EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: resistor on November 12, 2013, 08:21:00 pm
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I'm trying to repair an old HP 3456A meter. I've been working my way through the service manual, and have reached the point where I start needing to use a signature analyzer, which I don't have handy. I could go out and buy one, but it seems like I should be able to make out out of, say, an FPGA dev board. Unfortunately, I have only been able to find fairly sketchy descriptions of how they work. I know that it's basically a linear feedback shift register, but the only description of the tap points for the LFSR I've found is the diagram here: http://books.google.com/books?id=DSHSqWQXm3oC&pg=PA2104&lpg=PA2104&dq=signature+analyzer&source=bl&ots=o-PRBQMI2N&sig=OtgjLfzZFh-uePaNamST4AgKW3s&hl=en&sa=X&ei=JY2CUpqXLaWIiALctoCgDw&ved=0CHcQ6AEwDQ#v=onepage&q=signature%20analyzer&f=false (http://books.google.com/books?id=DSHSqWQXm3oC&pg=PA2104&lpg=PA2104&dq=signature+analyzer&source=bl&ots=o-PRBQMI2N&sig=OtgjLfzZFh-uePaNamST4AgKW3s&hl=en&sa=X&ei=JY2CUpqXLaWIiALctoCgDw&ved=0CHcQ6AEwDQ#v=onepage&q=signature%20analyzer&f=false)
Does anyone know if that set of tap points is correct, or know where I could find out?
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Look for a service manual for a Tek 308 Data Analyzer and look in the theory section. It has a description of how signature analysis works. The tap points are the same as your referenced diagram. The Tek 308 is compatible with the HP signature data.
You could also look for service manuals for HP 5004/5/6 signature analyzers. They should have theory sections.
You can generally find signature analyzers in the $50-100 range. Although it sounds like a fun project, is it really worth rolling your own? A presumably repairable hp 5004 just went for under $40 including shipping.