After spending many hours working on my Hewlett Packard 5300 series measuring systems, I decided to remake my own version of the HP 10548A diagnostic service kit.

The HP 5300 series measuring system is not an easy system to troubleshoot and work on. Typically there are two modules with a 50 pin connector between them. The upper mainframe display module includes the power supply, 10 MHz oscillator, counter, time base divider, control circuits, and digital display.
The lower plug-on module contains circuitry for signal input, attenuating, amplification, mode selection control, and annunciator control.
When connected together, only one side of each module’s circuit board is easily accessible for troubleshooting. Generally neither module will function without being connected to it’s other halve.
The HP diagnostic service kit allows a technician to service the 5300 series mainframe display module without a plug-on module attached. It also provides easy access to many of the control and data signals on the module.
Based on the HP 5300B service manual, I designed a circuit board based on the information found in tables 5–2 thru 5–4. I decided not to duplicate the original diagnostic service kit, and to build a compact board that uses jumpers and a switch to accomplish the connections provided by the original four test cards.
I had already made a similar type of board for the HP 3470 series display modules. Instead of turret terminals this board uses sockets compatible with standard breadboard jumpers to make up the required connections for each of the tests.
Shortly after sending off the board design to be produced by OSH Park, I came across an Ebay listing for an original HP diagnostic interface connector and two test cards. They are now mine!

The interface connector 05300–60004 converts from the Centronics style 50 pin connector found on the 5300 series mainframe display module and a 44 pin female socket for the diagnostic test cards.


Each diagnostic card has four board edge connectors for each of the four tests per card.
Diagnostic card A checks the display circuitry using tests 1–4. Diagnostic card B checks the inputs and outputs of the various modes of operation, the annunciators and decimal points using tests 5–8. Diagnostic card C and D tests 9–16 test the time base circuitry and decade counter.


Unfortunately I was not able to find test cards A and C, but it was interesting to see how HP implemented the card jumpers on the two cards I received.
On my diagnostic card I decided to use a rotary switch for the annunciator and decimal point indicator test, where on test card B test 8, HP decided to use jumpers for testing those functions.


On my diagnostic card I added turret terminals for ground, reset, and the five power supply voltages available on the connector. The 3.5 volt supply doesn’t connect to the connector as it is only used for powering the front panel display, and must be checked from the test point on the mainframe module.


I printed the test jumper positions on the back of the card based on the information provided in the HP 5300B service manual. For some reason test 5 isn’t included in the 5300B manual, but is included in the 5300A manual. In the EagleCAD files for revision B, I added an extra ground (4–7) to accommodate test #5’s need for another ground jumper.
I also added an onboard power switch for another method of switching power along with the modules rotary power switch. Both switches must be enabled to power up the module.

So far the new test card has worked well and has been used on a HP 5300A and 5300B for troubleshooting.

EagleCAD V7.7 schematic and board Rev. B ZIP file
Bill Of Materials BOM for Test Card Revision B
OSH Park shared project page for 5300 Test Card Rev B