Nokia VCR3785 showing "sparkles" on tuner-picture

[Marko Taponen]

Hi all,

I was wondering if anyone could give me a hint or piece of info on following
matter.

I have Nokia VCR3785 hifi video's (~6-7 yrs old) and now the tuner picture
is really poor.
I mean when I connect th TV to the SCART- outlet of the VCR the picture is
really poor when looking broadcast and ok when looking cassette.
I'm connected on cable, and my philips TV (which is btw really sensitive for
bad transmission) is showing good picture.

But the VCR-tuner picture shows sparkles. I can change the sparks to
"grooves" by turning a trimmer on top of the RF box but the picture is still
not ok. Also if I lower the amt of signal by partially removing the RF-in
plug from the jack behind the vcr I see normal, snowy picture without these
sparkles.

I already soldered the RF box out as I suspected something was
"oversteering" there but it looks ~ok.

If someone would know service manual for the device or would have good hints
or guesses how to get more info on the problem please help.

Best Regards
// Marko

 

[eddumweer]

Hi Marko,

If oversteering is the problem, you can try with one ore more 2 way
splitters for coax in the rf-input of the vcr. Every splitter gives about
3.5 dBuV loss in signal.

I myself check the rf signal from the cablenetwork or aerial with a
calibrated rf-meter, and depending the rf signal, alignment of the amplifier
or calling the cablecompanie or using attenuators for getting the right
signalstrength.

If the problem is specially of vhf-channels also check the proper grounding
of connectors, cables because vhf-channels are sensitive for bad grounds
(shielding)

Greetings Peter

"Marko Taponen" <marko.taponen@n_o_s_p_a_m.iki.fi> schreef in bericht
newseQQb.480$%w3.93@read3.inet.fi...

Hi all,

I was wondering if anyone could give me a hint or piece of info on
following
matter.

I have Nokia VCR3785 hifi video's (~6-7 yrs old) and now the tuner picture
is really poor.
I mean when I connect th TV to the SCART- outlet of the VCR the picture is
really poor when looking broadcast and ok when looking cassette.
I'm connected on cable, and my philips TV (which is btw really sensitive
for
bad transmission) is showing good picture.

But the VCR-tuner picture shows sparkles. I can change the sparks to
"grooves" by turning a trimmer on top of the RF box but the picture is
still
not ok. Also if I lower the amt of signal by partially removing the RF-in
plug from the jack behind the vcr I see normal, snowy picture without
these
sparkles.

I already soldered the RF box out as I suspected something was
"oversteering" there but it looks ~ok.

If someone would know service manual for the device or would have good
hints
or guesses how to get more info on the problem please help.

Best Regards
// Marko

 

[Vector Viper]

"Marko Taponen" <marko.taponen@n_o_s_p_a_m.iki.fi> wrote in message
newseQQb.480$%w3.93@read3.inet.fi...

Hi all,

I was wondering if anyone could give me a hint or piece of info on
following
matter.

I have Nokia VCR3785 hifi video's (~6-7 yrs old) and now the tuner picture
is really poor.
I mean when I connect th TV to the SCART- outlet of the VCR the picture is
really poor when looking broadcast and ok when looking cassette.
I'm connected on cable, and my philips TV (which is btw really sensitive
for
bad transmission) is showing good picture.

But the VCR-tuner picture shows sparkles. I can change the sparks to
"grooves" by turning a trimmer on top of the RF box but the picture is
still
not ok. Also if I lower the amt of signal by partially removing the RF-in
plug from the jack behind the vcr I see normal, snowy picture without
these
sparkles.

I already soldered the RF box out as I suspected something was
"oversteering" there but it looks ~ok.

If someone would know service manual for the device or would have good
hints
or guesses how to get more info on the problem please help.

I have seen similar pictures on older vcrs here in the US...there is a 1 or
2.2uf
cap in the i.f. strip that filters the rf AGC, if it goes bad, the pix can
be unstable, snow, streak,
pulse, or jump...experiment with briging caps in the i.f. area....

My first guess...

Aaron H.

Best Regards
// Marko

 

[Marko Taponen]

"Vector Viper" <ahowald@w-link.net> wrote in message
news:101c1lsr40jon90@corp.supernews.com...

snip
I have seen similar pictures on older vcrs here in the US...there is a 1
or
2.2uf
cap in the i.f. strip that filters the rf AGC, if it goes bad, the pix can
be unstable, snow, streak,
pulse, or jump...experiment with briging caps in the i.f. area....

My first guess...

Aaron H.

Thanks -- I had some other responses indicating the same and I soldered of
the IF box and replaced all ElCo's inside. This indeed fixed the problem

Cheers,
// Marko