Coleco Adam Troubleshooting Guide
Fault-finding on the Coleco Adam. Coleco's own ADAM System Check-Out and Trouble-Shooting Guide (code 42464E) gives a step-by-step check of the system and the printer adjustments;[1] the Technical Reference Manual and Coleco's schematics give the power supply rails, the cable pinout and the regulator circuit.[2][3] Cleaning and care are on Coleco Adam General Maintenance and capacitor values on Coleco Adam Capacitor Replacement Guide.
Before you start
[edit | edit source]- Take any data pack out of the drive before switching on or off. Coleco warns that a data pack left in the drive when the Adam is turned on or off, or a moving pack when the power is cut, can be erased.[1][4]
- Do not connect or disconnect any component, cable or the daisy wheel with the power on.[1]
- The Adam runs on 108–132 V mains. Coleco advises against sharing an outlet circuit with appliances containing motors, and recommends a line conditioner or transient suppressor where the supply is poor.[1]
- The power supply in the printer carries mains on its transformer primary and switch. Unplug the printer before opening it.[3]
Coleco's power-on check
[edit | edit source]With no data pack in the drive and no cartridge in the slot, switch on at the OFF/ON switch on the back of the printer.[1]
- The red light at the bottom right of the keyboard comes on. If only the light fails, the computer still works normally.
- The printer hums, and the print mechanism moves to the left and clicks. In full, it should move left, spin the daisy wheel, move about an inch to the right and stop.
- The TV or monitor shows the SmartWRITER electronic typewriter screen.
- If the print mechanism first moves right, or moves left and sticks or vibrates, switch off and go to Printer.[1]
If nothing comes on
[edit | edit source]| Check | Detail |
|---|---|
| Power switch | The OFF/ON switch on the back of the printer is at ON |
| Mains | The power cord is plugged in and the outlet works |
| Reset switches | The COMPUTER RESET switch, and on the complete system the CARTRIDGE RESET switch, slide freely and are not stuck in the reset (frontmost) position |
| Expansion Module #3 | The ColecoVision's own power supply is not plugged in, and its ON/OFF switch is off |
| Cables | The "computer" cable from the back of the printer goes to the left side of the memory console; the coiled keyboard cable goes to the front of the memory console |
| Printer mechanism | Roll the paper advance knob back and forth a few times to make sure the mechanism is not jammed |
All from the check-out guide, pp. 2–3.[1] If these are all correct, measure the supply rails as below.
Supply rails
[edit | edit source]The printer feeds the memory console through a cable of seven insulated wires and a drain wire. Coleco's Technical Reference Manual gives each conductor and its voltage:[2]
| Pin | Colour | Signal | Nominal | Tolerance |
|---|---|---|---|---|
| 1 | Brown | +12 V logic (+12VL) | 12 V | +0.508 V / −0.6 V |
| 2 | Red | +12 V inductive (+12VI) | 12 V | +0.497 V / −0.6 V |
| 3 | Orange | +5 V | 5.075 V | +0.079 V / −0.255 V |
| 4 | Yellow | −5 V | −5.15 V | ±0.25 V |
| 5 | Green | Ground | – | – |
| 6 | Blue | AdamNet | – | – |
| 7 | Violet | Reset | – | – |
| 8 | – | Drain | – | – |
| 9 | – | No wire | – | – |
The connector on the memory console is a DE-9. Leaded Solder used this pin order to build an external supply and confirmed the voltages at the connector; find pin 5 by checking continuity to the console's ground before measuring.[5]
Full-load currents to the memory console are 2.75 A on +5 V, 0.2 A on −5 V, 0.6 A on +12VI and 0.3 A on +12VL.[2]
Tracing a missing rail
[edit | edit source].png)
Each rail has its own transformer winding, rectifier and regulator:[3]
| Output | Winding | Rectifier and reservoir | Fuse | Regulator |
|---|---|---|---|---|
| +5 V, 3.0 A | 7.25 V AC | BR1, C2 10,000 µF 16 V | F1, 5 A slow-blow | µA723 (U1) with 2N3055 (Q1) and TIP31A (Q2) |
| +12 V inductive, 2.55 A, and +18 V unregulated | 14.0 V AC | BR2, C8 15,000 µF 25 V | F3, 5 A slow-blow | µA723 (U2) with 2N3055 (Q3) and TIP31A (Q4) |
| +12 V logic, 0.3 A | 15.0 V AC | CR17–CR20, C15 3,300 µF 25 V | None | µA723 (U3) with TIP41A (Q6) |
| −5 V, 0.2 A | 8.25 V AC | CR4, CR9, CR10 and C20 470 µF 16 V | None | 79M05 (U4) |
- Unplug the printer and check the fuse for the dead rail, F1 for +5 V or F3 for +12VI and the 18 V line.[3][2]
- If every rail is dead, suspect the mains side first: the switch, the cord, and the thermal fuse built into the transformer.[2][3]
- With the supply running, measure across the reservoir capacitor of the dead section. No DC there means the winding, bridge or fuse; DC there but nothing at the output means the pass transistor, driver or µA723.[3]
- The +5 V and +12VI outputs have foldback current limiting, so an overload in the memory console can hold a rail low with its fuse intact. Disconnect the memory console and measure the supply unloaded before condemning it.[2]
On the schematic, R9, R20, R31, R33, R34 and R35 are optional trim resistors selected at test. An empty position at one of these is not a fault.[3]
Picture and sound
[edit | edit source]- Set the TV to the same channel, 3 or 4, as the switch on the back of the memory console (or the ColecoVision with Expansion Module #3), and set the switch box to "game" or "computer".[1]
- For interference, coil the video cable about 6 in across with at least three turns and tie it, move the computer away from the TV, plug the two into different outlets, or use a shorter shielded 75 Ω cable.[1]
- On a monitor, connect the video input to the console's MONITOR socket and audio from pin 1 of the AUX VIDEO DIN socket (pin 4 ground); set the monitor to 75 Ω.[1]
- With audio from a side-port expansion such as the Super Game Module, owners report hum caused by the position of one wire from the DIN socket; John Lundy documented a fix that moves the wire, and Jeff's Coleco Adam blog describes making it.[6]
Keyboard and controllers
[edit | edit source]- Nothing happens when typing: check the POWER ON light, check that the keyboard cable is firmly in at both ends, and pull COMPUTER RESET. A telephone cable will not work in place of the keyboard cable.[1]
- On rare occasions the keyboard stops responding; Coleco's fix is to unplug the keyboard from the memory console and plug it back in with the power on.[1]
- Controller not responding: check that it is firmly in its port on the right side of the memory console (or the ColecoVision), and that player 1 uses port 1.[1]
Digital data drive
[edit | edit source]If one data pack will not load, the pack is the likely fault; if no pack loads, the drive is.[1]
- Open the door only when the tape has stopped, take the pack out, reinsert it with the label facing out and the exposed tape downwards, and try again.[1][4]
- If all the tape has wound onto the right-hand spool, wind the empty spool back a few turns by hand.[1]
- If the tape is wound unevenly, tap the label side of the pack on a hard flat surface, then the other side, until it winds evenly.[1]
- With the pack out, check that the rubber roller turns freely: spin it gently with the eraser end of a pencil, without touching the head.[1]
- Clean the head with a foam swab moistened with isopropyl alcohol.[1]
- Switch the Adam off and wait ten minutes before trying again.[1]
Coleco's guide describes removing and refitting the drive; the steps are on Coleco Adam General Maintenance.[1]
Printer
[edit | edit source]| Symptom | Check |
|---|---|
| Wrong power-on sequence, wrong printing, left margin not kept | Roll the paper advance knob back and forth to clear a jam; check the carriage return switch contacts; look for obstructions to the print mechanism; check the carriage cable is tightly wound; lubricate the rods; check the printer connectors; switch off and retry after ten minutes |
| Wrong characters printed | Use a 96-petal daisy wheel with Coleco's character order; check for obstructions; re-align by pulling COMPUTER RESET; check the wheel for broken petals and that it is firmly on its peg |
| Characters unclear or cut off | Push down on the front of the print mechanism; reseat the daisy wheel; check the ribbon is not tangled and take up its slack; check the hammer adjustment |
| Loud hum or platen not advancing | Roll the paper advance knob back and forth at once |
| Paper feed tight | Feed several sheets together to ease it; grease the inside edge of the paper advance knob |
| Vibration noise | Stand the printer on a solid surface with a thick pad under it |
Details and the adjustments themselves are on Coleco Adam General Maintenance.[1]
Things that are not faults
[edit | edit source]- The SmartWRITER resets and feeds the paper one line every time the computer is reset.[6]
- The POWER ON light on the keyboard can fail without affecting the computer.[1]
- In SmartBASIC's high-resolution modes, two different colours plotted next to each other give odd results; Coleco says this is how the graphics chip works, not a fault.[1]
Running without the printer
[edit | edit source]Because the supply is in the printer, a failed printer supply stops the whole system. Owners have built or bought external supplies that plug into the memory console's power connector instead; Leaded Solder built one on a 45 W Mean Well RQ-50B module and estimated the console's needs at about 25 W.[5][6]
Related pages
[edit | edit source]- Coleco Adam
- Coleco Adam General Maintenance
- Coleco Adam Capacitor Replacement Guide
- Coleco Adam Documentation
- Capacitor Failure Symptoms
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 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 Coleco Industries, ADAM System Check-Out and Trouble-Shooting Guide, code 42464E, 1983: operating tips (p. 1), power-on check and "if the computer does not come on" (pp. 2–3), picture checks and the interference coil (pp. 3–4), keyboard and game controller (pp. 5–6), data drives and data packs, drive removal (pp. 7–8), printer checks, carriage return switch, lubrication and print-quality adjustments (pp. 9–14), monitor connection and AV DIN pinout (p. 16), SmartBASIC and additional tips (pp. 21–23). Hosted here as File:Coleco Adam System Check-Out and Trouble-Shooting Guide 42464E.pdf.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Coleco Industries, ADAM Technical Reference Manual, Preliminary Release, chapter 2 section 6 (power supply rails, protection, the printer to memory console cable, full-load currents; PDF pp. 48–49). Hosted here as File:Coleco Adam Technical Reference Manual (Preliminary Release).pdf.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Coleco Industries, Schematic, Linear Power Supply, drawing 41234 revision E, used on 83-101, sheet 7 of File:Coleco Adam Schematics.pdf: windings, rectifiers, reservoir capacitors, fuses F1 and F3, regulators, output currents, and the note that R9, R20, R31, R33, R34 and R35 are optional resistors selected at test. Also File:Coleco Adam linear power supply schematic (41234).png.
- ↑ 4.0 4.1 Coleco Industries, ADAM Family Computer System Set-Up Manual, revised edition, by Deborah J. Miller and Deborah Q. Voosen (Coleco and Robert J. Brady Co., 1983–1984): inserting and removing data packs, care of the computer, printer and data packs (temperature range 10–52 °C), operating hints. Hosted here as File:Coleco Adam Family Computer System Set-Up Manual.pdf.
- ↑ 5.0 5.1 "I don't know you from Adam", Leaded Solder, 19 November 2022, leadedsolder.com (retrieved 2026-10-06): the DE-9 power connector pinout (pins 1 and 2 +12 V, 3 +5 V, 4 −5 V, 5 ground) taken from an AtariAge thread and checked with a meter; an external supply built on a Mean Well RQ-50B; the keyboard's 6801-family controller.
- ↑ 6.0 6.1 6.2 Jeff, "Hardware" posts, Jeff's Coleco ADAM Blog (retrieved 2026-10-06): 16 May 2021 "Soldering for Super Sound" (unbalanced audio from side expansions caused by one wire from the 7-pin DIN, fixed by moving it, following a document by John Lundy); 20 June 2020 (the printer resets and feeds a line whenever the computer is reset); 30 October 2020 and 26 February 2024 (external replacement power supplies).