The Sony BVU-950 series was the flagship series for Sony Umatic SP. Produced in the 1980’s and 1990’s, these were the last and best Sony Umatic SP series made for the broadcast market. There are several mechanical similarities to the Sony VO-9850 series, but the BVU-950 series boasts much more advanced electronics and higher performance. There are 3 models in the Sony BVU-950 series:

• BVU-950 RECORDER – PLAYER – EDITOR: This is the most popular model. It is a full featured recorder with editing capabilities, but it can easily be replaced with BVU-900 if all you need is playback for digitizing Umatic or Umatic SP tapes. Precision Video Service has a fully restored BVU-950 for use in tape digitizing services.

• BVU-920 PLAYER (WITH DYNAMIC TRACKING): This model is less common. What makes it unique is the high performance ‘microprocessor controlled’ Dynamic Tracking system for a perfectly clear picture during off-speed playback and pause. The BVU-920 included the BKU-901 TBC & BKU-902 CNR options as standard equipment, unlike the BVU-900 & BVU-950 in which these were optional boards. Since the BVU-920 has Dynamic Tracking, there is no need for a tracking control. The BVU-920 is well suited to playback difficult tapes because it can sometimes adapt to tapes that were recorded with bad tracking alignment. Precision Video Service has two BVU-920’s on hand to support Umatic tape digitizing work.

• BVU-900 PLAYER: is the basic player of the series. This model works just as well as the BVU-950 and is highly reliable. It has the same high performance as the BVU-920 & BVU-950.

Options:

• BKU-901 internal TBC (timebase corrector), and BKU-902 internal CNR (chroma noise reduction add-on for internal TBC).

• BVR-55 TBC remote (allows control of the built-in TBC).

• BKU-905 internal time code generator/reader.

Sony BKU-901 TBC & BKU-902 CNR boards on an extender board in a Sony BVU-950. These boards were optional for the BVU-950 & BVU-900, and were standard in the BVU-920.

Error codes:

Error-02 and Error-05 are probably the most common errors in these machines. Both errors can be caused by a wide variety of tape issues including sticky tape (sometimes called sticky shed), moldy tape, contaminated tape path, broken tape, damaged cassette, etc. If you encounter these errors, I recommend to thoroughly clean the entire tape path. That includes EVERYTHING the tape touches. Every tape guide, roller, stationary head, upper and lower video head drum, etc. All of it. Then try the machine with a known good test tape.

Troubleshooting & repair:

Common problems with BVU-950 series include:

• Tearing and/or streaking in video – this can be caused by dirty or worn out video heads. Clean the video heads and check again. Also check with a known good tape. If that doesn’t help, the next thing I would do in the shop is to measure the head tip protrusion to assess wear condition. Brand new heads read 75 microns, worn out heads read 32 microns. Anything less than about 35 microns I recommend the heads to be replaced. If head protrusion is good, next I would check the video head frequency response using an oscilloscope and the RF sweep segment of the alignment tape. This proves if the heads are performing properly. Sometimes heads fail in this way, well before they are actually worn out. Lastly, it could be the RF EQ/gain adjustments have been tampered with. If so, these are very tricky adjustments and you will need to send it in se we can put things right.

• Jumpy video – This could be bad tape path alignment, or low tape tension, or worn video heads. Best to use an oscilloscope to check the RF envelope for low tape RF at the drum entrance. The vertical sync is at the top of the video frame, and that coincides with the point where the rotating heads first contact the tape. If the vertical sync is not reproduced properly this will result in the picture losing vertical sync and jumping.

• Tracking lines in video – a common problem here is possibly a bent entrance guide in tape path alignment. This sometimes happens when the tape snaps hard in fast forward or rewind modes. The guide gets bent out of standard alignment. To fix this correctly requires a tracking alignment tape and an oscilloscope.

• Tape creasing when using reverse search – worn or mis-aligned pinch roller or turnaround guide. This might require pinch roller replacement, or alignment of the turnaround guide. The guide can be bent when tape snaps. There are special procedures to get this tape guide aligned correctly, this should be done by an engineer.

• Distorted or missing video – bad capacitors on DM board or TBC board. In the shop this involves locating and replacing the bad capacitors and inspecting the circuit board for possible circuit board damage from leaking capacitors.

• Audio problems – tape path alignment error or bad capacitors on audio board(s). This alignment error can also be related to the bent turnaround guide.

• Won’t accept tapes – broken flex wires in cassette elevator. Replace these fragile wires with suitable high strand count flexible wire.

  Please contact me for troubleshooting and remote diagnostic assistance.

Precision Video Service offers full repair service for Sony BVU-950 series Umatic decks. We are well equipped with tools, jigs, alignment tapes, test equipment, service manuals, and 35+ years experience to troubleshoot and repair many types of video tape equipment.