Hi there,
I have to repair a VX5500, which has a bad playback-picture.
I replaced the headdrum, picture is far better, but still bad.
The picture has several horizontal noise-bars.
Tape path ist clean and correctly adjusted.
Checking the FM from tape I found packets of RF-oszillations
with a level that is twice the FM level.
Packet lenght ist about 4 milliseconds.

Is there something known for that?

73
Peter

Maybe it's not adjusted correctly after all. Sounds exactly like an
alignment problem.

Mark Z.


"Peter Lehmann" wrote in message
...
Hi there,
I have to repair a VX5500, which has a bad playback-picture.
I replaced the headdrum, picture is far better, but still bad.
The picture has several horizontal noise-bars.
Tape path ist clean and correctly adjusted.
Checking the FM from tape I found packets of RF-oszillations
with a level that is twice the FM level.
Packet lenght ist about 4 milliseconds.

Is there something known for that?

73
Peter

On Mon, 07 Feb 2005 21:39:24 +0100, Peter Lehmann
wrote:

Checking the FM from tape I found packets of RF-oszillations
with a level that is twice the FM level.
Packet lenght ist about 4 milliseconds.

Is there something known for that?

Yup.

It is the capstan motor driver that oscillates. Change 4
electrolyticaps on capstan motor board. Remove motor, and remove
flywheel from motor before attempting to repair!

The old caps can be a pain to remove, lot of heat is necessary. They
can be replaced with leaded versions with short legs.

"Christian P." wrote in message
...
On Mon, 07 Feb 2005 21:39:24 +0100, Peter Lehmann
wrote:

Checking the FM from tape I found packets of RF-oszillations
with a level that is twice the FM level.
Packet lenght ist about 4 milliseconds.

Is there something known for that?

Yup.

It is the capstan motor driver that oscillates. Change 4
electrolyticaps on capstan motor board. Remove motor, and remove
flywheel from motor before attempting to repair!

The old caps can be a pain to remove, lot of heat is necessary. They
can be replaced with leaded versions with short legs.



I've seen bad caps on these too, but this still sounds like alignment issues
to me.

Could be wrong though, wouldn't be the first time....


Mark Z.

Mark D. Zacharias wrote:


Yup.

It is the capstan motor driver that oscillates. Change 4
electrolyticaps on capstan motor board. Remove motor, and remove
flywheel from motor before attempting to repair!

The old caps can be a pain to remove, lot of heat is necessary. They
can be replaced with leaded versions with short legs.




I've seen bad caps on these too, but this still sounds like alignment issues
to me.

Could be wrong though, wouldn't be the first time....


Mark Z.



Hi there,
thank you for your replies.
I think it's not an alignment issue.
The FM from tape is in perfect rectangular shape for both heads.
The oszillations could also be seen on the 5V play-voltage to the
head-amp with an amplitude of 50mVpp. Assuming a problem with the
filter caps for the 5V line in the head-amp, I replaced the electrolytic
in the head-amp without success :-/

73
Peter

On Tue, 08 Feb 2005 16:18:15 +0100, Peter Lehmann
wrote:

: Assuming a problem with the
filter caps for the 5V line in the head-amp, I replaced the electrolytic
in the head-amp without success :-/

Just change the caps on the CAPSTAN MOTOR!

Christian P. wrote:


Just change the caps on the CAPSTAN MOTOR!

Hi Christian,
I changed the caps in the headamp -before- I got your
message. At that time I would never have the idea that the
capstan-motor ist the reason for the oszillations in the headamp's output.
This morning I repaired the capstan-motor.
Success!! :-)
Especially the 22µ/35V caps were leaking, causing corrosion.
And the fishy smell when heated with the iron....

A 50W Weller TCP with standard tip produces sufficient heat to
remove the caps.

73
Peter

On Wed, 09 Feb 2005 15:40:32 +0100, Peter Lehmann
wrote:

This morning I repaired the capstan-motor.
Success!! :-)
Especially the 22µ/35V caps were leaking, causing corrosion.

Yup.
Congratulations ;-)

When your VX starts to have bad pic/sound via tuner, change all caps
in the IF can

When your VX starts to have bad picture in PB change all caps on the
top PCB

When your VX fails to start change all caps in the PSU

When your VX starts to have problem synchronising in PB/REC change all
caps on bottom PCB

Oh - and then tere is alle the mechanical stuff ;-)

Yup.
Congratulations ;-)

When your VX starts to have bad pic/sound via tuner, change all caps
in the IF can

When your VX starts to have bad picture in PB change all caps on the
top PCB

When your VX fails to start change all caps in the PSU

When your VX starts to have problem synchronising in PB/REC change all
caps on bottom PCB

Oh - and then tere is alle the mechanical stuff ;-)


Hi Cristian,
one question ist left.
When switched to stand-by, there is a faint scheme of EE-picture on
the monitor connected to the AV-output.
When switched to stop-mode there ist a light-blue screen.
When I switch the VX on or off, I have a correct picture on the screen
for a short time, about one second. No sound from tuner.
Is this a problem of "how to use your equipment" or another fault?
I'm thinking of the system-integration with other B&O sets.

For more than 10 years I'm repairing VCRs but some of them seems to be
more equal...and this VX ist the first one in all the time...

73
Peter