Editing Schneider NLQ-401 Service Manual

The '''''Kundendienst Handbuch / Service Manual / Technical Manual NLQ 401 Drucker''''' is Schneider's service manual for the NLQ 401 dot-matrix printer. The 59-page scan has a German cover, an English technical manual in three lettered parts, and Schneider Rundfunkwerke's German spare-parts list. The troubleshooting part carries the code HDS 1000/5/85, and the parts list is dated 1985. The scan has a text layer.

== Contents ==
PDF page numbers, with the manual's own section page numbers in brackets.

* p. 1: cover
* pp. 3–34: (B) Printer Mechanism. General composition (1); principles of operation: print mechanism (1), carriage drive (2), paper feed and release (3), ribbon feed (7), control electronics (9); replacement of each part or assembly: covers, print head, logic PCB, transformer, noise filter, power switch, power cord, timing belt, carriage motor, line-feed motor, platen, paper-empty and home-position switches, switch panel (10–27); adjustment (28); lubrication (29–31)
* pp. 35–54: (C) Control Electronics. Configuration, CPU, CPU-related circuits, Centronics interface, switch panel, limit switch, paper-feed, carriage and print-head drive circuits, DIP switches, reset circuit, power supply unit (1–20), and the wiring scheme (21)
* pp. 55–56: (D) Troubleshooting, a table of failure modes, checks and probable fault locations
* pp. 57–59: spare-parts list (Ersatzteilliste) with Schneider order numbers, maker's part numbers, circuit references and prices

== What it gives ==
The NLQ 401 is a bidirectional impact printer with a nine-wire head, forming characters in a 9 × 9 matrix. The carriage is driven by timing belt MM310-3.2, which also drives the ribbon feed through an idle pulley shaft. Three paper-feed rollers below the platen are pressed against it by three springs, which the paper release lever lifts.

Two logic boards are described. Board B488013 uses an NEC µPD7810 with an external ROM, and board B488009 a µPD7809 with 8 KB of internal mask ROM; the manual says the two CPUs are not hardware-compatible. The electronics are a main CPU board and a switch board.

<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''Figures from the manual'''
! Item !! Value !! Section
|-
| Head-to-platen gap || 0.4 to 0.48 mm, set with the cams on both sides of the frame || (B) 4.1
|-
| Timing belt tension || 8 to 10 mm deflection under a 100 g load at the centre of the span, with the carriage at the left end || (B) 4.2
|-
| Lubrication || Shin-Etsu KF961 silicone oil (100 cs) or equivalent, and "grease B" at the listed points || (B) 5
|-
| +24 V supply || Unregulated: about 27 V at nominal input and no load, about 24 V during self-test printing || (C) 12
|-
| +5 V supply || From a three-terminal regulator, usually 5 V ±5 % || (C) 12
|-
| +8 V supply || Taken from the regulator input, about 7.5 V || (C) 12
|-
| −8 V supply || For the optional serial interface, about −9 V || (C) 12
|-
| Print head solenoids || About 33 Ω each to common pins 5 and 6 || (D)
|-
| Line-feed motor || About 160 Ω, green to common || (D)
|-
| Carriage motor || About 130 Ω, red to common || (D)
|}

The power transformer has input taps, and the power switch has a breaker: after it trips the power indicator stays on until the switch is turned off and on again. The troubleshooting table points to a fuse on the logic board for a printer that is dead at power-on; no fuse rating is given. The parts list itemises two electrolytics, C36 (3300 µF 35 V) and C37 (4700 µF 16 V), and the 5 V regulator.

== What it does not contain ==
There is no circuit diagram of the whole printer beyond the block diagrams, circuit-section drawings and wiring scheme in part (C), no full list of resistor and capacitor values, and no mains voltage or fuse rating.

== Related pages ==
* [[Schneider DMP3000 Service Manual]]
* [[Schneider DMP4000 Service Manual]]
* [[Amstrad DMP1 Printer Service Manual]]
* [[Amstrad DMP2000 / DMP3000 / DMP4000 Service Manual]]
* [[Amstrad LQ3500 Printer Service Manual]]

<pdf> File:Schneider NLQ-401 Service Manual.pdf </pdf>

Download: [[:File:Schneider NLQ-401 Service Manual.pdf|Schneider NLQ-401 Service Manual.pdf]] (26 MB)

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