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Old July 10th, 2019, 11:04 AM   #1
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Jvc gy-hd*** camera family re-attaching blue sensor.

If one was to design and build an alternative attachment system for the many detached blue-channel sensors out there, would there be anyone interested I wonder in having theirs done, given the cameras are quite dated nowadays and their comparatively low value on eBay.

The camera will operate with the right side panel off and just by hand manipulating the detached sensor PCB after first attaching it roughly by the threaded jig end to thin cardboard, one can get pretty close to a good image. One has to be very careful to avoid the conductors on the PCB shorting across the the green channel PCB. This time, I dodged a bullet before I thought to put an insulating strip in there but permanent damage could be caused.

It might be possible to reattach the sensor with adhesive to the outside onto the black-painted portion of the prism but I suspect the new mount system may have to be by the jig strip as larger glue bonds may shrink and pull the sensor off alignment.

A large monitor screen would be needed for final trim to get rid of blue edges.

Last edited by Bob Hart; July 10th, 2019 at 11:08 AM. Reason: error
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Old July 10th, 2019, 12:15 PM   #2
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Re: Jvc gy-hd*** camera family re-attaching blue sensor.

Footnote:

There was a little white indicator arrow popped up on the LCD screen which I had not ever seen previously and suggested which direction the sensor was not in vertical alignment. One time I got it very close, the image seemed to come in by itself and the arrow extinguished. I cannot find anything in the service manual about it.

I wonder if these things automatically track the images across the sensor to align the colour channels so long as the sensors are aligned within a certain tolerance. It would be clever stuff for the times the camera was made. Apparently there was also an automatic function evolved for adjusting the split screen effect which aggravated the early adopters of the cameras.

If there are any retired JVC camera techs out there, I would be interested in your responses.
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Old July 11th, 2019, 01:03 PM   #3
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Re: Jvc gy-hd*** camera family re-attaching blue sensor.

For the curious among readers, from appearances, it sees that the sensors are attached by temporary mounting strips and wedge ends to an assembly jig. There are eight holes altogether some threaded, two elongated as if to allow the mounting strips to slide for horizontal alignment and skew slightly for roll adjustment.

These appear to be there for assembly of the PCBs to the actual sensors as the holes are inaccessable due to the PCBs being in the way. I am beginning to suspect that the sensors are as accurately aligned to the PCBs as possible in fine jigs so that as little adjustment as possible is needed for the final assembly to the prism.

The wedge shapes in each of the temporary mounting strips are possibly there for an accurate clamping scheme with external adjustments to align the sensors then glue spots being added then the sensors offered up to the prism and clamped there until the glue sets.

A scheme to re-attach a dislodged sensor could be to use three of the screw holes at ends of the mounting strips to support one end of the loose sensor to the attached sensors and the wedge shapes at the opposite ends of them used for support into a home made matching support. The build accuracy would have to be better than five microns - big challenge.

Last edited by Bob Hart; July 11th, 2019 at 01:06 PM. Reason: errors
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Old July 12th, 2019, 10:51 AM   #4
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Re: Jvc gy-hd*** camera family re-attaching blue sensor.

After messing around with a small plate dummied up out of thin cardboard mastered to a good but electronically faulty sensor block and manually adjusting the opposite end of the blue sensor PCB which remained floating, it seems that it may be possible to remount the blue sensor mechanically without adhesive although with adhesive would be a better fix.

Micro-adjustments may be possible by using screws with cone ends or countersunk heads as wedges which is a similar arrangement to the very old Sony EIAJ video head alignment system. The screws would attach through the mechanical mounts to bear against the original jig strip which remains attached to the sensor. I think those do double duty as heat sinks. I have yet to work out a method.

Any ideas from any JVC techs would be welcome.
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Old July 14th, 2019, 10:11 AM   #5
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Re: Jvc gy-hd*** camera family re-attaching blue sensor.

For what it is worth, here is a rather shoddy phone pic of the LCD screen of the image yield with the blue sensor relocated. I used roughcut bridges made from cereal packet cardboard with a razor blade, mastered to another intact sensor block. It was the labour of about 30 minutes with the sensor relocated by fingers alone and no adjustment screw system.

Misalignment remains on the left side of the image with a blue margin on the lower edge and yellow margin on the upper. Obviously much finer adjustment is needed for the defects not to be seen on a large display screen. You will observe in the bottom left of the screen an upwards arrow which indicates the direction the blue sensor needs to move for alignment.

One wonders how much the issue may have been little more than a lack of the will to make it happen on the part of JVC. Common sense suggests that replacement of the defective assembly is the preferred option because there then remains little chance of comeback due to an ineffectively executed repair, an expensive business to do properly when costs of labour and clean rooms are concerned.

A re-attachment regimen would also need special jigs and techs being trained worldwide. Replacement of the entire sensor block probably makes more sense.

The JVC GY-HD*** camera family had its teething problems but the fine miniature execution of everything built inside is sweet to observe. there was a lot of hard design work done. One imagines a bunch of little inscrutable techies with thick-rimmed glasses working slavishly for the corporation. One hopes they derived a certain amount of pleasure and pride in what they built at the time.
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Last edited by Bob Hart; July 14th, 2019 at 10:19 AM. Reason: error
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