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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Do you see that suspicious potting that squeezed outside the can in one of them?:.
I did not know where to start. Something was drawing more current than expected and the current-limit protection was tripping.
HP A SERVICE MANUAL Pdf Download.
There is a current sense resistor and this is what current looked at turn-on try:. No surpise, the secondary jacket was burned and touching the primary in one spot:.
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. The supply operates a high switching frequency and many parts of the circuit are shorted at DC, so I could not find this until I took both transformers out.
Showing Results for Keysight Technologies (Agilent HP) 70004A
High voltage, big and the troubleshooting will need to be done live. I built this “adapter” thing as a temporary ho, you too know what that means: 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.
You’ll probably want to use an isolation transformer and differential probes, and keep one hand on your pocket at all 70004. One day, it refused to turn on. This paid for itself in just this repair.
And a final picture of the twin transformers in 7004a working power supply. Can you tell one from the other? 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. Home Projects Music Photo. Could this be fixed?
Hewlett Packard HP a Display With b Optical Spectrum Analyzer | eBay
Knowing 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.
This board is a latter revision than the ones that appear on the schematics but there are not many changes.
The block diagram was invaluable, this switching power supplies are complex. I could see the power LED flash briefly upon turn-on and then This is the beast on the bench, that Yp looks very timidating to me.
70004A Color System Display
This last one required some improvisation because it is a quad-transistor instead of dual, and the DIP package is very different. 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.
I confessed before 7000a I killed a few components on the process, and I could not find replacements for some of them: You really need to know what you are doing before probing and testing a thing like this live.
Many suggested changing every capacitor in the board, something I was not going to do, I wanted to find what the fault really was all capacitors turned to be ok:. I used a thin teflon tube and a copper wire to recreate the four turns that form the secondary and guess what, it worked!! I was happy to find it actually worked I bought this cheap A color display as faulty.