There was a tape stuck in it because the entire VCR appeared to be
dead, so I disconnected the loading motor and applied my own power to
eject it. No problems there. Now I was able to disassemble the thing.


The SMPS seems to be at the correct voltages printed on the PCB. I got
the carriage to lower as if a tape was being inserted. Sometimes the
display works, sometimes not. The VFD filament voltage is present.
The loading motor and reel motor just moves in little bursts every 0.5
second or so, then occasionally both run for about 1 second straight.
Then it goes back to short bursts. If I unplug it, it continues with
the erratic motor motion. The entire display will sometimes blink
along with the motor motion.

However, there is a 5.8V supply that drops by about 1 volt (very short
drop, a few milliseconds) every time the motors move. The odd thing
is, this periodic voltage sag still occurs even when the VCR appears to
be completely dead.

This VCR was working one hour, then quit working. No electrical storms
or anything unusual. Only I had access to it. I'm familiar with
electronics, but not a VCR expert. Any suggestions?

Check for high ESR caps in the power supply. You will need an ESR meter to
do so.

--

JANA
_____


wrote in message
oups.com...
There was a tape stuck in it because the entire VCR appeared to be
dead, so I disconnected the loading motor and applied my own power to
eject it. No problems there. Now I was able to disassemble the thing.


The SMPS seems to be at the correct voltages printed on the PCB. I got
the carriage to lower as if a tape was being inserted. Sometimes the
display works, sometimes not. The VFD filament voltage is present.
The loading motor and reel motor just moves in little bursts every 0.5
second or so, then occasionally both run for about 1 second straight.
Then it goes back to short bursts. If I unplug it, it continues with
the erratic motor motion. The entire display will sometimes blink
along with the motor motion.

However, there is a 5.8V supply that drops by about 1 volt (very short
drop, a few milliseconds) every time the motors move. The odd thing
is, this periodic voltage sag still occurs even when the VCR appears to
be completely dead.

This VCR was working one hour, then quit working. No electrical storms
or anything unusual. Only I had access to it. I'm familiar with
electronics, but not a VCR expert. Any suggestions?

JANA wrote:
Check for high ESR caps in the power supply. You will need an ESR meter to
do so.

--

JANA
_____

I found the problem. I had a feeling it was power supply caps too.
But it wasn't one of the output filter caps, it was a 22uF
non-polarized cap on the primary side of the switching xformer. It
measures 0.1uF with my LC53 Z meter.

Sucks it's a non-polar; out of the hundreds of caps in my stock, I have
none of these type.

These were Samsung - built and they also made lots of models for RCA, (RCA
VR506, Samsung VR3701, etc).

There's an RCA part number for this cap - it's fairly cheap, if it's
available that is.

I'll try to look it up and repost.

Also, one could probably get it from bdent.com

Mark Z.

wrote:
JANA wrote:
Check for high ESR caps in the power supply. You will need an ESR
meter to do so.

--

JANA
_____

I found the problem. I had a feeling it was power supply caps too.
But it wasn't one of the output filter caps, it was a 22uF
non-polarized cap on the primary side of the switching xformer. It
measures 0.1uF with my LC53 Z meter.

Sucks it's a non-polar; out of the hundreds of caps in my stock, I
have none of these type.

wrote:
JANA wrote:
Check for high ESR caps in the power supply. You will need an ESR
meter to do so.

--

JANA
_____

I found the problem. I had a feeling it was power supply caps too.
But it wasn't one of the output filter caps, it was a 22uF
non-polarized cap on the primary side of the switching xformer. It
measures 0.1uF with my LC53 Z meter.

Sucks it's a non-polar; out of the hundreds of caps in my stock, I
have none of these type.

RCA number 194339. There's normally 2 caps in there, just pitch the smaller
one or throw it in the old parts drawer...

Mark Z.

Sucks it's a non-polar; out of the hundreds of caps in my stock, I have
none of these type.

Use two 47 uF connected in series back to back ( positives shorted,
negatives soldered in circuit)?.

jango2 wrote:
Sucks it's a non-polar; out of the hundreds of caps in my stock, I
have none of these type.

Use two 47 uF connected in series back to back ( positives shorted,
negatives soldered in circuit)?.

BTW 22uF isn't critical, these units work up until the cap is almost open.
I'm sure a 10uF would work fine.

mz

Mark D. Zacharias wrote:
These were Samsung - built and they also made lots of models for RCA, (RCA
VR506, Samsung VR3701, etc).

There's an RCA part number for this cap - it's fairly cheap, if it's
available that is.

I'll try to look it up and repost.

Also, one could probably get it from bdent.com

Mark Z.


I'm not going to bother getting the "exact replacement"; I'm just going
to get a generic non-polarized cap. But what I'm wondering is, how
robust is hooking two regular electrolytics together, + to + to make a
non-polar cap?

wrote in
ups.com:


Mark D. Zacharias wrote:
These were Samsung - built and they also made lots of models for RCA,
(RCA VR506, Samsung VR3701, etc).

There's an RCA part number for this cap - it's fairly cheap, if it's
available that is.

I'll try to look it up and repost.

Also, one could probably get it from bdent.com

Mark Z.


I'm not going to bother getting the "exact replacement"; I'm just going
to get a generic non-polarized cap. But what I'm wondering is, how
robust is hooking two regular electrolytics together, + to + to make a
non-polar cap?

Fairly robust PROVIDED you use diodes [properly rated to handle the
currents and voltages] across each cap to prevent back biasing it during
the other cycle.





--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap