HP 41C Repair

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New book from The Calculator Store: HP41 Repair: A Beginner's Guide to Repairing your HP41 Calculator. 14.00€ paperback version, 9.99 Kindle version. Only in Amazon

We have been told that the book is not visible in some of the amazon websites worldwide. Here we offer links to all of them:

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Kindle and paperback versions available now!

The HP 41c family of calculators started being produced at the end of 1979 and lasted in its last versions until 1991. Such production time span attests its quality and advantages for the work of engineers and scientists. Many of you had a HP41c at its day, or lusted for one and you've given yourself that gift. But one day you pick it up from the drawer, or it falls to the ground, and it doesn't work anymore. What do you do?

Repair it!

We are fanatics of the HP calculators, and the HP41c occupies a warm place in our heart. We have repaired many of them, and we think that we have seen most of the problems that these machines have. We do not claim to have found the solution for every problem, but we have for most of them.

The first HP calculators were very solid and well designed. The body was independent of the circuits, and the screws that secured the circuit were not required to hold the machine together too. This resulted in more robust calculators. The HP41c, with all its technical advances, was not as well designed as the calculators that preceded it (with the exception of the Spice series, which was a true desing flop). We have identified several weaknesses that appear again and again, and we have found solutions for them. Click on each problem to go to the respective page.

Types of failures

- Corroded battery contacts

- Broken upper back case screw head supports

- Broken upper screw posts

- Broken lower screw posts

- Corroded or broken zebra contacts

- Corroded circuit paths

- Damaged screen - black spots

- Damaged screen - not all segments light on

- Dirty screen

- Damaged plastic protection

How to determine what is your problem? Beware - you may have to disassemble your calculator!

Corrosion on the contacts is very easy to spot. You can see the battery contacts corroded. It is usually the leftmost contact which gets corroded first. This is the lowest potential point ("-" contact)

Broken upper back case screw head supports: you can see both halves of the case are loose in the upper part of the calculator. This impedes power transfer from the battery to the circuit. If you take the upper rubber feet out with a small flat screwdriver, taking care of taking the adhesive sheet with it, you see the screws below. You will be able to see that they are "free" in this case. If they are not free, the the problem may be the broken upper repair posts - and you'll need to disassemble the calculator to see it.

Broken lower screw posts: the lower part of the calculator seems loose, and it may happen that it works when applying pressure to the lower part of the calculator keyboard (around keys 1, 2 and 3)

Corroded or broken zebra contacts: you can only see it if you open the calculator. Indicators of this problem may be missing digits or segments in the screen, or the calculator not working.

Corroded circuit paths: you can only see it if you open the calculator. Usually happens with battery contact corrosion - never comes alone!

Damaged screen: in all cases disassembly is required.

- black spots: seen in the screen. You can only change the screen (soldering required!)

- not all segments lit: it can be the connections to the screen, the lower zebra corroded, the lower screw posts broken, etc.

Dirty screen: you can try with pressured air through the side openings, and if it doesn't work you will have to unsolder the screen.

Damaged plastic protection: complicated! sometimes the damaged plastic protection is easy to take off the machine; you need to disassemble and unsolder the screen; if it doesn't separate easily, we have not found yet a way to repair it.

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Zebra + Lower post N.º de producto: zebra+lowerpost Set of zebra + lower post repair piece 26,00 € * Precio anterior 41,00 € En existencias (4) Comparar	Módulo conector de baterías y puertos de expansión de HP-41c/cv/cx N.º de producto: Flex-PCB Assembled Módulo ya montado en bastidor de impresión 3D para los conectores de batería y puertos de expansión de la HP-41c. Envío incluído en el precio para Unión Europea. Black Friday: 20% off 44,00 € * Precio anterior 55,00 € En existencias se puede enviar en 10 días (43) Comparar	Módulo conector de baterías y puertos de expansión de HP-41c/cv/cx Plano N.º de producto: Flex-PCB AssembledFlat Módulo ya montado en bastidor de impresión 3D para los conectores de batería y puertos de expansión de la HP-41c. Envío incluído en el precio para Unión Europea. Esta es la version plana, cuando las cúpulas de los tornillos están rotas y se liman a ras. Black Friday: 20% off 44,00 € * Precio anterior 55,00 € En existencias Comparar
Nuevo Conector zebra para la reparación del las HP41c full nut N.º de producto: Zebra PCB This piece is for repair of HP41c full nut calculator, substituting the damaged or corroded zebra connector that links the main board with the processor circuit. New design. Black Friday: 20% off 12,80 € * Precio anterior 16,00 € En existencias (9) Comparar	Nuevo Kit de reparación para conector de baterías y puertos de expansión de las HP-41c/cv/cx N.º de producto: Flex-PCB Circuito adhesivo para reparación para los conectores de batería y puertos de expansión de la HP-41c. Envío incluído en el precio. Black Friday: 25% off 19,50 € * Precio anterior 26,00 € En existencias (36) Comparar	Spacer set para reparar HP41c N.º de producto: SpacerSet Set of 8 pairs of spacers for nut-screwed full-nut HP41c calculators. Substitutes the nuts that are screwed on the lower posts to secure the circuit, 10,00 € * En existencias (2) Comparar
Tornillo inferior largo - inox N.º de producto: lowerscrew Dos tornillos largos para los postes inferiores de la calculadora HP41C 1,00 € / 2 unidad(es) * En existencias (1) Comparar	Tornillo inferior largo - par negro N.º de producto: lowerscrewblack Dos tornillos largos para los postes inferiores de la calculadora HP41C - black 4,00 € / 2 unidad(es) * En existencias Comparar	Nuevo Conjunto de tornillos para HP41 N.º de producto: Screwset Dos tornillos largos para los postes inferiores + otros dos para los postes superiores de la calculadora HP41C 3,00 € / 4 unidad(es) * En existencias (4) Comparar
4 x Pieza para reparación de parte trasera de HP41c N.º de producto: brokenback4 4 pieces for repairing HP41c back cases. This piece is for repair of HP41c back halves, specifically the support of the upper screw heads that is often damaged, and very difficult to repair in a lasting way. 50,00 € * Precio anterior 72,00 € En existencias (2) Comparar	Nuevo Kit de reparación de postes de HP41c N.º de producto: Lower Post Repair Kit Conjunto de puiezas para la reparación de los postes de abajo de la serie de calculadoras 41c, 41cv y 41cx full nut, incluyendo conextores cebra, recambio de postes y soporte para apoyar las pinzas y proteger el teclado. 40,00 € * Precio anterior 70,00 € En existencias (4) Comparar	Muelle para cargador de HP41c N.º de producto: Spring Muelle en acero inoxidable 304 para reemplazar muelles rotos o oxidados en portabaterías de HP41c 3,00 € * En existencias (11) Comparar
Pieza para reparación de parte trasera de HP41c N.º de producto: brokenback 1 Piece for repairing HP41c back cases. This piece is for repair of HP41c back halves, specifically the support of the upper screw heads that is often damaged, and very difficult to repair in a lasting way. 17,00 € * En existencias (10) Comparar	Nuevo Pieza para reparar postes inferiores N.º de producto: Lowpostrepair Pieza para reparar los agujeros para tornillos inferiores de la familia HP41c, del tipo full-nut 16,00 € * En existencias (11) Comparar	Nuevo Pieza para reparar postes superiores N.º de producto: UpperPostRepair Pieza para reparar los agujeros para tornillos superiores de la familia HP41c, para modelos tanto half-nut como full nut 16,00 € * En existencias (7) Comparar
Soporte teclado para reparaciones N.º de producto: keyboard support Pieza necesaria para la reparación de los postes inferiores de la HP41c 25,00 € * En existencias (1) Comparar	Trasera de HP41C reparada N.º de producto: HP41Cback Parte trasera de HP41C ya reparada, que se puede aplicar en cualquier calculadora cuya parte trasera tenga los soportes de tornillos rotos. 40,00 € * (1) Comparar	Reparación card reader N.º de producto: card reader repair Reparación de lector de tarjetas según diagnóstico. 60,00 € * (3) Comparar
Pestañas card reader N.º de producto: cardreader sidelocks 3D printed HP82104A card reader side-locks - set of left and right locks 25,00 € / 2 unidad(es) * En existencias (1) Comparar