JVC HR-D470U Tracking problems fixed

[redk9258]

Long time listener, first time poster.

So, I have a JVC HR-D470U (sideways loader) that I bought new in 1987. I've used this machine a LOT. I've never done much to it other than clean the tape path, belts and change the super cap (probably in the 90's). Several years ago I was going to watch a tape. It started mistracking and was getting sort of a pulsing on the screen. Eventually it would play OK. I backed the tape up and the part that would not track was OK. I think at that point, I cleaned the transport. It didn't solve the issue. It only got worse and happened with all tapes. Later, I tried new belts and idler tire. Still didn't resolve it. I just put it away and bought another VCR that worked. I decided to try to get this going a couple of times over the last several years but just got frustrated. I'm not a trained technician. I took electronics in high school. So I'm more of a tinkerer. I decided to try get it going again recently. Judging by the symptoms of not tracking, and studying the service manual, I decided that the control pulse is not being read properly. Another symptom was that it could not automatically select the tape speed. So I studied the schematic and thought hey this cap seems like a likely culprit. I swapped it out and nope wasn't the problem. I did notice that if I would just let it play a tape eventually it would start tracking OK for a while then act up again. I was watching a guy on YouTube diagnose something. He used heat to find bad caps. I thought hey why not try heat! I got a hair dryer out and heated the circuit board near that cap I replaced. BINGO! Within seconds, it straightened out for a while and then acted up again. More heat and bam, plays fine. I eventually narrowed it down to a 47µF capacitor (C23). I pulled it out and tested it on my Mega 328 component tester. It read 1400pF at first. Then it read 18µF with 140 Ohms ESR! I put a new cap in and now it is working pretty good. I can even play a tape that was recorded in EP in 1987! Even HiFi is working good. I need to replace the super cap again because it loses it's time as soon as it is unplugged. I also need to check the lubrication and belts, It is having when I first hit play. Either the belt is slipping or the lube is dried up (I think) and is having trouble at the last bit of movement. I have a new super cap on the way from DigiKey, so I'll look at it then.

Anyway, I just wanted to post this here in case someone else has a similar problem like me.

[redk9258]

PS. The PCB must have had a production error or revision. The cap I changed was not mounted in both holes of the designated place on the PCB. One leg ran over to a pin on an IC and was soldered there. The schematic shows it connected like that. That's the way it came from the factory.

[Electronic M]

JVC made a few Zenith badged versions of those sideways loaders. I own a Zenith (that works) and a JVC I've yet to try(previous owner said it had problems).
My Zenith side loader had an issue where hifi audio and video were perfect but every ~11sec both would drop out my problem was one of the main filter lytics near the power transformer.
Seems like caps are getting lousy in these decks. Probably in another decade or two these will need full recaps to work well.
Good detective work you did.