Tue, 03 Jan 2017 18:21:20 +0100
[blog] new series on the HP 3562A
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/content/hp3562a.rst Tue Jan 03 18:21:20 2017 +0100 @@ -0,0 +1,128 @@ +================================= + HP3562A Dynamic Signal Analyzer +================================= + +:Author: David Douard +:Category: Electronics +:Tags: HP3562A, repair, test equipment, DSA +:series: HP 3562A +:series_index: 1 + +One of my old test gears waiting for my attention in the cellar was a +HP 3562A Dynamic Signal Analyzer. Back then I bought this device +mainly for doing audio analysis (I was building my HiFi system, mostly +based on Nelson Pass' schematics), mainly to display spectrum +responses and compute THD and so. + +I did not reall know what this test equipment is capable of. But `Dave +Jones's video #528`_ (and several wonderful videos on `w2aew's +channel`_) gave me the desire of playing a bit more with this old but +very impressive HP3562A. + +.. _`Dave Jones's video #528`: https://www.youtube.com/watch?v=Y0jkPLuFdnM&t=1876s +.. _`w2aew's channel`: https://www.youtube.com/user/w2aew + + +Quick tour +========== + +Here is the beast: + +.. image:: {filename}images/hp3562a/front.jpg + +I said the beast, because despite being an amazing piece of test +equipment, it's also very big (576mm x 426mm x 222mm), very heavy +(26kg) and... unfortunately quite loud. + +My version of the instrument is rather "recent", and manuals available +on Keysight web site concern only the earliest models +(ref. 03563-90210) and are of poor quality, with missing pages etc. So +I bought the correct Service Manual (HP ref. 03562-90213) on ebay from +`Artek Media`_. + +.. _`Artek Media`: http://www.artekmedia.com/ + +Since it was on my "bench", I decided to see a bit inside, using the +occasion to investigate and fix the only real problem I have (as far +as I know) with my device: the dimm display. + +.. image:: {filename}images/hp3562a/front_open.jpg + +The unit consist in mostly 4 parts: + +- a big switching power supply (with huge capacitors) on the left side + of the enclosure, under the display, + +- the display unit: a very nice HP1435A Digital Display; we'll discuss + it a bit more later, + +- the digital section consisting in 8 boards (rear right), + +- the analog section consisting in 6 boards (front right). + + +The general block diagram: + +.. image:: {filename}images/hp3562a/hp3562a_block_diagram_new.png + :alt: General block diagram of the HP3562A + +The instrument is built around 2 buses: + +- the control bus which allows the main CPU to control all the + assemblies, and + +- the global bus which is used to transfer measurement data between + assemblies. + +In the HP3562A, the process control is distributed away from the +system CPU: each assembly has its own processor or state machine which +controls its local operations. The main CPU tells each assembly which +process to execute and monitors the overall functionning and data +processing of the instrument. + +For the record, the block diagram from Service Manual 03562-90219 +looks like: + +.. image:: {filename}images/hp3562a/block_diagram.png + :alt: General block diagram of the HP3562A from earliest Service Manual + + +Power Supply +============ + +.. image:: {filename}images/hp3562a/hp3562a_a18_psu_block_diagram.png + :alt: Block diagram of the switching power supply unit + + +.. image:: {filename}images/hp3562a/a18_psu.jpg + +The primary capacitors are huge Sprague caps (1400µF 250V): + +.. image:: {filename}images/hp3562a/caps.jpg + +The power line filter is also pretty impressive: + +.. image:: {filename}images/hp3562a/filter.jpg + +The PSU generates: + +- 5V @30A (!) + +- +/- 30V + +- +/- 15V + +- +8V + +- +2.6V + +The switching chopper runs at 128kHz and is regulted on the 5V output +rail by PWM of the primary transformer. All secondary voltages but the +5V are generated by linear regulators. + + +Next +==== + +In the `next part <{filename}hp3562a_2.rst>`_, we will describe the +Digital Section of the instrument.
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/content/hp3562a_2.rst Tue Jan 03 18:21:20 2017 +0100 @@ -0,0 +1,266 @@ +========================================== + HP3562A Dynamic Signal Analyzer - Part 2 +========================================== + +:Author: David Douard +:Category: Electronics +:Tags: HP3562A, repair, test equipment, DSA +:series: HP 3562A +:series_index: 2 + +This is the part 2 of the series about my +`HP 3562A Digital Signal Analyzer <{filename}hp3562a.rst>`_, +quickly describing the Digital Section of the instrument. + + +Digital Section +=============== + +The unit is quite capable, since the main CPU is a 68000 (not exactly +of small CPU for the time). + +.. image:: {filename}images/hp3562a/cpu.jpg + +The 8 boards are: + +- A1: Digital source and front-end interface (rev B, ref: 03562-66501) +- A2: CPU & GPIB controller (rev D, ref: 03562-66502) +- A3: Memory (rev B, ref: 03562-66538) +- A4: Local oscillator (rev C, ref: 03562-66504) +- A5: Digital filter (rev B, ref: 03562-66505) +- A6: Digital filter controller (rev D, ref: 03562-66506) +- A7: Floating Point Processor (FPP) (rev B, ref: 03562-66507) +- A9: FFT (rev B, ref: 03562-66509) + +The service manual also describes an A8 board with additional RAM, but +my device does not have such a board. It looks to me that my version +of the DSA has both extra ROM and RAM on the A3 memory board. + + +Digital Source +-------------- + +.. Note:: The Service Manual available on the net lacks a few pages in + the Digital Source section, so I do not have details on the + Timing Control section. + +.. image:: {filename}images/hp3562a/hp3562a_a1_block_diagram.png + :alt: Block diagram of the A1 Digital Source Board + +This board is mainly responsible for generating the digital signals +that are used as input for the source DAC. It generates all sort of +noise figures, bursts, sweeps, and so on. + +.. image:: {filename}images/hp3562a/a1_digital_source.jpg + +The Timing Control section looks like: + +.. image:: {filename}images/hp3562a/hp3562a_a1_timing_control_circuit.png + :alt: A1 Timing Control block diagram + +The Phase Resolution is used in external and internal triggered +measurements, ensuring that the phase of a triggered measurement is +accurate. Since the trigger moment does not always occur on a sample +and hold edge, there is a time delay and phase error in the data. +This phase resolution circuit counts the time between the samples and +a trigger. + +.. image:: {filename}images/hp3562a/hp3562a_a1_phase_resolution_circuit.png + :alt: A1 Phase Resolution block diagram + +The Burst Control circuit controls the burst length and generates the +pulse signal to the Local Oscillator (A4). It provides the gating +signal that gates the analog source on and off during the burst and +chirp modes. + +.. image:: {filename}images/hp3562a/hp3562a_a1_burst_control_circuit.png + :alt: A1 Burst Control block diagram + + +Other parts of this board are the LO Input Receiver that synchronizes +the local oscillator input data to the sample rate, the Multiplier +that multiply the LO data by the noise and send it to the analog +source, and the Noise Generator that produces binary random sequences +that is used for band-limited random noise and burst noise signals. + + +CPU +--- + +The processing unit is a MC68000. It aims at telling each assembly +which process to execute and monitor the overall functionning and data +processing of the instrument. + +.. image:: {filename}images/hp3562a/hp3562a_a2_block_diagram.png + +The main CPU board, with the beautiful MC68000P9 DIP64 package: + +.. image:: {filename}images/hp3562a/a2_cpu.jpg + +It comes with 2 populated M5M256BP static ram chips (32k x 8bits), for +the CPU, but seems to be capable of holding 4 more of them. The CPU +runs at 8MHz. + +There is also some ROM, the main "boot loader" program. Unfortunately, +neither of the ROM chips are mounted on sockets but are directly +soldered on the PCBs, so I did not took the risk of damaging one of +them by desoldering them for dumping their content. + +Most of the remaining of the circuit is to manage the global data bus, +the system bus, the IRQs and the GPIB bus. + +The blue connector is for the GPIB connector. + + +Memory +------ + +.. image:: {filename}images/hp3562a/a38_memory.jpg + +This board is described as an "extension of the read only memory of +the system CPU board" and read/write memory used by most of the other +assemblies. + +.. image:: {filename}images/hp3562a/hp3562a_a38_memory_block_diagram.png + +The ROM section stores most programs for the HP 3562A except the +startup routines (which are on the ROM ships of the A2 CPU +bloard). + +The board allows flexibility in the number and type of ROM chipes +used. ROM density is selected by placement of jumpers. + +.. image:: {filename}images/hp3562a/hp3562a_a38_rom_block_diagram.png + + +The RAM section of the assembly consist of 4 32k by 8 bits static RAM +chips as well as the arbitrer section which controls access requests +to the global RAM from six devices (FFT, both Digital Filters, +Display, FPP and the system CPU). + +.. image:: {filename}images/hp3562a/hp3562a_a38_ram_block_diagram.png + +The Display Controller section also lies on this A38 board. + +.. Note:: On older versions of the instruments, this board was + splitted in 2 (A3 and A8) and used less dense chips (thus, much more + chips). + + +Local Oscillator +---------------- + +The Local Oscillator produces digital sin and cosine signals +(synchronized with the sample rate). The sinusoidal signal is +generated from a table of values stored in the ROM. + +.. image:: {filename}images/hp3562a/hp3562a_a4_block_diagram.png + +.. image:: {filename}images/hp3562a/a4_loc.jpg + + + +Digital Filter and Digital Filter Controller +-------------------------------------------- + +The Digital Filter Assembly consists in both A5 and A6. It processes +two channels of serial data coming from the instrument front end (ADC) +ans stores the results in global RAM. Processing consists of +conversion from a serial format to a parallel format and, if required, +digital filtering or zoom (a combination of frequency shifting and +filtering). The processed data is transferred on the global data bus. + +.. figure:: {filename}images/hp3562a/a5_a6_block_diagram.png + :alt: Digital Filter Assembly block diagram + + Digital Filter Assembly block diagram. + +**Digital Filter:** Each digital filter consists of a control IC and 2 +filter ICs, one for the real data and one for the imaginary data. + +.. figure:: {filename}images/hp3562a/a6_zoom.png + :alt: Digital Filter for the zoom mode + + The Digital Filters are fed with a kind of LF I/Q demodulator, used + for zooming or actual digital filtering. + + +.. figure:: {filename}images/hp3562a/a5_filter.jpg + :alt: Picture of the A5 Digital Filter board + + Picture of the A5 Digital Filter board. + +.. figure:: {filename}images/hp3562a/hp3562a_a5_block_diagram.png + :alt: Digital Filter block diagram + + The A5 Digital Filter board block diagram. + + +**Clock Generator:** The clock generator creates two complementary clock +pulses from the 10.24MHz system clock. + +**Overload Detect:** The first 3 bits in the ADC serial data stream +contain overrange information that must be stripped off the serial +data. + + +.. figure:: {filename}images/hp3562a/a6_control.jpg + :alt: Picture of the A6 Digital Filter Control board + + Picture of the A6 Digital Filter Control board. + +.. figure:: {filename}images/hp3562a/a6_block_diagram.png + :alt: Digital Filter Controller block diagram + + The A6 Digital Filter Controller board block diagram. + + +FPP +--- + +The Floating Point Processor board is a fast arithmetic unit which +carries out real and complex arithmetic operations on blocks of data +stored in the global RAM. The processing ALUs are six AM2903 bit-slice +microprocessor ICs and one AM2910 microprogram +controller. Instructions are provided to the ALUs by an address +sequencer and seven microcode PROMs. + +.. figure:: {filename}images/hp3562a/hp3562a_a7_block_diagram.png + :alt: Floating Point Processor block diagram + :align: center + + Floating Point Processor block diagram. + +.. figure:: {filename}images/hp3562a/a7_fpp.jpg + :alt: Picture of the A7 FPP board + :align: center + + Picture of the A7 FPP board. + +This Floating Point Processor is capable of handling 16 bits integers, +32 bits and 64 bits floats. + + +FFT +--- + +.. image:: {filename}images/hp3562a/hp3562a_a9_block_diagram.png + +The FFT board performs windowing, FFT and Inverse FFT directly from +and to the RAM. +It's built around a TMS230 microprocessor runningat 5MHz + +.. image:: {filename}images/hp3562a/a9_fft.jpg + + +Keyboard +-------- + +.. image:: {filename}images/hp3562a/hp3562a_a15_block_diagram.png + + +Next +==== + +In the `next part <{filename}hp3562a_3.rst>`_, we will describe the +Analog Section of the instrument.
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/content/hp3562a_3.rst Tue Jan 03 18:21:20 2017 +0100 @@ -0,0 +1,103 @@ +========================================== + HP3562A Dynamic Signal Analyzer - Part 3 +========================================== + +:Author: David Douard +:Category: Electronics +:Tags: HP3562A, repair, test equipment, DSA +:series: HP 3562A +:series_index: 3 + +This is the part 3 of the series about my +`HP 3562A Digital Signal Analyzer <{filename}hp3562a.rst>`_, +quickly describing the Analog Section of the instrument. + + +Analog Section +============== + +The analog section consist in 6 boards: + +- A30: Analog Source +- A31: Trigger +- A32, A34: Input ADCs +- A33, A35: Input + +Analog Source +------------- + +.. image:: {filename}images/hp3562a/hp3562a_a30_block_diagram.png + +This board is mainly a DAC converting signal signal from the Digital +Source board (for sin waves). It also generates Pseudo Random Noise +and square waves (used for input calibration). + +The analog signal produced by the DAC is filtered by a 100kHz low pass +filter, then pass throught a step attenuator (5mV per step). The way +this is implemented is quite interesting: the analog signal from the +main DAC is used a reference voltage for a multiplying DAC. + +.. image:: {filename}images/hp3562a/a30_analog_source.jpg + +.. image:: {filename}images/hp3562a/a30_analog_source_dac.jpg + +Trigger +------- + +A first section of this board produces the trigger signal (for A1 +Digital Source and A5 Digital Filter boards) from one of the 4 +possible trigger sources: external, channel 1, channel 2 and the +calibration. + +.. image:: {filename}images/hp3562a/trigger_level.png + +The trigger clock circuit produces the 20.48MHz clock using a +VCXO. From this signal are derived the 10.24MHz clock used by many +boards (A1, A4, A5, A6, A30, A32 and A34) and the 256kHz clock signal +used as internal sample signal. + +When an external clock is provided, a PLL is used to lock this +20.48MHz. The external signal can be 1, 2, 5 or the standard 10MHz. + +.. image:: {filename}images/hp3562a/trigger_clock.png + +.. image:: {filename}images/hp3562a/a31_trigger.jpg + + +Input ADC +--------- + +.. image:: {filename}images/hp3562a/hp3562a_a32_block_diagram.png + + +The ADC board converts analog data from the input board into 13-bits +serial data words. The Analog to Digital convertion is done in 2 +passes by a 8-bits ADC. At each digitilization step, the signal value +is frozen by a Track and Hold circuit. This frozen value is digitized +(with a 8-bit resolution), then the digitized value is substracted +from the input (hold) signal and the result is multiplied then +digitized a second time to produce the remaining 5-bits of resolution. + +.. image:: {filename}images/hp3562a/a32_input_adc.jpg +.. image:: {filename}images/hp3562a/a32_input_adc_bb.jpg + + +Input +----- + +.. image:: {filename}images/hp3562a/hp3562a_a33_block_diagram.png + +The input assembly implements the voltage ranges and conditions the +input signal. It mostly consist in a pair switch attenuators (the +input is balanced), followed by a pair of amplifier/signal +conditionners. The balanced signal is then fed into a differential +amplifier followed by a amplifier and an attenuator. + +.. image:: {filename}images/hp3562a/a33_input.jpg + + +Next +==== + +In the `next part <{filename}hp3562a_4.rst>`_, we will describe the +HP 1345A Digital Display used in the instrument.
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/content/hp3562a_4.rst Tue Jan 03 18:21:20 2017 +0100 @@ -0,0 +1,126 @@ +========================================== + HP3562A Dynamic Signal Analyzer - Part 4 +========================================== + +:Author: David Douard +:Category: Electronics +:Tags: HP3562A, HP1345A, repair, test equipment, DSA +:series: HP 3562A +:series_index: 4 + +This is the part 4 of the series about my +`HP 3562A Digital Signal Analyzer <{filename}hp3562a.rst>`_, +quickly describing the HP 1345A Digital Display unit as well as +the repair I had to do on it. + + +Display +======= + +The display unit is a HP1345A Digital Display without the option 714 +(wich adds a 4K x 16 bits Vector Memory), so it must driven by a +dedicated display controller (which is on the A38 memory board): + +.. image:: {filename}images/hp3562a/a8_a17_display.png + +The unit is a 6 inch monochrome display producing true vector graphics +with a resolution of 2048x2018 points. It can display up to 3226 +inches of vectors at 60Hz. It also embeds a character generator. + +It's a true vector display; vectors are drawn by moving the CRT beam +on the screen (it's not a pixel based display). + +.. image:: {filename}images/hp3562a/hp1345a_raster_vector.png + +It can diplay: + +- solid lines +- solid lines with intensified end points +- short dashed lines +- long dashed lines +- dots at end points + +with 3 differents visible brightness levels. It also allows to specify +4 beam velocities: + +- 0.13cm/µs +- 0.25cm/µs +- 0.38cm/µs +- 0.51cm/µs + +Allowing more brightness control of the vectors. + +.. image:: {filename}images/hp3562a/hp1345a.jpg + + +If not connected with a controller, it shows a test pattern for +adjustments. + +.. image:: {filename}images/hp3562a/hp1345a_test_pattern.png + +The unit looks like: + +.. image:: {filename}images/hp3562a/hp1345a_side.jpg + +.. image:: {filename}images/hp3562a/hp1345a_side2.jpg + +.. image:: {filename}images/hp3562a/hp1345a_top.jpg + + +Adjustment and repair +--------------------- + +While the instrument was apart, I wanted to see if I can recalibrate +the display, especially try to adjust the overall brightness of the +CRT since mine is a bit dimm (I have to set the intensity knob FCW to +see the whole picture). I also wanted to improve a bit the focus and +precision of the lines. + +So I took the display unit off the instrument, which is +straighforward, powered it using my benchpower supplies, and began to +read the adjustment procedure and turn the pots, when suddenly the +display shut off. + +Using an ohmmeter, the diagnostic was easy: the +15v and -15v rails on +the A1 board were short. Fortunately, the schematic is available, so I +started to look for all decoupling capacitors (directly connected +between a power rail and the ground). It took me a little while before +identifing the real culprits, since the only solution to check them is +to desolder (at least one end): A1C45 and A1C48. + +.. image:: {filename}images/hp3562a/hp1345a_dead_caps.jpg + + +These 2 small (tantalum) caps near U3 were short. Not sure why they +died when I powered the display unit with my power supplies, maybe I +set them to a bit higher voltage then what the HP3562A generates. + +I replaced them with the closer spare I found (4.7µF tantalum caps), +and the Display Unit was up and running again. + +I knows these old tantalum caps are prone to fail, and I should +probably change them all, but I don't have enough spare for now. + +After that, I could resume my adjustement procedure. And indeed there +is an adjustment that allowed me to improve noticebly the brightness +of the screen (the Intensity Cut-Off Level). Now I can run my HP3562A +without the intensity knob FCW. + + +Brief description +----------------- + +.. image:: {filename}images/hp3562a/hp1345a_block_diagram.png + +.. image:: {filename}images/hp3562a/hp1345a_stroke_generator.png + + +.. image:: {filename}images/hp3562a/hp1345a_ramp_generator.png + + +.. image:: {filename}images/hp3562a/hp1345a_vector_processor.png + +.. image:: {filename}images/hp3562a/hp1345a_vpc_architecture.png + + +