EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: DominiqueB on March 19, 2020, 01:52:54 pm
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Hi all,
I contact you for the following.
I have one Wiltron Anritsu 68187B 60GHz generator having some problems.
When I got it, display was not good, and the CW had side bands. I changed the display, and changed the caps on the A18 PB Board ... and now display is perfect, and side bands are gone.
I have one problem left to solve . When running the Selftest program, I get an error "Error 106 Power Supply not locked" ... Looking the Service manual, I have checked the A6 Board which produces a good TTL 440kH as expected, used for locking the frequency of the A18 PS Board.
So the problem comes from the A18 Board. The PWM ic (ML4825) works fine, but the frequency of the oscillator is not locked. Instaed of being 440KHz, it is lower, at 320KHz. I have tried to replace the cap in the oscillator circuit, I can modify the frequency, by still not locked ...
So, my conclusion is that the PLL circuitery is broken, an I do not know why ...
> No schematics (if someone has the schematic, it wold be great, the Service Manual gives only blocks no components level)
> No obvious defective component
If someone has one A18 to trade, or schematics ... I am very interested.
Thanks for the reading and help.
Regards,
DominiqueB - F4HIJ