UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Sony U-matic VO5850 tracking and/or sync track issue

collisr · 3rd Jun 2021, 10:51 am

Quick update for everyone:

Started the further diagnosing by following the capstan free speed adjustment supplied by Fivos. The total lack of wave at this test point implied there were no sync/ctrl pulses being received to the servo board.

I thought it unlikely the audio-ctrl head was at fault, so I replaced the entire servo board from a known good machine and the ctrl pulses into IC7 were all present and correct.

However, with this "borrowed" board, I am seeing a new problem. The tracking/RF-level meter continues to drop to zero every 10 seconds or so but the video output on the monitor now scrolls continually.

There are clearly multiple faults going on here and I'm going to put this machine back in the "tricky" pile for now.

Thanks for all your help though.

Rob

3rd Jun 2021, 10:51 am	#6
collisr Pentode Join Date: Oct 2016 Location: Ware, Herts, UK Posts: 171	Re: Sony U-matic VO5850 tracking and/or sync track issue Quick update for everyone: Started the further diagnosing by following the capstan free speed adjustment supplied by Fivos. The total lack of wave at this test point implied there were no sync/ctrl pulses being received to the servo board. I thought it unlikely the audio-ctrl head was at fault, so I replaced the entire servo board from a known good machine and the ctrl pulses into IC7 were all present and correct. However, with this "borrowed" board, I am seeing a new problem. The tracking/RF-level meter continues to drop to zero every 10 seconds or so but the video output on the monitor now scrolls continually. There are clearly multiple faults going on here and I'm going to put this machine back in the "tricky" pile for now. Thanks for all your help though. Rob