Atari TT General Maintenance
.jpg)
The Atari TT030 is Atari's 68030 desktop of 1990–1993. It has an internal mains switching supply, a rear fan, a lithium clock cell, socketed TOS ROMs, a VMEbus slot and SCSI. Atari's field service manual gives its disassembly procedure, supply rating, parts list and factory rework notes.[1]
Safety
[edit | edit source]Warning: the power supply works from mains voltage, and its primary-side capacitors can hold a dangerous charge after the machine is unplugged. Unplug the TT, and measure across the supply's bulk capacitor before touching the primary side.
Use an anti-static wrist strap when handling the main board, RAM boards and VME cards.
Disassembly
[edit | edit source]Atari's procedure for removing the top cover:[1]
- Switch off and disconnect every cable from the sides and back, including the keyboard, mains lead and any external drive.
- Turn the computer over so that it rests on its top.
- Remove the ten screws in the square holes in the bottom cover.
- Loosen the retaining screw of the accessory cover with a slotted screwdriver.
- Holding the top cover, base and accessory cover together, turn the unit back over onto its base.
- Lift the front of the accessory cover and remove it. If a hard disk is fitted, stand it on its side on the top cover, disconnect its power and interface cables, and set the accessory cover aside.
- Lift the top cover off and stand it on its back behind the base. The floppy drive and power LED cables are still connected at this point.
- Disconnect the power, interface and LED cables from the floppy drive and set the top cover aside.
The floppy drive is held to the top cover by four screws and to its mounting plate by four more. The power supply is held by two screws. To remove the main board, take out its three screws and the power supply, remove the two screws holding any VME or serial card in the VME slot, unplug the cable from the serial port board, remove the card, and pull the cap off the reset switch plunger.[1]
Power supply
[edit | edit source]| Item | Rating |
|---|---|
| Type | Internal switching supply, 64 W |
| Input | 100–240 V AC, 2 A, 50/60 Hz |
| +5 V | 7 A |
| +12 V | 2 A |
| −5 V | 0.4 A |
| −12 V | 0.3 A |
Source: Atari service manual section 1.4.1.[1]
Atari's parts list gives the supply as a Phihong PSM 5341, part number C302074-001.[2] The manual gives the output currents but no voltage tolerances.
The supply reaches the main board on connector J100. Measure there, with the machine running, so that the reading includes the connector and cable:[3]
| Pin | Signal |
|---|---|
| 1 | Power Good |
| 2 | +5 V |
| 3 | +12 V |
| 4 | −12 V |
| 5–8 | Ground |
| 9 | −5 V |
| 10–12 | +5 V |
Fuse F61 and ferrite bead L601
[edit | edit source]Atari's assembly drawing for the 32 MHz main board includes a rework (ECO 1323) that covers fuse F61 and ferrite bead L601 with insulating tubing and then insulating tape, because they can short against the power supply's mounting foot.[4] Check that this insulation is still in place whenever the supply has been out, and replace any that has come away.
Cooling
[edit | edit source]The fan is on the rear panel, and the main board has a +12 V auxiliary fan header, J102.[1][3] Blow dust out of the fan and the vents, and check that the fan turns whenever the case is open. A noisy or seized fan should be replaced with one of the same size and voltage.
Clock battery
[edit | edit source]The real-time clock is an MC146818A.[5] With the machine switched on it runs from the main board supply; when the machine is off it runs from a 3.6 V lithium battery, which also keeps 50 bytes of configuration RAM.[1] Atari's parts list gives the battery as C301020-001, lithium, 3.6 V, 400 mAh.[2] It plugs into a four-pin connector, J400, on the main board.[6]
If the TT loses its date, time and settings at every power-up, the battery is flat. Replace it with a 3.6 V lithium cell. Inspect the board around the battery for corrosion whenever the case is open; see Battery Explosion, Capacitor or Corrosion Damage for cleaning, and Battery Refurbishment.
Configuration switches and jumpers
[edit | edit source]- Jumper W101 sets the processor clock: 1–2 for 32 MHz (the default), 2–3 for 16 MHz.[4]
- Jumpers W601, W602 and W603 set the type of ROM in the TOS sockets (27256, 27512, or one of two pinouts of 1 Mbit EPROM or mask ROM).[4]
- The eight-way configuration switch is set with every segment off for a 1 MB (720 KB formatted) floppy drive, and with segment 7 on for a 2 MB (1.44 MB formatted) drive.[4][7]
Floppy drive
[edit | edit source]Clean the heads with isopropyl alcohol on a lint-free swab and try known-good disks before suspecting the drive. See Floppy Drive Repair.
Atari's 1.44 MB upgrade kit, CA401220-001, was installed as follows:[7]
- Remove the hard disk, if fitted, and the top cover.
- Replace the floppy disk controller at U409 with the AJAX controller, C302096-001.
- If the TOS ROMs are older than revision 3.06, fit TOS 3.06 ROMs, CA400836-001.
- Turn segment 7 of switch J203 on the main board on.
- Set the jumpers on the back of the new drive to 1–2, 5–13 and 14–15.
- Fit the 2 MB drive, C301371-101, in bracket C302401-001, with the bracket offset away from the drive.
- Connect the interface cable to J2 and the power cable to J1 of the drive, and route the cables as Atari's figure 3 shows, behind the mounting post.
Hard disk
[edit | edit source]The SCSI port uses an NCR 5380 on a single-ended bus. The internal cable is a 50-pin ribbon, and the factory hard disk is set to SCSI ID 0.[1] Give every device on the bus its own ID and terminate the last device. The ACSI port on the back panel is a separate, ST-compatible interface. See Hard Drive Maintenance and Repair.
Audio
[edit | edit source]The YM2149 sound chip and the DMA sound system are mixed in an LMC1992 volume and tone control chip, which feeds both the internal speaker and the two RCA jacks on the back panel.[1] Sound from the speaker but not from the RCA jacks, or the reverse, therefore points at the output path after the LMC1992.
Cleaning
[edit | edit source]- Clean the case with a soft cloth and mild detergent, and clear the vents with compressed air.
- Clean the main board with isopropyl alcohol and a soft anti-static brush.
- Reseat the socketed parts: the four TOS ROMs, the coprocessor and the RAM daughterboards.
- Clean the VMEbus connector and the edge connectors of any VME card. The slot takes one single-height Eurocard.[5]
Related pages
[edit | edit source]- Atari TT030
- Atari TT Troubleshooting Guide
- Atari TT Capacitor Replacement Guide
- Atari TT030 Computer Field Service Manual
- Atari TT030 Hardware Reference Manual
- Atari TT030 Schematic
- Battery Explosion, Capacitor or Corrosion Damage
- Floppy Drive Repair
- Hard Drive Maintenance and Repair
- Recommended Tools
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Atari Corporation, Atari TT030 Computer Field Service Manual, part number C302483-001, August 1991. Section 1.4.1, power supply rating, p. 3 (PDF p. 10); section 2.2.9, real-time clock, p. 12 (PDF p. 19); section 2.3.2, audio, pp. 14–15 (PDF pp. 21–22); section 2.4.2, SCSI, p. 17 (PDF p. 24); section 4, disassembly and assembly, pp. 67–71 (PDF pp. 74–78). Hosted as Atari TT030 Computer Field Service Manual (PDF).
- ↑ 2.0 2.1 Atari Corporation, Atari TT030 Computer Field Service Manual, C302483-001, section 7, parts list. PDF p. 99: ECO 3005, 21 November 1990, changing the supply from Phihong C301379-001 to C302074-001. PDF pp. 100–101: main assembly CA400416 (4 April 1991), items 54 (C302074-001, PSU Phihong PSM 5341) and 55 (C301020-001, battery lithium 3.6 V 400 mAh).
- ↑ 3.0 3.1 Atari Corporation, TT030/32 schematic, drawing C301762-001, sheet 1: power connector J100, its decoupling capacitors, power-on LED header J103 and auxiliary fan header J102 (+12 V). Hosted as Atari TT030 Schematic (PDF).
- ↑ 4.0 4.1 4.2 4.3 Atari Microsystems Corporation, Assy. Drawing, TT030 32 MHz, drawing CA400961, 16 May 1991, in the Atari TT030 Computer Field Service Manual, section 8 (PDF p. 112): rework procedures for ECOs 1269, 1322 and 1323 (including step 10–12 and note 5 on F61 and L601); floppy-drive DIP switch settings for 1 MB and 2 MB drives; jumper W101 (32 MHz 1–2 default, 16 MHz 2–3); ROM-type jumpers W601–W603.
- ↑ 5.0 5.1 Atari Corporation, Atari TT030 Hardware Reference Manual, June 1990: feature list (PDF p. 5), real-time clock (PDF p. 12), VMEbus (PDF p. 20); the MC146818A is in its list of component data sheets (PDF p. 2). Hosted as Atari TT030 Hardware Reference Manual (PDF).
- ↑ Atari Corporation, TT030/32 schematic, drawing C301762-001, twelve sheets dated 1 July 1991, reproduced in the Atari TT030 Computer Field Service Manual, C302483-001, section 8 (PDF pp. 114–125). Sheet 1 (PDF p. 114): MC68030 U100, MC68882 U101; sheet 3 (p. 116): keyboard connector J302 and fuse F31 0.5 A; sheet 4 (p. 117): MC146818A U401 and clock battery connector J400; sheet 6 (p. 119): cartridge port J601, fuse F61 5.0 A, ferrite bead L601.
- ↑ 7.0 7.1 Atari Corporation, Atari TT030 1.44MB Floppy Disk Drive Installation Manual, part number C302563-001, 1991, pp. 1–4. Hosted as Atari TT030 1.44MB Floppy Disk Drive Installation Manual (PDF).