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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 14th Jun 2015, 7:11 pm   #1
HurtyAC
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Default Sony SL-C7 Rebuild

Hi All, My first rebuild post on this website so appologies if I don't quite get this right. I thought it was time to get my Sony SL-C7UB which I bought when I worked for Sony as a bench engineer in London in 1981/82. I also bought a second unit off ebay and an SL-C5UB (I like a challenge!). This is the rebuild of my origional SL-C7. Before you apply power to these machines you will need to replace the two 4.7uF 350 volt capacitors (see photo) in the switch mode power supply or you run the risk of blowing the switching transistors! mine had both leaked and where dry.
The next major work that will be required will be a re-build of the clock/timer unit. As mentioned on this site before, all the switches will have perished and will need replacing, there are 19 in total and 12mm tactile switches make a perfect replacement. The next job is the battery clock invertor board which has a nicad battery which will have gassed causing damage to the PCB traces and bad corrosion to the boards and flexable interconnection cables which will be leaking accross each other. The only way to fix this is to remove the cables and battery from the boards, clean the boards with toothbrush and water, re-trim the cable ends then re-solder all of them back. At this stage you should be ready to apply power and hopfully be greeted with a working clock and timer board with no errors on the clock display and no leds "on" that shoudn't be.
Next job is to clean and/or replace as nessesary any belts and pulley assemblys that require it and free any "sticky" arms paying attention to the back tension arm itself. This done a tape was then presented to the machine which then gave the "slow loading" problem which was in this case down to the lower capstan motor bearing being worn. Had to fit a new capstan motor which is not the easiest job due to its location had having to move the upper wireing loom out of the way. This complete we then obtained a horizontally jittering picture and capstan that would not properly lock. C11 (0.47uF) and C41 (0.33uF) on the servo board where replaced and servo alignment carried out and we then had good pictures. When I retired this machine it had the classic problem of output mutting at the beginning of tapes which is caused by the ACE head assembly (Audio Control Track and Audio Erase) being worn causing changing CTL pulse level to be recorded or played back. One was obtained (from America) and has now been fitted. You have to know what you are doing when replacing this item as it affects not only the audio and CTL but the whole tape path! Machine is now up and running again. I'm now desperately searching for an origional alignment tape as this is the correct way to get the ACE head assembly in the correct place. You have to watch out for the interaction of the CTL assembly position with the electronic tracking centre position adjustment. Enjoy the pictures, there are more if requested.
Adrian
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Old 14th Jun 2015, 8:57 pm   #2
Freya
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Default Re: Sony SL-C7 Rebuild

A good result after all that work, well done.
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_________"It`s only an old telly" ___

Last edited by AC/HL; 14th Jun 2015 at 11:53 pm. Reason: Forum rules
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Old 15th Jun 2015, 9:35 am   #3
steptoesyard
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Default Re: Sony SL-C7 Rebuild

Interesting post.

Hope you don`t mind me asking, but where did you get those switches from? My C7 needs a switch transplant and that will make it a perfect machine!
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Old 15th Jun 2015, 10:58 am   #4
HurtyAC
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Default Re: Sony SL-C7 Rebuild

Hi Steptoe I've sent you a PM on the item but they are on ebay as tactile switch 6mm X 6mm X 12mm. You mount them diagonally with opposite corner legs and cut the other two legs off close to the body. See the photograph.
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Old 17th Jun 2015, 3:43 pm   #5
Libratron
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Default Re: Sony SL-C7 Rebuild

Thanks Hurty for this Precious information for the SL-C7.

Libra
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Old 22nd Jun 2015, 12:47 pm   #6
Sanbeta
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Default Re: Sony SL-C7 Rebuild

Hurty

Remember too most pre recorded Beta tapes were recorded using Sony slave machines.
You can also set up the CTRL position using this as reference.
Having access to another well set up beta vcr also helps as when playing back any recordings made on the C7 on another Beta, you can see how far out the CTRL adjustment is as it should be near perfect tracking results when both are set up A1.In other words turning the tracking control left and right you should get minimal disturbance to the picture on both recordings and playback.It should be perfect when at the center.

.......Kevin
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Old 22nd Jun 2015, 8:30 pm   #7
gec2110
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Default Re: Sony SL-C7 Rebuild

These were a good machine, and much better than the JVC 7700 but both were very complex well done in getting it working looks good
The best vcr at the time when new
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Old 23rd Jun 2015, 11:04 pm   #8
HurtyAC
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Default Re: Sony SL-C7 Rebuild

Hi All, Used to service a lot of SL-C7's at Telefusion and the JVC HR-7700's also at Telefusion. They rented many makes and models of VCR including Betamax's and VHS's. Like you say the Sony Betamax's gave very good pictures, which is why I bought it. The JVC HR-7700 gave quite poor pictures due to much signal processing unlike the HR-7200's and 7300's which could give very good pictures and record 405 line pictures too.
This arrived today the C7 loader accessory. If I remember rightly it will only go on the later SL-C7's (the ones with the Betamax C7 logo on the front flap) as I think there where slight mechanical changes carried out to accommodate the changer. It will have to go on the second C7 that I have revived when I have a bit of time.
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Old 28th Jun 2015, 11:37 pm   #9
HurtyAC
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Default Re: Sony SL-C7 Rebuild

Hi All, The second SL-C7UB rebuild has been finished. Again the PSU capacitors, timer switches and Ni-Cad battery board rebuild. Two new belts and a good clean up with back tension arm re-lubrication. As this is a later build machine I decided to try and fit the AG-7UB BetaStack multi cassette loader. When fitted this device would not drop the next cassettes down into the VTR. On dismantling it was found that both drop arms had split from their metal collars. These require quite a bit of dismantling to get to. See picture with arrow pointing to one of the arms, there is one on each side on the same shaft. These were repaired with copper wire and a touch of supper glue. All now working. This item requires an additional external PSU and plugging into the VTR's multi-pin camera socket. If you have not seen one of these in operation its on my facebook page. Enjoy the pictures.
Hurty
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