24 June 2020

Contents

1. Archive Sidewinder activity light stays dark when powering on Sun-2 Shoebox
2. Sun-2 Mouse Compatibility
3. Sun-2 Shoebox becomes very hot
4. 3 MB memory board fails diagnostic test
5. Memory failure at 0xBD7F8

Problem Log

Archive Sidewinder activity light stays dark when powering on Sun-2 Shoebox

When powering on the Sun-2 Shoebox, the red activity light above the QIC tape slot fails to illuminate while the drive initializes (this is only observable if the top cover has been removed from the shoebox). The tape drive does not come online or otherwise respond to the system.

The 24 volt power supply has failed. It outputs zero volts at the drive power connector.

Replace electrolytic capacitor C14, near the DC output wiring harness. It is rated 2200 µF, 35 V.

Sun-2 Mouse Compatibility

The Sun-2 mouse is easily spotted, as it is black with beige buttons instead of all white like later Sun mice.

Sun-2 Mice

There are two distinct models, which may be identified through examination of the underside. Either model functions identically with any Sun-2 system, but each has different requirements for the optical pad.

Distinguishing Characteristics of M1 vs. M2 Mice

The older style, based on the Mouse Systems M1, requires an M1 pad. This pad has a coarse grid with blue vertical lines, and horizontal lines which are either red or nearly invisible. The newer M2 mouse can be used with either the M1 pad, or the more common type with (clearly visible) black horizontal lines, which is also used with Sun-3 mice.

Optical Mouse Pads

Pads with a fine grid (as used with Sun-4 and Sun Type 5 mice), are not compatible with any Sun-2 mouse. They can, however, be used with the M4 Solbourne mouse, which is fully compatible with and can be plugged directly into a Sun-2.

Sun-2 Shoebox becomes very hot

After running for twenty minutes or so, the Sun-2 SCSI Shoebox becomes very hot. It is nearly too hot to touch.

The exhaust fan has failed. It may be observed to run when the shoebox is first powered on, but after a minute or two it slows to a stop and the shoebox can no longer be adequately cooled.

The exhaust fan is a standard 120mm 12V DC brushless model, with a 2-position Molex Standard .062" type connector. The replacement should draw no more than 0.25A and be no thicker than 1.5".

3 MB memory board fails diagnostic test

When configured for use with a 4 MB CPU, the 501-1067 3 MB VME memory board fails self-tests with the following message.

Self Test found a problem in memory [addr]

Wrote 100001 at address 4FFFFC, but read 0.

1048568 total errors.
Damage found, memory (constant data) (address independence)

The 501-1067 3 MB VME memory board is designed to be used with a 1 MB CPU, to provide 4 MB of total system RAM. It cannot be jumpered to work in any other configuration, because the first memory bank of the 501-1067 is not populated.

In order to use this board with a non-1 MB CPU, two ECO wires must be installed, so that when the CAS lines for the 1st memory bank are decoded, they are routed instead to the 4th bank (with the configuration jumpers installed correctly, the 4th bank will never otherwise be activated). A generalized and abbreviated schematic diagram of the various Sun-2 VME Memory Boards is linked below, showing the necessary ECO work in red.

Sun-2 VME Memory board abbreviated schematic (573 KB SVG)
501-1020, 501-1046, 501-1047, 501-1067, 501-1070, 501-1071, etc.

Memory failure at 0xBD7F8

Self-test fails with the following message.

Self Test found a problem in memory [data]

Wrote AAAAAAAA at address BD7F8, but read AA2AAAAA.

64 total errors.
Damage found, memory (constant data)

U1307 on the CPU board (TMM41256P-12) has failed. Replace it.