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HP41c Repair

HP 41C Repair

HP 41C Repair
 
 
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
 
 
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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Nuevo Conector zebra para la reparación del las HP41c full nut

N.º de producto: zebra pair

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. Pair

12,00 *
En existencias

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

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.

55,00 *
Precio anterior 62,00 €
Todavía en existencias

Nuevo Módulo conector de baterías y puertos de expansión de las HP-41c/cv/cx (¿Montado?: Montado)

Partes para módulo de circuito impreso, o 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. Elija opción.

Nuevo precio: hemos conseguido el circuito más barato lo cual repercutimos como 10% menor precio.

59,00 *
En existencias

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

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.

14,00 *
En existencias

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

25,00 *
Todavía en existencias

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

25,00 *
En existencias

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

Nuevo Soporte zebra

N.º de producto: zebraholder

Zebra Holder to keep the elastomeric zebra connectors in the contacts between main board and processor circuit in the HP41c calculator family, full nut versions.

12,00 *
En existencias

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 *
En existencias

* Los precios incluyen el IVA

Corroded Battery contacts

Instructions for battery and ports module

 

Broken upper back case screw head supports

Instructions to repair the upper back case screw head support.

Broken upper screw posts

Upper post repair

Broken lower screw posts

Under construction

Corroded circuit paths

Under construction

Damaged screen - black spots

Under construction

Dirty screen

Under construction

Damaged plastic protection

After a lot of time, we have just found a good solution to repair your scratched HP41C screen. There is an abrasive product used to repair watches' plastic screens, called Poliwatch. You can easily get it from Amazon and other sources. 

The method: just apply a little quantity on the scratch, and then rub with a soft cloth (looong method), or use the cotton-felt tools of a dremel-type machine. This gives a bright finish in a very short time. 

Beware: do not try to use this material on crystal - it is so hard that it would not help at all.