Hello,
I've got my RF Signal generator HP8646B in trouble.
It display at power on : 616 AM Modulation path failure.
According to the troubleshooting section of the service manual : Either the main board A3 or the detector has failed.
As it's still doing AM fine, i think something around AM detector has failed or partialy failed. May be the AM diagnostic side is faulty...
I've teardown the unit. Fortunately for me the power supply is in bad shape, full of dirt and some resistors are almost fried. So i will repair the power supply first.
For AM side, as there is no schematic of the A3 mother board on the web, i don't know where i must have a look first :
- Cabling
- Follow the AM signal path trying to find a kind of detector
Any advices are welcome.
Thanks