beeps. No image  | Memory      | 64K memory and Display        |
|or wrong image on screen|             | Expansion                     |
+------------------------+-------------+-------------------------------+
| Advanced POST, or      | System Board| System board, Error 23XX      |
| portion of it goes into|             |                               |
| loop.                  |             |                               |
+------------------------+-------------+-------------------------------+
| No Beep. ERROR 0AXX    | Memory      | System board                  |
+------------------------+-------------+-------------------------------+
| No Beep. ERROR 0BXX    | Memory      | 64K Memory and Display        |
|                        |             | Expansion                     |
+------------------------+-------------+-------------------------------+
| No Beep. ERROR 0CXX    | Memory      | 64K Memory and Display        |
|                        |             | Expansion                     |
+------------------------+-------------+-------------------------------+
| No Beep. ERROR 1YXX    | Memory      | System Board                  |
+------------------------+-------------+-------------------------------+
| No Beep. ERROR 2000    | Keyboard    | Keyboard                      |
+------------------------+-------------+-------------------------------+
| No Beep. ERROR 21XX    | Infra-red   | Infra-red receiver            |
+------------------------+-------------+-------------------------------+
| No Beep. ERROR 2200    | Keyboard    | Keyboard                      |
+------------------------+-------------+-------------------------------+
| No beep. or Serial     | Cassette    | System Board                  |
+------------------------+-------------+-------------------------------+
| No Beep. ERROR 24XX    | Modem       | Internal Modem                |
+------------------------+-------------+-------------------------------+
| No Beep. ERROR 25XX    | Cartridge   |                               |
+------------------------+-------------+-------------------------------+
| No Beep. ERROR 26XX    | Diskette    | Diskette drive adapter        |
|                        | drive       |                               |
+------------------------+-------------+-------------------------------+
| Any ERROR message not  | Service plug| Ensure that service plug is   |
| listed in this table   |             | good and installed correctly. |
|                        |             | Repeat advanced POST. If same |
|                        |             | message, replace system board.|
+------------------------+-------------+-------------------------------+
 
