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Minolta RP-502, RP-503, RP504A, RP-504M, RP-505, RP-507, RP-509 Microfilm Reader Printers

A brief technical perspective

Written by Evis Beaton –

In the early 1980’s, Minolta Camera Co. released a new line of plain paper, “micro-toning” system reader printers. These units were meant to replace the aging electrostatic liquid reader printer models introduced in the early 1970’s.

The RP-505 was released along with the RP-509 about 1982. The RP-505 was based on the Minolta EP-450Z Photo Copier.  This robust unit with a high production photo copier engine became an instant success and a long time top seller for Minolta across markets in banking, real estate title services, county recorders, medical records, schools and libraries.

The RP-505 used the latest in photo copier technology to produce the best image quality the industry had seen and a fast copy too. The photo copier process uses plain pre-cut letter size paper and feeds it from a paper cassette to a synchronizing roller. The paper stops for a second so that the mirrors that are aligning in the image path are ready to expose the photo conductive drum (PC Drum) that is rotating to synchronize and meet with the paper passing underneath it.

The PC drum for the RP-505 was made of a Cadmium Sulfide coating over an aluminum drum base, the CDS drum was charged by a HV corona wire above the drum as it rotated toward the exposure slit. The image from the mirror section shined down through the exposure slit where it exposed the rotating drum in areas where that light hit.  The drum continued to rotate to meet the developer section where a magnetic roller, coated with toner would spin while almost touching the drum. The toner on the magnetic roller would jump over to the PC drum where it would appear as a latent image on the drum if you stopped the process at that moment.

The PC drum continued to rotate so that as the paper passed underneath it, an HV corona wire under the paper path would attract the toner particles from the surface of the drum to the surface of the paper.

The paper then would be transported via suction belts to the fuser section (at this point if you stopped the print process you would see the image on the paper but could simply wipe it away), the paper would then enter the fuser section and be pressed and heated so that the toner on the paper would actually melt into the paper, exiting the machine a little warm but ready to use.

The RP-505 was a heavy machine, about 286 pounds without the film carrier! This unit was a work horse. The first PM schedule was 30,000 copies and often could go 60,000 copies without a service call. The RP-505 was made so well that it became a problem because customers wanted to refurbish them instead of buying new machines. I have personally worked on RP-505’s with more than 700,000 copies on the meter and I know of machines that have reached over one million prints! I guess Minolta forgot the “designed obsolescence” business model in that particular system!

The RP-505 offered auto exposure and printed from both negative and positive microfilm. It did take a full 3 minutes for the machine to warm up when cold but most photo copiers worked that way in those days, so customers did not mind. Once warm, the unit could fire off 12 prints per minute which was a great improvement in production over the liquid units and the copy quality was remarkable.

The RP-509 was the engineering model and could make prints as small as 8.5x11 but as large as 18x24. It was very robust as well, weighing almost 600 Lbs, but it was more problematic than its little brother. The RP-509 tended to have more copy quality, paper jamming and fuser issues than did the RP-505 but they both stood the test of time working well into the 1990’s and beyond.  Minolta eventually discontinued many of the parts for both systems otherwise they could be refurbished and still be in production today.

The Minolta RP-503 released around 1985 and offered a bi-mode imaging unit although that function only worked when purchasing the optional “Bi-Mode” kit.  The Bi Mode kit consisted of two new HV power supplies that could switch voltage polarity to the drum charge corona assembly, developer unit and the transfer corona wire. Minolta’s Bi-Mode toner was an advantage over Canon’s mono component system (in our opinion) which required the user to change a toner cartridge if they wanted to switch from printing with negative film to positive film. The RP-503 offered both manual and automatic exposures and offered fixed lenses for mainly 16mm applications since the output print was fixed at 8.5x11”.  The RP-503 offered an open spool 16/35mm motorized roll film carrier (RFC-10) that required control boards to be mounted inside the main unit and a bit of onsite drilling and massaging to make the whole thing work but it was a nice system that provided great prints and was considered a mid volume printer. The RP-503 borrowed its internals from the Minolta EP50 copier. Most of the internal printing mechanism was from the EP-50 copier including the paper feed, transport, imaging and fuser sections. The RP-503 did have a special CDS drum that outlasted many organic drums and could be cleaned with denatured alcohol to revive its sensitivity to light and charge.

The technical difficulties with the RP-503 were mainly in the paper take up, imaging and fuser sections. The paper take up and synch rollers were prone to contamination by toner from the imaging unit which was known to easily leak. There was even a toner tray underneath the imaging unit that collected toner coming off the DV unit that had to be cleaned periodically. The fuser section had the common issues with thermistor and upper fuser roller coating failure and occasionally had complete meltdowns requiring rebuilding. These sort of issues were common in those days and with that era of photo copier process technology in general. Minolta made an excellent product, perhaps the best in the industry but I am biased of course, having been factory trained on most of the Minolta micrographics product line.

The RP504A and RP504M as well as the RP502 were released about 1985. The RP502 was basically an RP503 except it did not offer bi mode printing or auto exposure. A trimmed down version and a little cheaper, the RP502 perhaps filed a market need for a low cost, simple all in one microfilm reader printer.

The RP-504A and RP-504M were basically RP502 units with a dedicated “ANSII” or “3M” type auto loading roll film carrier. The roll film carriers on these units later became the mechanicals for the RFC-15A and RFC-15M that were sold with the introduction of the RP-605Z and made available for many later models including the MS-6000 MKii. The RP504A/M was not a huge seller in Southern California but we did place a number of them in the field, especially in low volume applications where ANSII or 3M cartridges were used.  

Please feel free to contact me regarding Micrographic solutions or for technical support on these or other Micrographic Systems. Evis Beaton

Evis Beaton is the Sales and Marketing Manager for and has over 25 years of experience in the Microfilm Industry working as a field service technician, technical specialist and service manager for Minolta’s then largest microfilm dealer in the USA. Evis has an ASEET (Electronic Engineering Technology) and a Bachelor’s degree in Business Management with an emphasis on e-commerce organizations.

 © Evis Beaton All Rights Reserved 2015


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