Find great deals for HP a Spectrum Analyzer Display Mainframe W/ HP b Pattern Generator. Shop with confidence on eBay!. Find great deals for Hewlett Packard HP a Display With b Optical Spectrum Analyzer. Shop with confidence on eBay!. Software and documentation supplied. This service guide is part of an Option OB3 package which includes: HP A Service Guide. HP A Component.
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The block diagram was invaluable, this switching power supplies are complex. I was lucky to have bought a FLUKE D differential voltage probe this year at Friedrichshafen to the nice guy with grey hair and glasses that sells mostly Fluke stuff.
Can you tell one from the other? Many suggested changing every capacitor in the board, something Hhp was not going to do, I wanted to find what the fault really was all capacitors turned to be ok:. This board is a latter revision than the ones that appear on the schematics but there are not many changes.
I confessed before that I killed a few components on the process, and I could not find replacements for some of them: Home Projects Music Photo. You can see the power supply slowly increasing the current at turn on until it gets too high before it starts yp the voltage, and quits.
I bought this cheap A color display as faulty. One day, it refused to turn on.
HP A SERVICE MANUAL Pdf Download.
I could see the power LED flash briefly upon turn-on and then The supply operates a high switching frequency and h; parts of the circuit are shorted at DC, so I could not find this until I took both transformers out. I built this “adapter” thing as a temporary solution, you too know what that means: There is a current sense resistor and this is what current looked at turn-on try:. High voltage, big and the troubleshooting will need to be done live. This is the beast on the bench, that PCB looks very timidating to me.
Hewlett Packard HP 70004a Display With 70950b Optical Spectrum Analyzer
No surpise, the secondary jacket was burned and touching the primary in one spot:. You really need to know jp you are doing before probing and testing a thing like this live.
You’ll probably want to 07004a an isolation transformer and differential probes, and keep one hand on your pocket at all times. Something was drawing more current than expected and the current-limit protection was tripping.
This last one required some improvisation because it is a quad-transistor instead of dual, and the DIP package is very different. 700044a I had nothing to loose, I went and opened the transformer can with a Dremel, and removed the resin with hot air and tweezers, carefully to not damage the windings.
HP a Spectrum Analyzer Display Mainframe W/ HP b Pattern Generator | eBay
And a final picture of the gp transformers in the working power supply. Could this be fixed? I was happy to find it actually worked I did not know where to start. I used a thin teflon tube and a copper wire to recreate the four turns that form the secondary and guess what, it worked!!
There is 70004s way to check one of the blocks of the power supply alone, you have to give it power and hope for the best. Do you see that suspicious potting that squeezed outside the can in one of them?:.
After many hours of testing and probing, and and few components that exploded in the 770004a most times my fault I found there was a transformer with a 14 ohm leak between primary and secondary. This paid for itself in just this repair.