The 7 part technical manual
Thinking about Hewlett Packard and what Carly did to that company still makes me sad. I know, they mutated into Agilent, and equipment with the Agilent name can still be found (made in Malaysia now). It was a crime, what they did. And it was a tragedy, what was lost.
HP made the greatest technical manual that ever was. No company, before or since did anything even close to what those guys did for every single product. In those days the military forced them to do it in some cases. But now, the modern manuals are almost useless. Old HP manuals can be found free of charge at the Boat Anchor Manual Archivei. The 3400a is a great example from 1965.
HP’s first product was the 200CD and the story of HP is detailed in the book, “The HP Way” by David Packard. Copies are easy obtainable for about $4 plus shipping her at Abebooks.comii .
David Packard died in 1996 one year after the book was published.
The seven part manual consisted of the following sections:
Theory of operation (yes really)
With the information contained in the old seven part manual, someone could easily duplicate the device, but that was not the intention. Troubleshooting was so much easier. All parts were specified and easy to order. The customer could repair the gear. A Sailor at sea with a well stocked parts bin, could fix the gear underway. How I miss the 80’s…
In fact, the Navy taught us that “we were it”. No civilians or vendors at sea. You have to fix it. Skipper is depending on YOU. And of course, with a little good advice from the Chief, and our training and preparation at A school, we did fix the gear ourselves.
General information included the purpose of the equipment, a table of specifications, a photo of the unit and even a list of included items and optional accessories that can be ordered.
Installation included source power needed and advice on how to mount the unit in a rack and other details on installation.
Operating instructions begin with plugging the thing in and detail out every control, indicator and connector.
Theory of operation goes through each circuit, sometimes each component in great detail. Includes lots of diagrams and tables. If you want to know how things work read the old HP manuals. Navy ET school required this level of detail in the 80’s.
We studied communications and radar equipment and had to learn the purpose of each component and each circuit and even draw the block diagrams from memory. And then were tested on paper and also a practical test, troubleshooting the gear with instructor inserted faults. A failure to score nearly perfect on the test, or to find the inserted fault resulted in a trip to the Chiefs office and maybe to the fleet.
The maintenance section outlines the performance tests to determine if the device is working correctly and meets published specifications. This includes step by step instructions for each test and diagrams for each test setup. Also included are adjustment and calibration procedures again in great detail, exactly how to do it.
Troubleshooting is also covered in the maintenance section. There are procedures, troubleshooting “tree” diagrams, and schematics with test points and diagrams showing what the signal should look like at various points or voltage values.
In the schematic section are the schematics with circles and arrows and helpful notes, all components clearly labeled and diagrams of each circuit board showing the location of the components on the board.
The replaceable parts section has a giant table showing all the parts and giving the manufacturers part number and sometimes even the national stock number (military stock system) and also the supplier or manufacturer of each part. It was organized by assembly. In general each board is a separate assembly marked A1, A2…An. There is a system of assemblies within assemblies so that if you have a resistor within an assembly within an assembly within the whole unit it would be labeled something like A1A3A1R1. Also you will find photos with circles and arrows pointing to each part and a table giving the part numbers for each part.
Functional block diagrams
A functional block diagram is a generic sort of block diagram to help the technician to perceive the overall big picture view of the equipment or system.
A troubleshooting tree is basically a flow chart that tells you what to check and how to proceed based on the results of each test. At the end, hopefully you find the fault.
6 step (US Navy) troubleshooting
Most technicians, over time develop a style of troubleshooting that works for them. In the beginning of training the Navy provides the novice with the following steps to facilitate development of a troubleshooting style. At ET school during the practice troubleshooting events a form was filled out with notes about how each step was accomplished in the specific case.
This is also known as “logical troubleshooting” which is the opposite of easter-egging.
Listing of the probable faulty functions
Localizing the faulty function
Localizing trouble to the circuit
Symptom Recognition: Do not believe the witness, test the gear yourself. Simply determine whether there is in fact a problem or not.
At NAVCOMSTA Stockton, very early in my career I went to check on a trouble call involving a broken document shredder. Following the above steps, of course the first step is to plug in that shredder and make sure it does not work. So right there, back in the crypto room by the STE (Shade Tree Electronics) shop, I plugged it in. The lights flickered, all the KG13s went dark. Shortly there was a note coming across on the order wire from the duty Chief “what was the previous rate of the ET that plugged in that shredder?”. Well, I was not busted. But it was clearly the wrong place to plug that thing in.
Symptom Elaboration: Here is where you use what you know about the gear, plus your senses to further narrow the possibilities of what could be wrong. Adjust the controls, observe the lights and indicators, listen for normal sounds, beeps, fan noise. Check the cribs (is it just past raday?). Observe any built in test equipment such as meters. Turn on the echo box and check the ring time in the case of radar. Are the controls set correctly? Run through the startup procedure yourself.
Listing the probably faulty functions: This step is a mental exercise where you put together the symptoms that you observed in the previous steps and on paper speculate about what it could be and rule out what it could not be. For example, if you have a radio, FM works and AM does not. You would use what you know and your block diagram. The FM radio shares the audio amp with the AM radio. Common to both, can not be that. Both use the same power supply, trouble can not be there. On the front end they have different antennas and tuner parts. The trouble might be there.
Here is another real world example. Calibrating an Astro-Med DASH18X. You find that the inputs all check ok until the very end when the thermocouple channels are tested. All 18 of the thermocouple channels are pegged negative, completely inoperative. Previously, the same inputs, set up for differential measurements worked fine. For the last step, those inputs are reconfigured for temperature measurement as thermocouple inputs.
So, what could it be? Well, there are three separate input cards and 18 channels. It is normal to see one or two that are out, maybe one whole card, 6 channels out, but not all of them. What could be common to all eighteen TC channels and yet not cause a problem with the differential inputs?
For any device used to read thermocouples a reference junction is required. The DASH18X has a thermistor probe sticking out of the cabinet. Turns out, pressing on the thermistor caused the trouble to come and go. Carefully removing the heat shrink tubing reveals broken wires. Mystery solved.
Localize the faulty function: Here you may perform additional tests to narrow down the trouble to the single block or function on the block diagram. This is the first step where test equipment is used. To determine whether the trouble is the antenna or the front end tuner you might patch the antenna to another radio to see if that works. Or substitute a signal generator for the antenna.
Localizing trouble to the circuit: Here you further narrow the trouble to the circuit within the block or the function. Or inject a signal to the radio at the antenna connector and do some signal tracing.
Failure Analysis: Now is the sanity check. Does the problem that you found (and fixed or ordered parts to fix) fit with the symptoms that you observed? Does it all make sense? And, is there something you could do to prevent it from happening again? Could you use a larger wattage resistor and write a benesug to create a field change and fix every unit in the fleet? And the Admiral likes the Benesug so much that he writes you a big bonus check and CAPs you to the next higher rank! Oooorahh.
Astro-Med DASH8HF on power up has an error “Capture drive error 8”. No technical data in the book on what error 8 is…
Step 1: Start it again, verify the error is still present.
Step 2: Try to format or view files on the capture drive?
Step 3: What could it be? Well, could be the capture (data) drive itself. Could be the data cable, power cable or main board or the power supply. Other drives are working though so probably not the power supply.
Step 4: Open the unit up to gain access to the drive. Feel the drive, is there vibration when is should be running? Notice, power cables routed from different connectors on the same board. To narrow the possibilities test the drive in another unit or substitute a spare drive. Not the drive. Replace the data cable. Not the data cable. Try using a Y shaped power cable to route power from the CD drive and see if the power cable is the problem. AHA, now it works.
Your most important test equipment is your brain guided by experience. Every time you solve a tough troubleshooting problem you get faster, smarter, more efficient at troubleshooting.
I have an old Fluke model 11 for my toolbox meter. I like it because it has a capacitance function which allows me to test and identify capacitor values. And of course it is great for resistance and voltage checks also.
Another tool I like is the Huntron Tracker. You can make your own, (called an octopus) by following the information in the Navy technicians handbook and use it with a simple analog oscilloscope.
Diagnostics/ Built in TE