|Predecessor||HP 82143A and HP 82242A|
|Ports||DC barrel jack, infrared receiver|
The HP 82240 series was a line of thermal printers that support infrared communication with many HP calculators and various other devices.
|Ports||DC barrel jack, infrared receiver|
Printing to 58mm (tolerance+0/-1) thermal paper using a Seiko Industries MTP201-G166 print head with bitmap capability, these machines were also used by many instruments from manufacturers other than HP. Its influence can still be seen today where many equipment and thermal printers still use protocols derived from those first used on the HP 82240.
The printer is powered by four AA batteries and can accept alkaline or NiMH cells. External power is supplied via a common nonpolar 5.5mm/2.1mm AC jack. The manual calls for 9-12V AC or DC at 500-1500mA and thus can be used with most common barrel jack power supplies. The original power adapter HP 82241A is rated for 9V AC at 13.5VA. The printer works on either internal, external or a combination of both. It is rated for 6000 lines of print on fresh sets of internal batteries.
The printhead is of a dot-matrix type that can be directly addressed in graphics mode. When printing characters, each row is 24 (single width) characters long, with each character taking up 7x8 pixels (5 out of 7 columns are actually occupied, the outermost columns are always left blank). On each line, the leading and trailing columns are skipped. When used in graphics mode, this translates to a resolution of 166x8 per line.
On calculators that allow sending hex values directly to IR, it is possible to have a finer control of many aspects of printing. For example, double-width and single width can be toggled, underlining text can be done, and finally on the B variant, the character sets can be switched.
The IR receiver diode is mounted to the bottom left of the printer when viewed from the top, hidden behind an IR window. It is most sensitive to 940nm infrared light. Printing distance is dependent on background IR levels, with correspondingly shorter range under incandescent fixtures or in sunlight. It is usually possible to print at 15cm or more when the IR diode is in field of view indoor.
The printer was designed with a 200 bytes buffer, and as it is only set up to receive information, it is up to the controlling device to ensure long printouts does not cause an overflow. Maximum time to print a line is roughly 1.2 seconds with AC and 1.8 seconds without, accounting for the movement of print head, thus 1.8 seconds is usually set as the default DELAY value on calculators.
All variants were manufactured by the Singapore division of HP.
It is unclear when HP discontinued the HP 82240 series, but it was assumed that this was in connection with HP reorganizing its overseas divisions. The Singaporean manufacturer may have continued production under unknown name for a short period after these were discontinued.
HP 82240A[edit | edit source]
Introduced in 1986, the HP 82240A implemented a modified Roman-8 character set, which HP continued to modify moving forward from the HP 18C with which it debuted. On later calculators a translation vector was used to map internal character codes to those used by the printer, such as the OLDPRT command on the HP 48 series.
Citing a desire to reduce costs, this variant was manufactured with single sided PCB which was a departure from standard HP practice at that point. A standby mode was implemented by the chipset, however standby power drain was rather high, draining a set of fresh batteries within 2 days if the unit was left powered on, thus HP recommended always having the printer connected to an external power supply.
HP 82240B[edit | edit source]
The B revision was introduced in 1989, together with the HP48 series of calculators. Notably, this version implemented the new ECMA94 character set of the HP48 generation. To remain backwards compatible with previous printers, HP 82240 defaulted to using modified Roman-8 character set unless an escape sequence was received, which switched it into ECMA 94. The calculator can also be set to enable OLDPR which implemented a translation layer to allow printing with limited characters from A variants on the 48 and later.
Two quality of life improvement was made to the 82240: a red LED was added next to the IR receiver diode behind the window to indicate to the user that the machine is on. The machine now turns itself into standby after roughly 10 minutes of inactivity to save battery life, turning off the indicator LED, unless the mains power is connected. The user can simply press the advance paper key to wake the printer in this case.
Hardware wise, the HP 82240B switched to a green double-sided PCB with additional circuits to implement hardware standby function. The chipset standby mode was not used.
Supported devices[edit | edit source]
HP calculators[edit | edit source]
- HP 17B
- HP 17BII
- HP 17BII+
- HP 18C
- HP 19B
- HP 19BII
- HP 27S
- HP 28C
- HP 28S
- HP 38G
- HP 39g
- HP 39gs
- HP 41C, CX, CV (with IR-Interface module HP 82242A)
- HP 42S
- HP 48S
- HP 48SX
- HP 48G
- HP 48gII
- HP 48GX
- HP 48G+
- HP 49g+
- HP 50g (IrDA, but switchable to 82240 protocol, distance less than 20mm)
Non-HP calculators[edit | edit source]
Other devices[edit | edit source]
- IrDA equipped Palm OS devices (using Redeye application)
Issues[edit | edit source]
While the underlying cause is unclear, when a jam develops or when user forcefully pulls the paper, together with some key presses, the HP 82240 printhead can burn the thermal paper black or in worse case, ignite it. It is thus not recommended to have it print unsupervised.
The Seiko printhead uses two rubber rollers for paper ingest, which are glued to the main roller bar. This part can fail and run free due to age subjected to storing conditions. A tell-tale sign when this issue develops is the shrinking of line margin or persistent failure to feed. Replacing the entire printhead assembly is required in this case.
Leaving batteries in the printer for a extended period of time may lead to corrosion caused by battery leakage. Battery corrosion will most likely attack the contact tabs in the battery compartment, and is worse cases may eat away at traces on the PCB or get inside the darkness control potentiometer. The connection between the battery compartment contacts and the wires to the board are prone to failure due to corrosion. It is recommended to check this part for failure as the battery contacts also directly presses on the PCB from the underside, thus free floating power lead can cause short and circuit damage if allowed to float free.
Repair & Parts Availability[edit | edit source]
The HP 82240 is held together with 6 screws, two in the battery compartment and four under rubber feet at the bottom of the calculator. A long screwdriver bit is necessary to access these.
The printhead can be replaced with Seiko Industries MTP201-G166(E) which replaced the original printhead in Seiko listings. Five wires must be soldered. This printhead is also used for a variety of medical and scientific instruments.
The rubber pads can be easily replaced with 10mm diameter rubber feet with height of more than 1 mm.
Compatible 3rd party printers[edit | edit source]
Due to the widespread adoption of HP 82240 in various industries, other manufacturers are known to have designed compatible, or partially compatible devices. Today some of these are still in production or can be easily found second hand at much cheaper prices.
However, some of these 3rd party calculators, either does not have any HP 82240 modes other than text or uses a different hex sequence to trigger said modes. Some of these issues can be worked around with custom printing code on HP48 and later, others can't. Wherever possible, known incompatibility are noted, and the reader is advised to choose carefully according to their needs.
|No graphics mode or incompatible hex control signal|
Additionally, many printers are advertised as "HP 82240 compatible" online. In that case, always consult the instruction manual or technical documentation, or ideally request a sample / bring calculators to point of sale to test.