HP 5300B Counter Plug-On modules

Cleaning up and look­ing at a bunch of plug-on mod­ules for my Hewlett Packard 5300B main­frame mod­ules, after pur­chas­ing a new unit. It seems that I am start­ing to col­lect quite the range of mod­ules for my HP 5300 sys­tems since my orig­i­nal 5300B Measuring System back in 2017.

HP 5300B with 5308A 75MHz Timer/Counter and 5312A HP-IB Interface modules

The newest addi­tion to my HP 5300 series mod­ules is the 5312A HP-IB Interface plug-between mod­ule. It is also referred to as the “ASCII Interface” mod­ule, and plugs between the 5300B main­frame and asso­ci­at­ed plug-on mod­ules to pro­vide an inter­face to the Hewlett-Packard Interface Bus (HPIB). The avail­able data includes: all sig­nif­i­cant dig­its, expo­nent, over­flow, and func­tion codes. It is capa­ble of trans­fer­ring up to 40 mea­sure­ments per sec­ond depend­ing on the plug-on mod­ule attached. It is not com­pat­i­ble with the 5300A mainframe.

HP 5312A HP-IB/ASCII Interface plug-between mod­ule front panel
Hewlett Packard 5312A top board view

The board to board con­nec­tor is hand sol­dered to the PCB using short wires for the need­ed con­nec­tions. The oper­a­tion of the 5312A is con­trolled by an Algorithmic State Machine (ASM), and uses a 4K ROM to out­put 16 bits to con­trol the ASM.

Bottom of HP 5312A board with 4K ROM IC at cen­ter (white 28-pin)

The back pan­el includes the HP-IB (GPIB) con­nec­tor and a DIP switch for select­ing the address, mode, shield enable, and a “self check” function.

Back pan­el of HP 5312A HP-IB Interface

Another plug-on mod­ule that I have sev­er­al of is the HP 5308A 75MHz Timer/Counter plug-on mod­ule. It is anoth­er mod­ule that is only com­pat­i­ble with the 5300B main­frame mod­ule. It has two chan­nels and a SEP-CHK-COM switch that con­nects the Channel B con­nec­tor on the front pan­el to both A & B ampli­fi­er cir­cuits in par­al­lel. There are lots of func­tions includ­ing a self-check and stopwatch.

HP 5308A 75 MHz Timer/Counter front panel
HP 5308A 75 MHz Timer/Counter board top view

The com­bined front pan­el switch­es are used to select the address of ROM U26 which then set 16 out­put lines, which con­trol the sig­nal path and log­ic includ­ing the dec­i­mal point, annun­ci­a­tors, and res­o­lu­tion. The 5308A also fea­tures an auto­mat­ic time base mode.

HP 5308A 75 MHz Timer/Counter board bot­tom view
HP 5308A 75 MHz Timer/Counter back pan­el switch and BNC connectors

Both of my 5308A mod­ules have worked well with no issues oth­er than requir­ing a good clean­ing of the switch­es with DeoxIT con­tact clean­er to restore full functionality.

Connected to my 5300A main­frame is a HP 5302A 50 MHz Universal Counter plug-in mod­ule. It is a much sim­pler counter than the oth­er mod­ules that I have, but still has some good fea­tures. The A chan­nel accepts up to a 50 MHz sig­nal, while the B chan­nel has a max­i­mum of 10 MHz input fre­quen­cy. It has fre­quen­cy, peri­od, time inter­val, ratio, and check functions.

Hewlett Packard 5302A 50 MHz Counter front panel
HP 5302A 50 MHz Counter top view of cir­cuit board

Compared to the high­er fre­quen­cy capa­ble mod­ules, the cir­cuit board is a much sim­pler design. The input cir­cuit­ry for chan­nels B and A are locat­ed in the upper-left area of the cir­cuit board in the image below, and show a sim­i­lar com­po­nent lay­out for each channel.

HP 5302A 50 MHz Counter bot­tom view of cir­cuit board
HP 5302A 50 MHz Counter side view of cir­cuit board
HP 5302A 50 MHz Counter back pan­el with Gate Out connector

My recent pur­chase includ­ed a 5300B main­frame mod­ule that is a 1824 series unit with 1974 dat­ed com­po­nents installed. My oth­er two 5300b“s are new­er 1452 and 1704 series units. I noticed that the old­er series 1824 unit had some dif­fer­ent brand­ed, col­ored, and shaped com­po­nents used in it, main­ly capacitors.

Hewlett Packard 5300B main­frame com­po­nent changes
Hewlett Packard 5300B main­frame side­view of new OEM components

I real­ly have been enjoy­ing repair­ing and learn­ing about the HP 5300 sys­tems over the past few years. Luckily doc­u­men­ta­tion is still avail­able for all the mod­ules I cur­rent­ly have.
I am still look­ing for a 5306A Multimeter Counter, and a 5307A High Resolution Counter mod­ule which should both also be a learn­ing experience.

5 Replies to “HP 5300B Counter Plug-On modules”

  1. Hi,congratulations on your work. I have an HP 5308, which has a faulty IC. Part No. 1820–1565 but I can’t find it. I have to find a cor­re­spon­dent, can you help me out.

    1. Hi Gianni,
      Looks like IC U2 (1820–1565) is a dual ECL Schmitt trigger.
      The clos­est mod­ern equiv­a­lent that I have found is a Maxim MAX9693, but it has a dif­fer­ent pinout and would need to be adapt­ed to work in the circuit.
      Greg (Barbouri)
      HP 1820-1565 in 5308A

  2. Hello Mr. Barbouri, I am in pos­ses­sion of a counter/timer type 5308A which unfor­tu­nate­ly does not work well, because it takes a long time to dis­play a fre­quen­cy and when it wants. Do you have the schemat­ics for mod­ules 5300 and 5308A to help me with my repair? I can’t find these schemat­ics because this mate­r­i­al is no longer tracked and has become obso­lete. Thank you very much in advance for your response and con­grat­u­late you on your high-qual­i­ty work. John

    1. Hi Jean,
      The 5308A man­u­al is avail­able for pur­chase from http://www.artekmedia.com, which is where I pur­chased my copy of the manual.
      The 5300A and 5300B dis­play main­frame man­u­als are avail­able online from https://www.keysight.com/us/en/assets/9018–05899/user-manuals/9018–05899.pdf
      and https://xdevs.com/doc/HP_Agilent_Keysight/HP%205300B%2C%205310A%20%20Operating%20%26%20Service.pdf
      Also be sure and check­out my post on build­ing the 5300 test / diag­nos­tics card:
      Hewlett Packard 10548A Diagnostic Service Kit

      Greg (Barbouri)

  3. Hi Greg, thanks to your invalu­able help, I have found some inter­est­ing doc­u­ments on the 5300 B mod­ule that is part of my device. For the oth­er part (5308A), I’ll see if it’s worth order­ing the doc­u­men­ta­tion, because indeed these mod­ules are dif­fi­cult to access and not so easy to repair. I looked at your page: Hewlett Packard 10548A Diagnostic Service Kit and indeed, I under­stood that you need some diag­nos­tic tools to make a suc­cess­ful repair.
    Your web­site is real­ly good and very well done and it is a great help for repairs, ideas for real­iza­tions and infor­ma­tion. It’s per­fect and amaz­ing. Thanks again Greg for your help. John

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