Atari Portfolio Troubleshooting Guide

Atari Portfolio with a 32 KB Atari memory card

Fault-finding for the Atari Portfolio, from the supply up. The supply lines, power modes and display description come from Atari's Portfolio Technical Reference Guide. Routine care is on Atari Portfolio General Maintenance and the board's capacitors on Atari Portfolio Capacitor Replacement Guide.

How the Portfolio is powered

A switching regulator steps the voltage of three AA cells up to 5 V, and the regulator can be switched off. When cells and an external supply are both connected, the machine runs from whichever is at the higher voltage, which Atari calls the "initial source". Atari defines four power modes: NO POWER (no source connected, as during a cell change, with the system RAM held up by an internal capacitor), OFF (the custom chip and RAM run directly from the initial source), STANDBY (everything on the 5 V regulator with the processor clock stopped while waiting for a key) and RUN.

Supply lines (all are on the expansion connector)

Line	Expected	Notes
Cells	4.5 V nominal, three AA cells in series	Below the logic rail; the regulator steps it up
5VS	5 V in STANDBY and RUN; floats low at any other time	Can supply up to 40 mA at 5 V ±5% to a peripheral
VCC	Follows 5VS	Memory-card supply, separate so that inserting or removing a card does not put spikes on 5VS
VRAM	4.5 V in STANDBY and RUN; initial source minus 0.5 V in OFF; the voltage across a capacitor, decaying, in NO POWER	System RAM supply. Take no current from it in NO POWER mode or the RAM can be corrupted
VEXT	The external supply voltage, straight from the jack socket	The adaptor is 6 V DC, 300 mA, centre positive
BATD	Normally carries the initial source; pulled to ground when the cells are removed	Isolates the system RAM from the rest of the circuit

Source for the table, except where marked: Atari, section 2.5. Atari's guide gives no LCD bias voltage.

Power faults

The machine will not start

Symptom	Likely cause	Action
Nothing at all	Flat cells, or corroded contacts	Fit fresh alkaline cells. Clean the contacts and look for corrosion on the small power board and its white ribbon cable
Nothing on the adaptor, works on cells	Faulty adaptor or jack	Measure the adaptor's output and check that it is centre positive. Then check the jack on the power board
Nothing on cells, works on the adaptor	Cell contacts, power-board wiring or the step-up regulator	Check the cells under load and the contacts before suspecting the regulator
Dead after the case has been opened	Display ribbon or keyboard ribbon not seated in its connector	Reopen and reseat both. The display ribbon locks into a brown connector with a sliding part

With the machine switched on, 5VS should be at 5 V. If it is and the screen is blank, look at the display and its ribbon before the supply.

Best Electronics sells a set of three dummy AA cells, one with leads (CB102638), which it says was designed for Atari's service centres to run a Portfolio from an external 4.5 V DC supply through the battery compartment for burn-in and current tests. A bench supply set to 4.5 V with a current limit, wired the same way, shows whether a dead machine draws current at all.

Low battery behaviour

The Portfolio checks the cells during disk access, tone generation, the timer tick and every press of the Return key. If they are low it shows a low battery message and powers down, and it shows the same message at the next power-up to say why it shut down. Software can stop that power-down through Int 61h function 26h; Atari says this must only be used if absolutely necessary, because it may run the machine outside its electrical specification and damage it.

With rechargeable cells the voltage falls so steeply at the end of discharge that the warning may not appear in time.

Display faults

Blank or unreadable display

Symptom	Likely cause	Action
Blank, key clicks audible	Contrast set too light	Contrast is a software setting held in a control register. Adjust it from the keyboard first. Most machines also have a contrast trimmer on the LCD board, reached through a hole at the left of the inner bezel once the window is off
Blank, no key clicks	Power	See the power section above
Missing horizontal rows, or bands	Poor connection between the LCD glass and its driver board, or a cracked display ribbon	See below

Missing rows

Lewin Edwards described missing LCD lines as one of the most annoying Portfolio faults to fix, caused by a bad connection between the LCD and its driver board. His method, as quoted on Applefritter:

1. Prise the window (faceplate) off the display half to reveal two screws, and remove them. Best Electronics recommends warming the window with a hair dryer first.
2. Ease the display case apart. It is held by plastic clips.
3. Unscrew the LCD controller board.
4. Bend open the metal retaining tabs that hold the LCD to the driver board and separate them.
5. Clean and reseat the connection, then close the tabs.

The tabs work-harden: they survive being bent only a couple of times before they break off.

The flat ribbon between the main board and the display half, which also carries the speaker, can crack. One repairer found it cracked on a machine that had also suffered battery leakage and fitted the display from a donor machine instead of bridging the broken tracks.

Memory and storage faults

Drive C: loses its contents

While the cells are out the internal RAM is held up by a capacitor, and the voltage on VRAM decays. Atari gives neither a hold time nor a value for the capacitor.

• Contents that survive a quick cell change but not a long one are normal.
• Contents lost at once on a cell change point at the hold-up circuit. Measure VRAM with the cells fitted (4.5 V in STANDBY and RUN) before replacing anything.
• A crash also loses everything on C:. The 1992 FAQ suggests setting C: to about 8 KB with FDISK and keeping files on memory cards, which leaves about 100 KB for applications.

Memory Expander not recognised

The 256 KB Memory Expander plugs onto the 60-pin expansion connector, has a pass-through connector for a second expander or an interface, and adds a card drive B:. Installing or removing one needs a cold boot, which erases the Portfolio's memory, so back everything up first. Check that it is fully seated and clean the contacts on both connectors.

Memory card faults

Memory card problems

Symptom	Likely cause	Action
Card not readable	Card not fully home, dirty contacts, or a flat cell in the card	Reseat the card; clean its contacts with isopropyl alcohol; replace the card's cell
Contents lost whenever the card is removed	Flat cell in the card	Each Atari RAM card has its own lithium cell, which Atari says keeps the data "for a year or more" out of the machine. The cell is a CR2016
Card from another palmtop not recognised	Not compatible	Atari warns that similar cards from other makers may damage both the card and the Portfolio; the FAQ names HP, Poqet and Sharp PC-3000 cards

To change a card cell without losing data, insert the card, switch the Portfolio on so that it powers the card through the slot, change the cell, and press a key every so often so that the machine does not power down part-way through. Atari puts the keyboard time-out at 128 to 256 seconds.

Interface faults

Smart Parallel Interface (HPC-101)

• File transfer to a PC uses the FT program supplied with the interface and a male-to-male DB25 cable with all lines straight through; Atari's cable is the HPC-406. A printer needs a DB25 to Centronics cable instead.
• The transfer protocol times out after 500 ms with no answer. On a failure each end waits 500 ms, so that the other end times out too, and retries the block. Every block carries a checksum.
• The interfaces draw about as much power as the Portfolio. Run from the adaptor.

Serial Interface (HPC-102)

• The interface has a 9-pin D plug with the PC/AT pin-out, so the cable needs a female DB9 at the Portfolio end. Atari's null-modem cable for the ST and other machines is the HPC-409 (female DB9 to female DB25) and its Macintosh cable the HPC-407.
• The UART is an 82C50A with the same registers as the PC/AT, but the Portfolio has no 8259 interrupt controller. The interrupt number for the serial port is written to the Serial Interrupt Vector Register (SIVR) at I/O address 807Fh, which is write-only and must be set before the 82C50A's interrupts are enabled. Ordinary PC communication programs do not work for this reason, and the Portfolio has no terminal program built in; one has to be loaded first.
• A terminal program that waits for a key with Int 16h service 00h lets the Portfolio power down mid-session. Atari recommends polling with service 01h.

Resets

The FAQ lists three, in order of severity:

1. Ctrl+Alt+Del.
2. The reset switch in the hole on the underside above the Atari label, pressed with a straightened paper clip.
3. The cold reset: the small metal tab under the battery cover. It returns the machine to its factory state, asks for the language again and erases drive C:. It works by pulling VRAM to ground through a small resistor.

FDISK, which repartitions the internal RAM, also erases drive C:.

Things that are not faults

• The screen flashes while the machine is off. It wakes about every two minutes to check the diary alarms.
• The machine switches itself off after two to four minutes without a key press.
• A low battery message at power-up explains why it shut down last time.
• Some PC software does not run. Programs that address the hardware directly fail because the Portfolio's I/O addresses differ, it has no interrupt controller or dedicated keyboard controller, and its timer tick is different; Atari names BASIC, XTALK and Sidekick.

Diagnostic board

Atari produced an expansion-port diagnostic board with its own diagnostic ROM and 16 status LEDs. Its menus test the CPU board (system, video RAM, RAM disk, memory card, keyboard lines), the LCD board (checkerboard, rectangle, all pixels, all characters, contrast, speaker) and the keyboard, and an LED mode tests a machine whose screen does not work. Best Electronics, which sells the board, says it was never issued to Atari service centres.

Common failure points

• Cracked hinge covers. Best Electronics calls this the most common failure on old machines; the display then closes by itself or falls flat.
• Missing LCD rows from the glass-to-driver connection.
• A cracked display ribbon.
• Corrosion from leaked cells, on the contacts and, in one repairer's machine, on the keyboard circuit.

Related pages

• Atari Portfolio
• Atari Portfolio General Maintenance
• Atari Portfolio Capacitor Replacement Guide
• Atari Portfolio Technical Reference Guide
• Recommended Tools