After a decade of providing hundreds of full HP-23D kits to satisfied customers, the HP-23D has stood the test of time and has become the premiere rebuilt kit for the Heathkit power supplies.  

The HP-23D is now offered only as a Printed Circuit Board and a full instruction CD with information on the needed parts.  The CD also includes a wealth of information on the HP-23 series of power supplies including schematics, pictures and comparisons of all the models sold by Heathkit. 

The PCB and the  complete instruction CD is available for just $18.  You get the PCB and the instruction CD shown below but no other parts.  The CD includes details about the part requirements and several sources for parts.  A recent survey of one source showed all the parts except the mounting hardware totaled only $23.36.  That section of the CD is also shown here by clicking on HP-23D Parts.  

Order at the KITS Page.

Because of the low price of the PCB and CD, we can not offer any assistance in ordering your parts to complete the kit.  It may require looking at other part distributors for availability and to get the lowest prices, especially for capacitors.  

The descriptions below primarily refer to the full kit and not the PCB Special.   



With the advances in component technology since the work-horse Heathkit 23-series power supplies were sold, new components are now available which are smaller in size and have higher ratings than the original components.  The HP-23D replacement board replaces all the fixed resistors, capacitors, and diodes in the Heathkit power supplies with all new and mostly higher rated components (voltage, wattage, capacitance, and/or temperature).  The result is a power supply (called the HP-23D) in which all the components which usually go bad are replaced with new components, thereby bringing your power supply back to original or better performance, maybe for another 35 years.  

The HP-23D works with any of the 23-series power supplies (HP-23, HP-23A, HP-23B, HP-23C, and PS-23). See Model Comparison Page. All the model-specific functions of your PS remain the same with the HP-23D PCB, such as ON-OFF & LV switching, adjustable bias, circuit breaker, pilot light, etc., if those features are included in your model. 

The HP-23D installs completely within the chassis for safety purposes.  The instruction CD is run on your PC and contains detailed building instructions with color pictures of each step. 

Experience Level: The kit requires some degree of building and electronic experience, and some spare time.  This is not a project for a first time kit builder or someone with limited technical knowledge. The instructions are not as detailed as in most Heathkit manuals, but should be more than sufficient. If you can read schematics, have experience soldering components to a PCB, and can identify components and determine their  polarities and values from their markings, you should have no trouble. You will need to have a PC to run the instruction CD, normal electronic construction tools and solder, some hookup wire and miscellaneous items if needed, etc. No drilling new holes in the chassis is required. An understanding of the danger of high voltages and how to work with them, and the ability to make sure your finished product is constructed in such a manner that its high voltages are not a hazard to anyone or anything, is very important. 

Basically, you build the board, remove the old capacitors, fixed resistors, and diodes from your PS (leave the transformer, choke, 11-pin connector, etc.), and connect the PCB to the remaining components in the PS at points on the PCB which are identified on the silk screen legend on the PCB.  In most cases the leads left on the PS will be long enough to reach the proper point on the PCB for soldering, but some lead extension may be needed if they were cut short during the original construction. 

Pictures of built boards*, installed in a PS, and generalized schematic are below.  Click on pictures to enlarge.

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BONUS: The step-by-step instructional CD also includes a section with information on all the Heathkit 23-series power supplies, such as schematics, chassis pictures, and a side-by-side comparison of the similarities and differences between the various models.  

See the KITS Page for prices and to order.

Contents copyright 2006-17 OldHeathkitParts - K8GNZ