Side project - repairing a Sony VP-5000 U-Matic video tape deck for the Space Force Museum

U-MATIC VIDEO MACHINES FOR PROFESSIONAL VIDEO WORK

The video recorder/playback universe spanned broadcast studio requirements with its 2" high speed tape down to home units such as VHS or Betamax with 1/2" wide tape. An intermediate level of quality (and expense) existed for professional but non-broadcast uses, such as the Sony U-Matic machines using 3/4" wide tape cassettes. 

EXAMINING THE MACHINE AND IDENTIFYING PARTS NEEDING REPLACEMENT

I opened this up and looked over the machine to see if there are any signs of damage or parts that definitely need replacement. I expect that the rubber parts are degraded. They didn't seem to be have hardened to develop cracks but I suspect their elasticity is lessened which would cause slippage for belts. 

EBAY KIT AVAILABLE FOR THE RUBBER BELTS AND TIRE

I found a kit with the rubber drive belts and the rubber tire for the main drive wheel which I purchased from eBay. This should give me replacements for all the worn parts, as these typically dry out on these machines (and on their Betamax smaller kin). The parts arrived and were ready for the restoration work. 

PURCHASE SERVICE MANUAL INCLUDING SCHEMATICS

Having the detailed schematics, adjustment procedures and other service information is essential to get a device like this operating properly. I received it and was ready to move forward with the restoration. 

CASSETTE LOADS BUT MACHINE GOES TO STANDBY, WON'T EJECT

Sliding the cassette into the front of the drive starts the load sequence, where it lowers the cassette into the machine, threads the tape around the head and should then be in stop mode waiting to play or perform other operations. Instead the deck enters Stand By mode which indicates some issue arose. Hitting Eject will not unload the tape, the machine remains in Stand By state. 

BELTS AND TIRE REPLACED, STILL GOES INTO STANDBY MODE

Once the new rubber was installed I tried again and did get the tape to load then let me start playback. However, attempting to return to Stop mode, rewind, fast forward or eject forced the machine into Stand By mode.

replaced main capstan motor

closing up the bottom side

Replaced belt that drives the threading motor and tire

Replaced cassette loading belt

DISCOVERED THE PINCH ROLLER ARM IS STICKING AS IT PIVOTS

There is an arm that moves the pinch roller on the tape to deliver controlled speed during playback, then moves out of the way for eject or fast tape movements. The arm stuck partway out, which the logic detected as a failure to complete its mechanical motion. There are many sensors in the deck to provide feedback to the logic state machines. 

I realized that it was just sticky old lubrication causing the problem. I partially disassembled it and dropped in some clock oil. The lever soon returned to free movement, so that the machine will now load, eject, play, rewind and all the other mechanical operations. 

NEXT UP - DISPLAYING IMAGE TO VERIFY THAT VIDEO AND AUDIO WORK

I will play the tape I brought with me from the museum and attempt to connect it to a monitor and audio system. The mechanisms might be moving tape just as intended but if the electronics can't extract the contents from the tapes it will still be broken. 

If it is working, I will make all the adjustments and lubricate it so that it is ready for use extracting content from the archives.