I recently recovered an old one Commodore MPS 803 dot matrix printer, abbandonata in cantina. Le sue condizioni non erano proprio ottimali, ma, per fortuna, funzionava. Ho quindi deciso di procedere ad un'accurata pulizia e lubrificazione.
Commodore MPS 803 Printer Features
The Commodore MPS 803 printer is a dot matrix printer, produced since 1985. It can print on single sheets of A4 paper, but also on continuous form paper, using an optional cart.
The characters, already present in Roma, consist of a 7x6 points matrix. The density is 10 characters per thumb. With regard to printing performance, the Commodore MPS 803 can print in a bidirectional way (both when the head advances and when it returns), with a speed of 60 characters per second.
Printing method: dot matrix printing (Impact Dot Matrix).
Character dot matrix: 7 (height) x 6 (width) dots.
Dot size: 0.3mm.
Print speed: 60 characters / second.
Character size: 2.4mm (height) x 2.2mm (width).
Text line width: 80 columns.
Printing method: bidirectional printing.
Paper transport: single pages or units (tractor) for optional continuous paper.
Type of tape: KMP tape, black nylon.
Paper width: A4, Letter and optional continuous paper from 102 mm (4 inches) to 254 mm (10 inches) wide.
Copy / carbon copy: original + 2 carbon copy.
Graphic printing: 7 vertical dots, 480 horizontal dots, per line.
CPU: NEC µPD7811G, 128 byte di RAM, 10 MHz.
ROM 4 KB (EPROM 2732).
Power Consumption: 8W idle, 30W printing.
Weight: about 2 Kg.
Internal and external cleaning of the Commodore MPS 803 printer
Per smontare la stampante e pulirla internamente ed esternamente, ho dapprima rimosso il carrello per il modulo continuo (tractor), poi il coperchio superiore, infine il nastro dell'inchiostro. Per questa operazione non sono necessari attrezzi specifici.
Ho quindi svitato le due viti che fissano il secondo coperchio. A questo punto si può rimuovere anche questo secondo coperchio, che protegge l'interno della stampante.
Pay attention to lift the cover, because the cable for the button and the LED is present, which must be disconnected from the motherboard.
After releasing and removing the cover, you can move on to removing the printing unit, which contains the roller, head and motors.
Here too, it is necessary be careful not to tear the electric cables. First you have to move the head all the way to the right. The head flex flat cable can then be pulled out of the motherboard.
After unscrewing the two fixing screws of the printing unit, disconnect the rear connection cables (those of the stepper motors and the micro switch).
The printing unit is equipped with some adjustment levers. I recommend consulting the service manual, attached at the bottom of this page, for further information.
As can be seen from the service manual, the printing unit can also be disassembled by removing the roller, gears and other components. If you are not experienced, I do not recommend disassembling the printing unit.
In the lower part of the printing unit, there is the microswitch that aligns the head to the left: I recommend deoxidizing it.
Once the printing assembly is removed, you have access to the motherboard.
Per rimuoverla, bisogna svitare le viti che la fissano, le viti dei cavi di massa, nonché allargare delicatamente i gancetti di plastica. Anche gli altri componenti possono essere rimossi, per procedere ad un'accurata pulizia della parte inferiore del case. Rimuovere la scheda madre e gli altri componenti è un'operazione è un po' delicata: I only recommend to those who have a good dexterity to do it.
After having brushed and cleaned carefully (but gently) all the parts, it is possible to proceed to lubricate the rotation parts (gears, trees, etc ...) and the guide (metal bar) that supports the print head. As I suggested before, it is advisable to read the service manual (attached at the bottom of this page) to clean, lubricate and adjust the printing unit.
Anyway, avoid using too much lubricant! The quantity must be minimal and, above all, the lubricant must be carefully positioned, without dirtying and mixing the other parts.
After having cleaned and lubricated everything, it is possible to reassemble the Commodore MPS 803 printer. To reassemble it, simply retrace the steps described above in reverse! Remember to reconnect all the cables (including the 4 of the printing unit and that of the button / LED) and to gently screw all the components back on.
As you can see, the result is excellent and the printer, reassembled, looks really good!
To test the printer, I used the Easy Script word processor. I made a video with step-by-step instructions for using Easy Script and printing with the Commodore MPS 803 printer.
Documentation
In support of this article, I attach the Commodore MPS803 printer service manual.
Ciao Amedeo, sto restaurando una MPS 803 il modello marrone, ho smontato tutto, pulito le plastiche, recappato, lubrificato la meccanica, e dal momento che l'asse dove scorre la testina era molto sporca e ruvida l'ho dovuto sfilare per pulirla per bene ma solo dopo mi sono accorto di non essermi segnato la posizione delle linguette per il distanziamento tra aghi e rullo che sul manuale viene riportato come "Clearance adjusting Level" https://www.manualslib.com/manual/1362768/Commodore-Mps-803.html?page=59#manual
Sai qualche metodo accurato per poter calibrare l'asse su entrambi i lati?? il manuale riporta di settarlo da 0,4 a 0,45mm ma come potrei fare a occhio?? il calibro non ci entra..
Thanks in advance
Ciao! Per la calibrazione si possono utilizzare degli spessori calibrati (spessimetri). Si possono acquistare senza spendere troppo. In alternativa, se hai dei fogli plastici un po' spessi, potresti misurare, con il calibro, lo spessore dei fogli, sperando di trovarne uno da 0,4-0,45 mm.
In the meantime, thank you for answering me, unfortunately I have not found a reliable measurement point with the gauge, but I will try with feeler gauges between the roller and the head ..
p.s. restauro spettacolare!! compreso di scatola, polistirolo, manuali, cavi trattore, sembra tutto nuovo!! e poi vuoi mettere il suono "esotico" di una stampante a 9 aghi degli anni 80 🙂
p.s 2 your site and your guides are spectacular !!! very cool !!!!!!!!!! and always current 🙂
Thanks so much! Indeed, the sound of the dot matrix printer is beautiful. Have you seen the video article where I connected it to a modern PC with Windows 10?
Ciao Amedeo si ho visto tutti i tuoi video, sono stati molto utili a partire dalla guida per la configurazione di opencbm a quella per poter mandare l'output di stampa su mps803, dove tra l'altro ho provato a stampare qualcosa dopo aver rimontato tutto e funziona alla perfezione come 40 anni fa 🙂
I imagine that at 12 you were someone who used 5¼ floppies and maybe exchanged them with rare friends who shared this primordial passion who also had the possibility to do so, at the time we were aliens so today it's normal but the memory is so tender 🙂
Hello! I am pleased to! 🙂 Indeed you are right, when I was in elementary school I had the Commodore 128 and a friend of mine the ZX Spectrum. Then, since I was 10, an IBM PC came into the house, which I never gave up. With that, I had 3.5 inch floppies to swap!
Hello Amedeo, could you tell me if there are spare tapes on the market and if you where you can buy them? Thank you!
Hello Joseph. The tapes are on eBay, there are foreign sellers who market them. If you pay with PayPal you are guaranteed to receive the goods.
Hey there! Do you use Twitter? I'd like to follow you.
I'm enjoying your blog and look forward to new posts.
Hello! Yes, I am on several social networks.
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