Wiltron / Anritsu 69147A 20 GHz Sweep Generator - Error 113 YIG Loop Osc Failed

[John_ITIC]

Hello, I'm going over my test instruments to bring bad ones back to life. This Wiltron 69147A was purchased on Ebay in 2019. The unit had some lock error but that was repaired before I purchased the unit. I have used the unit only a few times over the years and it started (a couple of years ago) having issues with the YIG locking over approximately 11 GHz (Error 113). When taking it out of storage this week, I noticed that the issue happened over many other bands. After having had the units on some time for trouble-shooting, the issue seems now permanent, except the first 10 seconds after turning it on. I'm suspecting something gets hot and fails somehow. And whatever it is, seems to degrade over time - even when the unit is not in use.

The closest service manual I could find is "Anritsu_Wiltron_680XXB_681XXB_SYNTHESIZED_CWSWEEP_GENERATORS_Service_Manual-10370-10262.pdf", here: http://ftb.ko4bb.com/getsimple/index.php?id=manuals&dir=Anritsu-Wiltron

That manual describes the Error 113 and has trouble-shooting diagrams. But, I noticed that my card layout is not the same as the 68xxxB units. So, before starting the trouble-shooting, I was wondering if anyone happens to have the proper 69xxxA service manual?

Note that the A4 block has a different style than the other blocks. Is this correct? Or was the A4 swapped out by the seller before I purchased the unit?

Thanks,
/John.

[John_ITIC]

Attached is the ERR 113 self test result.