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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Could this be fixed? Can you tell one from the other? You’ll probably want to use an isolation transformer and differential probes, and keep one hand on your pocket at all times.
You can see the power supply slowly increasing the current at turn on until it gets too high before it starts regulating the voltage, and quits.
There is no way to check one of the blocks of the power supply alone, you have to give it power and hope for the best. This paid for itself in just this repair. Knowing I had nothing to loose, I went and opened the transformer can with a Dremel, and removed the resin with hot air 700044a tweezers, carefully to not damage the 70004aa.
There is a current sense resistor and this is what current looked at turn-on try:.
Do you see that suspicious potting that squeezed outside the can in one of them?:. This is the beast on the bench, that PCB looks very timidating ho me.
The block diagram was invaluable, this switching power supplies are complex. I did not know where to start.
HP 70004a Spectrum Analyzer Display Mainframe W/ HP 70841b Pattern Generator
I confessed before that I killed a few components on the process, and I could not find replacements for some of them: High voltage, big and the troubleshooting will need to be done live.
The supply operates a high switching frequency and many parts of the circuit are shorted at DC, so 770004a 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: No surpise, the secondary jacket was burned and touching the primary in one spot:. You really need to know what you are doing before probing and testing a thing like this live.
I was happy to find it actually worked One day, it refused to turn on.
HP a Spectrum Analyzer Display Mainframe W/ HP b Pattern Generator | eBay
I could see the 07004a LED flash briefly upon turn-on and then And a final picture of the twin transformers in the working power supply.
Something was drawing more current than expected and the current-limit protection was tripping. I bought this cheap A color display as faulty. Many suggested changing every capacitor in the board, something I was not going to do, I wanted to 70004 what the fault really was all capacitors turned to be ok:. Home Projects Music Yp. After many hours of testing and probing, and and few components that exploded in the process most times my fault I found there was a transformer with a 14 ohm leak between primary and secondary.
I used a thin teflon tube and a copper wire to recreate the four turns that form the secondary and guess what, it worked!!
Keysight Technologies (Agilent HP) A used or new for sale at used-line
This last one required some improvisation because it is a quad-transistor instead of dual, and the DIP package is very different. This board is a latter revision than the ones 7004a appear on the schematics but there are not many changes.
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.