[TechAssist] Re: JVC VCR HR-J420U acts like bad heads- but is it?
- From: Gary McCartney <gary@xxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Thu, 08 May 2003 11:57:29 -0400
Tony, I can't seem to find this 3.3 uF cap. The drum motor board is
mounted on top of the drum and there are only a few brown surface mount
chip caps but no surface mount electrolytics. Checked the solder side of
the main board and didn't see any surface mounts there either.
Thanks
Gary McCartney
McCartney Electronics
7134 Fife Rd, RR 7
Guelph Ontario Canada N1H 6J4
Fax: (519)821-1530
email: gary (at) number63.ca
Tonys TV wrote:
>
> Hi Gary:
> I'm not exact about this model,some jvc have problem with drum
> motor,actually is the capacitor that mounted on the circuit board (3.3uf
> capacitor),try changing it,it may fix your problem.HIH
> Tony @ Tony's tv in Victoria B.C.
> From: "Gary McCartney" <gary@xxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Thursday, May 08, 2003 7:13 AM
> Subject: [TechAssist] JVC VCR HR-J420U acts like bad heads- but is it?
>
> >
> > I have this JVC VCR model HR-J420U which shows a few lines across the
> > screen near the top during playback of some SP or EP speed tapes.
> >
> > Pulling the back tension post out further by hand would make the lines
> > go away but adjusting the arms position with it's set screw would only
> > result in a worse picture, never better.
> >
> > I scoped the RF envelope waveform and it didn't look very good, not
> > square at all. I set the tracking to manual and tried to align guide
> > posts so the envelope would be squared up. This seemed to work out ok
> > using my test alignment tape, but some other factory made tapes still
> > had the problem and some were even worse than before I made any
> > adjustments. Actually the envelope waveform is now fluctuating. It won't
> > stay the same shape while playing most tapes. It keeps gradually losing
> > the signal from the one head and getting it back again slowly, while the
> > other head goes from square waveform shape to oval shape. Hope I've
> > explained this ok. The control pulse appears to be stable at approx. 3V
> > p-p at C.P. test point, regardless of what tape I am playing.
> >
> > I removed the upper drum and checked for green corrosion at the base of
> > the post as was a problem with some JVC machines a few years ago. All
> > was clear. I also tried a new spring at the back tension arm but that
> > didn't help either. This problem seems to be worse on EP speed tapes.
> > Are my heads just too weak to lock in the RF signal or are there other
> > known conditions with these machines causing this type of fault?
> >
> > Thanks for any help.
> > --
> >
> >
> >
> >
> > Gary McCartney
> >
> > McCartney Electronics
> > 7134 Fife Rd, RR 7
> > Guelph Ontario Canada N1H 6J4
> > Fax: (519)821-1530
> > email: gary (at) number63.ca
> >
> >
> ****************************************************************************
> *
> > The Tech Address Book:
> > http://www.tech-assist.org/secure/tip/contact.html
> > Add a Repair Tip Here, or Change/Remove your Email Address:
> > http://www.tech-assist.org/secure/tip/main.html
> > Lost Password:
> > http://www.tech-assist.org and select "Lost your Login Info?".
> > Email Archives:
> > //www.freelists.org/archives/techassist/
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.476 / Virus Database: 273 - Release Date: 4/24/2003
>
> *****************************************************************************
> The Tech Address Book:
> http://www.tech-assist.org/secure/tip/contact.html
> Add a Repair Tip Here, or Change/Remove your Email Address:
> http://www.tech-assist.org/secure/tip/main.html
> Lost Password:
> http://www.tech-assist.org and select "Lost your Login Info?".
> Email Archives:
> //www.freelists.org/archives/techassist/
--
*****************************************************************************
The Tech Address Book:
http://www.tech-assist.org/secure/tip/contact.html
Add a Repair Tip Here, or Change/Remove your Email Address:
http://www.tech-assist.org/secure/tip/main.html
Lost Password:
http://www.tech-assist.org and select "Lost your Login Info?".
Email Archives:
//www.freelists.org/archives/techassist/
Other related posts:
