Atari SM194
| Atari SM194 | |
|---|---|
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|
| An SM194 (atari-computermuseum.de) | |
| Manufacturer | Atari Corporation; built by Moniterm Corporation[1][2] |
| Type | 19-inch high-resolution monochrome monitor |
| Release date | Shown at CeBIT, Hannover, 8 March 1989[1] |
| Discontinued | 1991[1] |
| Interface | ECL video on a 9-pin D-sub[3] |
| Compatible | Atari Mega ST and Atari Mega STE with a graphics card; Atari TT030[1] |
| Dimensions | 368 × 452 × 381 mm (H × W × D), with tilt-swivel base[4] |
| Weight | 16.4 kg[4] |
| Successor | Atari TTM194 |
| Power | 90-137 V or 180-264 V AC, 47-63 Hz, 64 W[5] |
| Resolution | 1280 × 960[1] |
The Atari SM194 is a 19-inch monochrome monitor with a resolution of 1280 × 960, made for Atari by Moniterm Corporation of Minnetonka, Minnesota, and sold from 1989 for desktop publishing.[1] It works with the Atari TT030 and, with a graphics card, with the Atari Mega ST and Atari Mega STE.[1] Atari Benelux's technical notes identify it as Moniterm's "Viking 3" design, with VCX 1000 electronics in a plastic case.[2]
The monitor runs its picture tube at 18 kV and has a switch-mode power supply. Read CRT Discharge Procedure before opening the case.[6][7]
History
[edit | edit source]atari-computermuseum.de records that the SM194 was first shown at CeBIT in Hannover on 8 March 1989, sold from 1989 and made until 1991. It describes the monitor as designed for desktop publishing.[1] The SM194 technical manual, dated "Februari 1991", combines Moniterm's VCX documentation with notes on Atari Benelux letterhead from a Moniterm training session held on 19 April 1989. The notes record that Moniterm made three "Viking" models, the Viking 1 and 2 with VXP 1000 electronics in metal and plastic cases and the Viking 3 with VCX 1000 electronics in a plastic case, and that Atari received the VCX 1000, which had better focus, an improved power supply and a much better deflection board.[2]
On the Mega ST the monitor needs an interface card. The same notes say the card was developed by an outside developer, who wrote the driver software with Atari Corp., that the software then worked only under TOS 1.4, and that it could not switch between the SM194 and the Atari SM124.[2] The Atari TTM194 for the TT030 followed in 1990; atari-computermuseum.de describes it as technically close to the SM194.[8]
Specifications
[edit | edit source]The technical manual covers Moniterm's VCX series as a whole, which could be built for any horizontal rate from 32 to 128 kHz and vertical rate from 49 to 120 Hz. Its specific figures are for a typical monitor at 66 kHz.[9]
| Item | Value |
|---|---|
| Picture tube | 20 in diagonal in the VCX manual, 114° deflection;[9] 19 in according to atari-computermuseum.de[1] |
| Resolution | 1280 × 960; paper-white phosphor[1] |
| Scan rates | 66 kHz horizontal, 66 Hz vertical[1] |
| Video input | 1-bit ECL differential, positive is white, 75 or 100 Ω; rise and fall time 3.5 ns maximum[5][10] |
| Sync inputs | TTL, negative edge, about 100 Ω[5] |
| Display size | 14 × 11 in ± 0.1 in[10] |
| Mains | 90-137 V or 180-264 V AC, 47-63 Hz; 64 W; inrush 40 A peak at 120 V, 60 A at 220 V[5] |
| User controls | Brightness and power switch; contrast on grey-scale units[11] |
| Dimensions and weight | 368 × 452 × 381 mm (14.5 × 17.8 × 15.0 in), 16.4 kg, with the tilt-swivel cabinet[4] |
Moniterm's alignment specification for the "Viking VCX 91 DPI 220V" (part number 903-0279-03 Rev. B) gives the timing as a 62.176 MHz dot rate, 66.43 kHz horizontal and 66.43 Hz vertical, and the anode voltage as 18,000 V ± 100 V.[6]
Interface
[edit | edit source]| Pin | Signal | Pin | Signal |
|---|---|---|---|
| 1 | ECL video | 6 | ECL inverted video |
| 2 | ECL video return (ground) | 7 | ECL inverted video return (ground) |
| 3 | H sync | 8 | Sync return (ground) |
| 4 | V sync | 9 | Not connected |
| 5 | Not connected |
Mains enters through a CEE-22 receptacle.[3] The manual notes that other pin assignments could be made to order.[3]
Hardware
[edit | edit source]The monitor is built from four assemblies: a switch-mode low-voltage supply, a high-voltage supply, a deflection board and a video board.[2][7]
- Low-voltage supply: a discontinuous flyback converter controlled by a 3842 current-mode PWM IC (U1) driving Q1, synchronised to the horizontal flyback. The input works as a bridge on 220 V and as a voltage doubler on 110 V, chosen by a header. The Atari Benelux notes give the outputs as 9, 25 and 40 V, and say that connecting a set wired for 110 V to 220 V blows a fuse, after which the supply runs on 220 V.[7][2]
- High-voltage supply: a resonant regulator run from the 25 V rail, which makes the anode voltage, 1200 V and −120 V. A remote shut-down turns it off.[7]
- Deflection board: a 74LS221 one-shot (U4) and a TLC555 (U1) process the sync; an MC1391 phase-locked loop (U2) drives the FET Q3 and the horizontal output transistor Q7; a TDA1670 (U3) does the vertical deflection. If either deflection stops, Q8, Q9 and Q10 shut down the high voltage to protect the tube from burns.[12]
- Video board: on the 1-bit ECL board an MC10H125 ECL-to-TTL translator drives the cathode through Q1 and Q2, and spark gaps protect G1, G2, G4 and the cathode against arcs.[13]
Repair
[edit | edit source]The technical manual's troubleshooting chart covers a monitor that does not switch on: check the mains and the fuse; with the fuse intact, measure the 85 V line (R56) to ground on the deflection board, where a short means Q7, D10 or D23; with the fuse blown, take out the power supply and check Q1, D6 to D10, D12, Q3, D13 and D14 for shorts before testing the supply on a DC load.[14] The Atari Benelux repair notes add a table of normal resistances on each supply output:[15]
| Output | Normal resistance | If wrong, check |
|---|---|---|
| 9 V | 4.3 MΩ without the video board; "20" with it (no unit given) | The supply, D8, R220 |
| 25 V | 2 kΩ | U2, U3 and the diodes round them; the supply diodes |
| 40 V | 3-4 MΩ | Supply diode D10 |
| 100 V | 7.3 MΩ | Q7, T2 |
| 120 V | 14 MΩ | High-voltage unit, deflection protection |
| 1200 V | 8-9 MΩ | High-voltage unit, deflection protection, Q5, D5 |
The same notes say: for a supply fault check V1, the FET, the transformer and the output diodes, and if the transformer has failed replace V1 and the FET as well; potentiometer 1 sets all the DC outputs and potentiometer 2 the high voltage; if the coil housing ("spoelhuis") is faulty, check T2, Q7 and D32/37, and replace all of them when the coil housing is replaced; and if the 9 V supply has failed, possibly V5 on the deflection board.[15]
A 2001 report on the classiccmp mailing list from someone who had repaired a batch of surplus Moniterm 19-inch monitors said most needed their first-stage video amplifier transistors replaced and a general alignment. It concerns Moniterm 19-inch monitors in general, not the SM194 in particular.[16]
Documentation
[edit | edit source]- Atari SM194 Documentation: the February 1991 SM194 technical manual.
Related pages
[edit | edit source]- Atari SM194 Documentation
- Atari TTM194
- Atari SM124, Atari SM125, Atari SM146, Atari SM147
- CRT Discharge Procedure
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 "Atari SM194 High-Resolution Monochrome Monitor", in "Atari ST-Peripheriegeräte", atari-computermuseum.de, https://www.atari-computermuseum.de/st_peri.htm#sm194. Secondary source for the maker, first showing, dates, compatibility, resolution, scan rates and phosphor.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 SM194 Technical Manual, appendix, Atari Benelux notes in Dutch on the Moniterm training of 19 April 1989 and on the Viking models, PDF pp. 33 and 36.
- ↑ 3.0 3.1 3.2 3.3 SM194 Technical Manual, section 10, Interface, PDF p. 12.
- ↑ 4.0 4.1 4.2 SM194 Technical Manual, section 7, Mechanical Description of Optional Cabinet with Tilt-Swivel Base, PDF p. 11.
- ↑ 5.0 5.1 5.2 5.3 SM194 Technical Manual, section 3, Electrical Characteristics, PDF pp. 3-5.
- ↑ 6.0 6.1 SM194 Technical Manual, appendix, Moniterm Corporation, Configuration and Alignment Specification, Viking VCX 91 DPI 220V, part number 903-0279-03 Rev. B, PDF p. 32.
- ↑ 7.0 7.1 7.2 7.3 SM194 Technical Manual, section 11.2, Power Supply, PDF pp. 18-21.
- ↑ "Atari TTM194 / TTM195", in "Atari ST-Peripheriegeräte", atari-computermuseum.de, https://www.atari-computermuseum.de/st_peri.htm#ttm194. Secondary source.
- ↑ 9.0 9.1 SM194 Technical Manual, February 1991, sections 1 and 2, Scope and General Description, PDF p. 3. File:Atari SM194 Technical Manual (February 1991).pdf.
- ↑ 10.0 10.1 SM194 Technical Manual, section 4, Display Performance, PDF p. 5.
- ↑ SM194 Technical Manual, section 5, Controls, PDF p. 9.
- ↑ SM194 Technical Manual, section 11.1, Deflection Board, PDF pp. 13-18.
- ↑ SM194 Technical Manual, section 11.3, 1 Bit ECL Video, PDF p. 22.
- ↑ SM194 Technical Manual, appendix, troubleshooting chart "Monitor does not turn on, LED does not light", PDF p. 30.
- ↑ 15.0 15.1 15.2 SM194 Technical Manual, appendix, Atari Benelux "Reparatie tips" (repair tips), in Dutch, PDF p. 35.
- ↑ Reply to Douglas Quebbeman, "A2024/Viking Moniterm", classiccmp mailing list, 9 February 2001. https://www.classiccmp.org/mailman3/hyperkitty/list/[email protected]/thread/TSIHT54ZP6LGKAJF667OPL7IB5IWHB2L/. Community repair report.