JVC HR-J470 video problem

[Tournifreak]

Hi, I'm hoping some kind soul can help...

My video recorder has been in a cupboard for the last couple of days
whilst decorating. Just plugged it in again and it's not working
properly.

Audio is fine. Video looks as though the tracking is way, way off.
i.e. no discernable picture, but not "snowy", or blank. There's a
white band across the bottom of the screen that moves up and down a
bit.

I've tried via SCART and through the modulator - same on both.

Any ideas anyone? If it's something relatively straightforward, I'll
give it a go. I'm an electronic engineer, so quite happy soldering SMT
components etc. I also have basic test equipment. I just don't have a
clue where to start!

I suppose it could have been "bashed" during the move.

Thanks in advance for any help!

Jon.

 

[Sofie]

Jon:
The very FIRST thing that should be done is a thorough professional
cleaning..... no cleaning tapes please.
If a proper cleaning doesn't solve the problem then the next place to focus
attention on would be the roller guides to verify that they are fully
seating in the v-blocks when the tape is loaded around the drum. Also
check the roller guide brass press-in pins that hold the roller guides in
the rails and the plastic pins that connect to the roller guide positioning
lever arms..... verify that they are all fully seated.
If all of the above checks out OK and the problem still persists then you
should check and/or replace the 3.3uf smd electrolytic on the drum motor
board on the bottom side of the deck.
Finally, if there is still a problem then more than likely the upper
drum/video heads are faulty or worn out. Hook up your oscilloscope on the
video head preamp..... modulated RF output.... to video to verify this....
look for a symmetrical RF envelope. also check for drum servo lock
If you are still not certain how to properly proceed then you should TAKE
your VCR to a repair shop for at the very least a repair cost estimate so
you can make an intelligent repair decision with facts instead of internet
or telephone guesses.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


"Tournifreak" <wendyjon@ntlworld.com> wrote in message
news:a8d45d8b.0312190910.3b9bd19a@posting.google.com...

Hi, I'm hoping some kind soul can help...

My video recorder has been in a cupboard for the last couple of days
whilst decorating. Just plugged it in again and it's not working
properly.

Audio is fine. Video looks as though the tracking is way, way off.
i.e. no discernable picture, but not "snowy", or blank. There's a
white band across the bottom of the screen that moves up and down a
bit.

I've tried via SCART and through the modulator - same on both.

Any ideas anyone? If it's something relatively straightforward, I'll
give it a go. I'm an electronic engineer, so quite happy soldering SMT
components etc. I also have basic test equipment. I just don't have a
clue where to start!

I suppose it could have been "bashed" during the move.

Thanks in advance for any help!

Jon.

 

[Tournifreak]

"Sofie" <sofie@olypen.com> wrote in message news:<vu6qm3hdidpjd0@corp.supernews.com>...

Jon:
The very FIRST thing that should be done is a thorough professional
cleaning..... no cleaning tapes please.
If a proper cleaning doesn't solve the problem then the next place to focus
attention on would be the roller guides to verify that they are fully
seating in the v-blocks when the tape is loaded around the drum. Also
check the roller guide brass press-in pins that hold the roller guides in
the rails and the plastic pins that connect to the roller guide positioning
lever arms..... verify that they are all fully seated.
If all of the above checks out OK and the problem still persists then you
should check and/or replace the 3.3uf smd electrolytic on the drum motor
board on the bottom side of the deck.
Finally, if there is still a problem then more than likely the upper
drum/video heads are faulty or worn out. Hook up your oscilloscope on the
video head preamp..... modulated RF output.... to video to verify this....
look for a symmetrical RF envelope. also check for drum servo lock
If you are still not certain how to properly proceed then you should TAKE
your VCR to a repair shop for at the very least a repair cost estimate so
you can make an intelligent repair decision with facts instead of internet
or telephone guesses.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Daniel,
Thanks for the help. Problem turned out to be an electrical problem
with the heads. Dry joint on the flexible PCB. Working perfectly now.
Thanks again.
Jon.