Atari 130XE Troubleshooting Guide
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This is the component-level troubleshooting guide for the Atari 130XE and the reference for the Atari XE line. The 800XE and XE Game System guides cover what differs on those machines and refer back here.
Chip positions, part numbers, the production test and its error codes are from Atari's parts list, test instructions and schematic for the 130XE.[1] Pin assignments and the self test are from Atari's 1200XL field service manual, which documents the same custom chips,[2] and from a 2016 reproduction of Atari's 130XE field service manual, which adds FREDDIE and the XE boards.[3] Sams' service data for the 130XE is used as a cross-check.[4]
The symptom checklist in section 4 of the manual reproduction is Atari's 1200XL checklist with a few edits, and its designators (U1–U9, U12–U14, U19, U20, U23, U24, U27, VR1, SW1, CR8, the LED board) belong to the 1200XL board, not the 130XE.[3][2] Use the symptom guide below instead.
Preliminary checks
[edit | edit source]- Disconnect all peripherals: cartridge, SIO devices and controllers.
- Open the case (four screws underneath) and look around the power socket, the power switch and the board edge connectors for cracked joints, corrosion and leaked electrolyte.
- Confirm the supply before anything else. The 130XE takes +5 V DC from an external supply through a 7-pin DIN socket, J7: pins 1, 4 and 6 are +5 V, pins 3, 5 and 7 ground, pin 2 the shield.[1] There is no rectifier or regulator on the board.
- Check the power switch S1.
Supply checks
[edit | edit source]Sams' sequence for a dead machine, which protects a replacement power pack:[4]
- With the pack unplugged from the computer, measure between pins 3 and 1 of its plug. Expect 5.0 V. If it is missing, check the plug and cable before the pack.
- If the pack is dead, check for a short between pins 3 and 1 of J7 with S1 on. If there is a short, do not fit a new power pack until it is repaired.
- With a good pack connected and the machine on, measure 5.0 V at the positive end of C2. If it is missing, check S1.
The manual reproduction gives the supply as 5 V ±5 % at up to 1.5 A, so 4.75–5.25 V.[3] On the board the switched +5 V is split into three rails, +5A, +5B and +5C, each through a ferrite bead (L1, L2, L3).[1] The supply's own circuit is on Atari 130XE Capacitor Replacement Guide#Inside the power brick. Mains is present inside it and its filter capacitor holds a charge; unplug it and discharge the capacitor before opening it.
Chip map
[edit | edit source]The designators are Atari's, and Sams uses the same ones.[1][4]
| Position | Device | Atari part number |
|---|---|---|
| U1 | LM358 dual op-amp (audio) | C061702 |
| U2 | 74LS138 decoder | C061428 (alternate C014344) |
| U3 | MMU (memory management unit) | C061618 |
| U4 | BASIC ROM, 8K × 8, Rev. C | C024947A |
| U5 | Operating system ROM, 16K × 8 | C061599 |
| U6 | FREDDIE | C061922 (alternate C061991) |
| U7 | ANTIC | C021697 |
| U8 | 6502C (SALLY) | C014806 |
| U9–U16, U26–U33 | DRAM, 64K × 1, 150/200 ns | C060612 |
| U17 | GTIA | C014805 |
| U18 | 74LS08 | C017097 |
| U19 | 555 timer | C019748 |
| U20 | CD4050B buffer (video) | C010816 |
| U22 | POKEY | C012294 |
| U23 | 6520A PIA | C014795 |
| U24, U25 | CD4051B multiplexers (keyboard) | C014336 |
| U34 | Custom gate array (extended memory decode) | C025953 |
On the cost-reduced CA200519 board the sixteen 4164s are replaced by four 4464s, drawn in the reproduction at U9, U10, U11 and a fourth position labelled U2; U8 remains the 6502C.[3] A later operating system ROM, C300717, is also found.[3]
Supply pins
[edit | edit source]These are the manufacturers' pin assignments.[2][3]
| Device | Package | VCC | Ground |
|---|---|---|---|
| 6502C (SALLY), U8 | 40-pin DIP | 8 | 1 and 21 |
| ANTIC, U7 | 40-pin DIP | 21 | 1 |
| GTIA, U17 | 40-pin DIP | 27 | 3 |
| POKEY, U22 | 40-pin DIP | 17 | 1 |
| PIA, U23 | 40-pin DIP | 20 | 1 |
| FREDDIE, U6 | 40-pin DIP | 40 | 20 |
| MMU, U3 | 20-pin DIP | 20 | 10 |
| 4164 DRAM | 16-pin DIP | 8 | 16 |
| 4464 DRAM | 18-pin DIP | 9 | 18 |
Clock and reset
[edit | edit source]Sams calls FREDDIE the RAM address multiplexer.[4] The master crystal Y1 is 14.31818 MHz on NTSC machines (C070032) or 14.187576 MHz on PAL machines (C070034); some boards use an oscillator module (C070024) instead.[1] FREDDIE generates the CPU clock from it.[3] The CPU runs at 1.7897725 MHz on NTSC machines and 1.7734470 MHz on PAL machines.[5]
| Signal | Where | Notes |
|---|---|---|
| Master clock | FREDDIE (U6) pin 2 | 14.31818 MHz on an NTSC machine; if missing or off frequency, check the oscillator Y1[4] |
| Colour clock | FREDDIE (U6) pin 37 | 3.579545 MHz (NTSC); if missing, suspect U6[4] |
| CPU clock from FREDDIE | U6 pin 5 | 1.78977 MHz (NTSC); if missing, suspect U6[4] |
| Ø2 at GTIA | U17 pin 30 | 1.78977 MHz (NTSC)[4] |
| ANTIC Ø0 out | U7 pin 34 | Pin 35 is the fast Ø0 clock and pin 29 is Ø2[2] |
| CPU Ø0 in | U8 pin 37 | From ANTIC[2] |
| CPU Ø2 out | U8 pin 39 | The easiest point to scope[2] |
| RESET | U8 pin 40 | Low while reset is active; the CPU does not run until it goes high[2] |
| HALT | U8 pin 35 | The SALLY's HALT input, which ANTIC uses for display DMA[2] |
| NMI | U8 pin 6 | From ANTIC pin 7[2] |
| IRQ | U8 pin 4 | From POKEY pin 29[2] |
Self test
[edit | edit source]The built-in self test covers RAM, ROM and ANTIC; ANTIC, GTIA and POKEY; and POKEY and the keyboard.[3]
- With no cartridge fitted and no powered disk drive, hold OPTION while switching on, or type BYE at the BASIC prompt.[4] The reproduction's "press HELP at the power-on logo" is copied from the 1200XL procedure; the XE has no logo screen.
- The menu offers MEMORY, AUDIO VISUAL, KEYBOARD and ALL TESTS. SELECT moves the bar and START runs the test.
- Exit with SYSTEM RESET; HELP returns to the menu.
Holding OPTION at power-on disconnects the built-in BASIC; with no powered disk drive the machine then starts the self test.[5]
In the memory test, two long bars at the top represent the two 8K halves of the ROM, and three rows of sixteen blocks below represent the RAM, one block per kilobyte. A segment under test is white, turns light green if it passes and red if it fails, and a failed segment is not retested. A machine with the C300717 operating system ROM shows four more bars, one for each 16 KB extended bank; one with the older ROM does not.[3] The self test does not go into attract mode, so do not leave a test screen on a CRT for long.[3]
Production test cartridge and error codes
[edit | edit source]Atari's XE/XL production test cartridge, used with loop-back plugs in the SIO and controller ports, runs the production tests, audio, video, ports, keyboard, ROM and RAM tests, and on a 130XE a PBI test with a cartridge and expansion slot fixture. It reports numbered errors:[1]
| Code | Meaning |
|---|---|
| 01 | Failure in ANTIC vertical or horizontal synchronisation |
| 02 | Failure in ANTIC vertical blank interrupt |
| 03 | Failure in ANTIC display list interrupt |
| 04 | Failure writing or reading page 0 or 1 RAM |
| 05 | Failure during data line check; possible RAM failure |
| 06 | Failure during address line check (address decoding error) |
| 07 | Failure during RAM refresh check using pattern 00 |
| 08 | Failure during RAM refresh check using pattern FF |
| 10 | Failure during write to error storage (RAM) |
| 11 | POKEY timer failed |
| 12 | POKEY interrupt failed |
| 34 | Serial communication error: serial data or clock line bad, POKEY bad, or the serial loop-back plug loose |
| 35 | Serial control error: motor control, proceed, interrupt or command line bad, POKEY bad, or the loop-back plug loose |
| 36 | Serial control interrupt error: as 35, or, if 35 does not occur, POKEY, the interrupt line to the 6502, or the 6502 |
| 37 | Player port direction error: lines from the PIA to the connectors, the PIA, or the loop-back plug |
| 38 | Pot line error: player port pot lines, POKEY, or the loop-back plug |
| 39 | Trigger line error: player port trigger line, GTIA, or the loop-back plug |
| 71 | RD4 or S4 missing at the cartridge connector, or A13 missing at the expansion connector |
| 72 | MPD missing at the expansion connector |
| 73 | EXSEL missing at the expansion connector |
If errors 72 and 73 and "no sound" on the PBI test occur together, the CCTL line at the cartridge connector is missing.[1]
In the audio test the six tones come from POKEY and the following "buzz" from GTIA. In the video test, missing or overlapping players, missiles or playfields, flecks of wrong colour at their edges, or gaps in the luminance or colour bands indicate a bad GTIA; Atari notes that colours not aligning exactly across the screen is acceptable.[1]
On a RAM failure the test halts and shows the test number (1–4), the failing address, the data read, the data expected, and the bit numbers 1–8, one for each RAM chip, in red for a bad bit and green for a good one.[1]
RAM and extended memory
[edit | edit source]The 130XE has 128 KB: a main 64 KB and a second 64 KB reached through a 16 KB window at $4000–$7FFF (16384–32767), bank-switched through port B of the PIA at $D301 (54017).[4][3]
Sams gives the values for testing it from BASIC: the normal value at 54017 is 253, and POKE 54017 with 225, 229, 233 or 237 selects the first, second, third or fourth extended bank.[4] Sams' test program:[4]
10 PRINT "TESTING RAM" 20 POKE 54017, 225 30 GOSUB 120 40 POKE 54017, 229 50 GOSUB 120 60 POKE 54017, 233 70 GOSUB 120 80 POKE 54017, 237 90 GOSUB 120 100 PRINT "RAM CHECKS GOOD" 110 END 120 FOR X = 16384 TO 32767 130 POKE X,0 140 IF PEEK(X)=0 THEN 160 150 GOTO 210 160 POKE X,255 170 IF PEEK(X) = 255 THEN 190 180 GOTO 210 190 NEXT X 200 RETURN 210 PRINT "RAM BAD AT LOCATION"; X
The program selects each bank in turn and writes and reads the window, so a failure shows which bank was selected and where in the window it failed.
Connectors
[edit | edit source]| Pin | Signal | Pin | Signal |
|---|---|---|---|
| 1 | Clock in | 8 | Motor control |
| 2 | Clock out | 9 | Proceed |
| 3 | Data into CPU | 10 | +5 V / ready |
| 4 | Ground | 11 | Audio in (175 mV) |
| 5 | Data out | 12 | Not connected |
| 6 | Ground | 13 | Interrupt |
| 7 | Command |
On Atari's schematic pin 10 is fed from the +5A rail through ferrite bead L10, and the motor control line on pin 8 is switched by transistor Q7 (MPSA55) from the PIA.[1][3][5]
| Pin | Signal | Pin | Signal |
|---|---|---|---|
| 1 | Joystick forward | 6 | Trigger |
| 2 | Joystick back | 7 | +5 V |
| 3 | Joystick left | 8 | Ground |
| 4 | Joystick right | 9 | Pot A |
| 5 | Pot B |
Sams maps the controller signals onto chip pins: port 1 up, down, left and right at PIA (U23) pins 2, 3, 4 and 5, port 2 at U23 pins 6, 7, 8 and 9, and the triggers at GTIA (U17) pins 8 (port 1) and 9 (port 2). The level at those pins should go from high to low as the control is operated.[4]
| Pin | Signal |
|---|---|
| 1 | Luminance |
| 2 | Ground |
| 3 | Audio output |
| 4 | Composite video |
| 5 | Chrominance |
The cartridge slot is a 30-pin edge connector and the expansion connector beside it a 14-pin edge connector; +5 V is on cartridge pin 13 and expansion pin 7.[3]
Symptom guide
[edit | edit source]These are Sams' numbered service checks.[4]
| Symptom | Check |
|---|---|
| Completely dead | Power pack, plug, cable, J7 and S1, and test for a short at J7 before fitting a new pack |
| Powers up but does not come up properly | CPU U8, GTIA U17, POKEY U22, ANTIC U7 and the RAM at U9–U16 |
| No video | If using RF, the channel switch S2; then ANTIC U7 and GTIA U17 |
| No colour or wrong colour | The colour control R38 first; then ANTIC U7 and GTIA U17 |
| No vertical or horizontal sync | GTIA U17 |
| No key click | GTIA U17 |
| Keyboard dead | GTIA U17 and POKEY U22 |
| One key erratic | Clean the key |
| A group of keys dead | POKEY U22 |
| START, SELECT, OPTION, SHIFT, CONTROL or BREAK dead | GTIA U17 |
| Wrong characters on screen when a key is pressed | ANTIC U7, GTIA U17 and POKEY U22 |
| Cassette motor does not start | PIA U23 |
| Cassette save or load fails | POKEY U22 |
| Joystick button dead | GTIA U17 |
| Joystick directions dead | PIA U23 |
| Paddle button dead | PIA U23 |
| Paddle control dead | POKEY U22 |
Signal checks
[edit | edit source]Sams' troubleshooting section gives these checks for the 130XE:[4]
- No video with the RF output: look for video at pin 2 of the RF modulator, then at the emitter and base of the video amplifier Q3, then at pin 5 of the buffer U20. If it is present at U20 pin 5 but not beyond, check R49 and U20; if it is missing there, check GTIA U17 and ANTIC U7.
- Colour: first adjust R38. If that has no effect, check that the voltage at GTIA pin 17 changes as R38 is turned (if not, check R38 and the colour amplifier Q1), then check for 3.579545 MHz at GTIA pin 28. With no colour at all, look for the colour waveform at GTIA pin 21, then at pin 3 of the RF modulator (R203 and L32 are between them).
- No vertical or horizontal sync: check the waveform at GTIA pin 25; if it is present, check the buffer U20, diode CR4 and R51.
- No sound: run
10 SOUND 0,100,10,15:GOTO 10in BASIC and look for pulses at POKEY pin 37, then at pin 1 of the audio amplifier U1, then at the RF modulator. - No key click, but sound works: look for pulses at GTIA pin 15 while pressing a key; if they are there, check C23 and R5.
- Sound on RF but not on the monitor socket J2: check the J2 connections and R8 and R10.
- No sound from the expansion connector's audio input (J4B pin 5): check the electrolytic C22. No sound from the SIO audio input (J1 pin 11): check the electrolytic C19.
- Keyboard dead: check connector J8 and the ribbon cable, then the waveforms at POKEY pins 18–23, then at pin 3 of the keyboard multiplexer U24 while pressing a key; if that is missing, check U24 and U25.
- START, SELECT or OPTION dead: the logic level at GTIA pins 12, 13 and 14 should go low when the keys are pressed; if not, check J8, the cable and R134–R136.
- SHIFT, CONTROL or BREAK dead: look for a waveform at POKEY pin 16 while pressing them.
Things that are not faults
[edit | edit source]- No BASIC with OPTION held at power-on: OPTION disconnects the built-in BASIC.[5]
- The self test screen never blanking: attract mode is off during the self test.[3]
- Colours not aligning exactly across the production test's video screen: Atari states this is acceptable.[1]
- No extended-memory bars in the memory test: only the C300717 operating system ROM displays them.[3]
Adjustments
[edit | edit source]The only adjustment on the board is the colour control R38, a 500 kΩ preset (Atari C023030-04), reachable through a hole in the bottom of the housing.[1] Sams' method is to adjust it for a blue screen on the monitor.[4] Atari's, with the production test cartridge, is to adjust until the smaller bar inside the colour tuning bar disappears.[1]
Related pages
[edit | edit source]- Atari 130XE
- Atari 130XE General Maintenance
- Atari 130XE Capacitor Replacement Guide
- Atari 65XE Troubleshooting Guide
- Atari XE Game System Troubleshooting Guide
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 Atari (U.S.) Corp., 130XE Reference Manual (cover dated March 1990), containing the 130XE Parts List of 25 June 1985, the XE/XL Production Test Operator's Instructions and Diagnostic Error Codes, Rev. 3.4, 22 May 1986, and the Atari (Japan) schematic diagram C070065 Rev. B. Hosted on this wiki as Atari 130XE Parts List and Production Test Instructions (PDF).
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 Atari, Inc., 1200XL Home Computer Field Service Manual, FD100217, Rev. 01, February 1983, figures 1-4 to 1-8 (pin assignments of the 6502, ANTIC, GTIA, POKEY and PIA). Hosted on this wiki as Atari 1200XL Field Service Manual.
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 3.14 130XE Personal Computer Field Service Manual, reproduction by JER/Eightbitter (PDF author "Jurek"), November 2016, with schematics redrawn in May 2014. Not an Atari publication. Section 1 (pin assignments including FREDDIE, connector pinouts), section 2 (board variants), section 3 (self test). Hosted on this wiki as Atari 130XE Field Service Manual (PDF).
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 Howard W. Sams & Co., Sams COMPUTERFACTS CC16, Atari Model 130XE: service checks (p. IV), troubleshooting (pp. 9–10), parts list. Hosted on this wiki as Sams Computerfacts Atari 130XE (PDF). Its IC map agrees with Atari's designators, and it is the source of the bank-select POKE values, the RAM test program and the controller pin map.
- ↑ 5.0 5.1 5.2 5.3 Michael Current (ed.), Atari 8-Bit Computers: Frequently Asked Questions, last modified 29 November 2009, timing figures and section 1.16 (port pinouts). Text at faqs.org. Community reference.