JVC VF-V7E viewfinder - squeals, no display

[Philip Pemberton]

Hi,
I've got a JVC VF-V7E viewfinder that sounds like it's generating EHT, but
the tube isn't displaying a picture. This is the same fault "Andre" described
in his message (subj: Odd camcorder viewfinder fault). Symptoms are:
Viewfinder is emitting a squealing noise
No picture on VF. tube
The viewfinder's HT contact was absolutely filthy - it was covered in a thick
coating of what appeared to be black carbon. This has been scraped off and
the contact has been cleaned with 70% IPA. This has produced no change in its
behaviour. The viewfinder did originally work - I left it hooked up to an
8VDC power supply and a Playstation running a demo CD (don't laugh -
Playstations make reasonably good test pattern generators). After
approximately ten minutes, the 'finder died, never to power up again.
Can anyone offer a suggestion as to what I should do to the viewfinder now?
I've got another JVC viewfinder, a VF-V45E, that seems to use very similar
circuitry, the same tube and a different casing. This viewfinder uses the
same connector (an 8-pin round connector that bears the logo "HRS") and
operates fine.

Thanks.
--
Phil. | Acorn RiscPC600 Mk3, SA202, 64MB, 6GB,
philpem@despammed.com (valid address)| ViewFinder, Ethernet (Acorn AEH62),
http://www.philpem.dsl.pipex.com/ | 8xCD, framegrabber, Teletext
.... High voltage can give a dangerously uncomfortable discharge.

 

[Philip Pemberton]

In message <0jN_a.255974$R92.255703@news2.central.cox.net>
"Patch" <bob_acord@hotmail.com> wrote:

Usually when they squeal like that it's caused by bad electrolytic caps.
If you have an ESR meter you might check them. If not, just replace them
all. Some of them have a small metal box inside that has 3 or 4 caps in it.
Yay. Bad electrolytics. Most of the electros in the 'finder seem to be normal

through hole types, no SMDs. The date code on the plastic casing was 6-1986
believe it or not.
Has anyone here had trouble with the blue "EXPO" branded caps? This thing's
full of 'em.

Later.
--
Phil. | Acorn RiscPC600 Mk3, SA202, 64MB, 6GB,
philpem@despammed.com (valid address)| ViewFinder, Ethernet (Acorn AEH62),
http://www.philpem.dsl.pipex.com/ | 8xCD, framegrabber, Teletext
.... Reactance: your imaginary friend.

 

[Dave D]

"Philip Pemberton" <philpem@despammed.com> wrote in message
news:0735ee214c.philpem@dsl.pipex.com...

In message <0jN_a.255974$R92.255703@news2.central.cox.net
"Patch" <bob_acord@hotmail.com> wrote:

Usually when they squeal like that it's caused by bad electrolytic caps.
If you have an ESR meter you might check them. If not, just replace them
all. Some of them have a small metal box inside that has 3 or 4 caps in
it.
Yay. Bad electrolytics. Most of the electros in the 'finder seem to be
normal
through hole types, no SMDs. The date code on the plastic casing was
6-1986
believe it or not.
Has anyone here had trouble with the blue "EXPO" branded caps? This
thing's
full of 'em.

Later.
--

Electrolytic caps *are* bad news, their whole purpose in life is to annoy
techies ;-)

Dave