More JVC HR-D470U goodness and lesson learned...

[redk9258]

In the last couple of days, I have fixed 2 more broken JVC HR-D470U VCRs. Both had similar problems. They would thread the tape and it played but at the wrong speed and no real picture. After finding a bad cap in my original HR-D470U in the servo section, I was looking at the same caps and not getting anywhere. I was trying to read the sync pulse from the control head circuit. I couldn't get it so I knew something was wrong and I was thinking the head could be bad at this point. I cleaned it several times and no pulse on the scope while connected to the test point. It did read a couple of hundred Ohms so that was promising. For some reason I decided to put my scope on the power supply. Holy crap, the ripple was horrible on the 5V supply. I pulled the power supply and found 2 caps completely open with my Blue ESR meter. I think I am starting to love this thing! One of the caps was a 3300MF @ 16V. When I unsoldered it, one leg was corroded off! I recapped the power supply and now it's back to life. The VFD display is brighter now too. It works very well with one exception. The tracking knob has no effect. I have another 470U with the same problem.

I then looked at another 470U that had a similar speed / tracking problem. I immediately went to the power supply this time. Ripple was horrible on this one too! I checked the caps with my ESR meter and the 3300MF 16V cap was open. I unsoldered it and top my surprise the leg was corroded off like the other one! I only replaced that cap at this time. I put it back together and I had lines across the picture that tracking would not take out. I put my scope on the test point to check the FM envelope. It didn't look right. I was looking at the mechanism and exit side post (P3, I think) was loose! I turned it and right away the picture and HiFi sound came back to life! I used the scope and set the adjustment as close as I could using a couple of tapes, both factory recorded and ones I recorded. I have it playing a tape that was recorded in EP on Thanksgiving Day 1989.. almost 35 years ago! I recorded the radio on the HiFi tracks and whatever was on TV (Dirty Dancing). It's tracking fine and sounds great!

What I have learned is to check the power supply first before looking into anything else! If anyone is having any trouble with their HR-D470U, you might want to check the power supply caps- especially that 3300MF @ 16V. It's a Mashusita cap, BTW.