I've had this Sony CCD-FX620 since it was new in 1994. A while back I
replaced the smd caps on the audio/video board and it restored the poor
picture and audio back to normal. I powered it up a few days ago, ejected
the tape that was in it, and inserted a brand new one. Then it went dead. I
tried a different battery and still nothing. Upon disassembly, I noticed
that one of the two 1.6 amp fuses, F951, in the power supply was open. I
mulled over the situation, replaced the fuse, and powered it up again but
this time with my bench power supply hooked up to the battery terminals. My
bench supply can be set to shut down at a predetermined current threshold. I
set it for about 1.8 amps and it powered up again no problem. I then tested
my battery to see if it wasn't holding a charge. It's a Sunpak 3000mAh
RB-90. I used the charger that came with the camcorder which is an AC-V25A
to charge this battery. I was quite surprised to see that my meter displayed
a reading of 8.18 volts. It's supposed to be a 6 volt battery. The schematic
indicates the battery input as the 6.5V unregulated supply. Despite this
finding, I hooked up the battery again to the camcorder and the same fuse
immediately blew. I've not come across this type of situation in the past
where a battery would charge to a voltage so high, that it would take out a
fuse in a portable device. I suppose there could be something wrong in the
camcorder which cannot tolerate an 8 volt input. I've had this battery for a
while and never had this problem before. I tried to disassemble the charger
but there is something preventing me from opening it without an extreme
amount of force. I don't want to use a crow bar on it just yet.

I'm anxious to hear the s.e.r. wisdom as to what could be causing the high
battery voltage or the camera's quick blowing of fuses.

Thanks for your reply.
--
David Farber
David Farber's Service Center
L.A., CA

I don't know your camera unit to advise you on what to check.

I can tell you that the battery charger with no load has to put out a
higher voltage than the chargeable battery is rated at. There is usually
about a 20% overhead. The charger is current regulated to the proper
amount for the battery specs. It works with the principal where the
battery regulates the charge voltage. The charger regulates charge
current.

In an automobile, if the battery was disconnected, which I would not do
while the engine is running, the open end voltage would read about 16 to
18 Volts. If you leave the car stopped over night and come in the
morning. the battery would most likely read about 12.5 Volts. When you
start the car, the batter voltage should go up to about 13.5 to about
14.7 Volts. It nominal should be about 13.8 Volts.

As chargeable batteries age, they tend to not be able to hold their
charge as long. After some time the battery may start to go shorted or
opened a little. If the battery is opened, the voltage across it will be
very high in comparison to what it is supposed to be. If the battery is
shorted or has internal leakage, the voltage will read lower than
normal. In both types of defects the battery will not be very useful.
Normally, as chargeable batteries age, they lose their ability to hold
their charge. They discharge more quickly under load.

For example, if a battery is rated at 12.5 Volts, the charger may put
out 14.5 to 16.8 Volts for charging. When the battery is released from
the charger, it may read about 13.6 to 13.9 Volts with no load.

To measure the charge current from a simple DC output charger, the
process can be a bit involved, but it is simpler that from a charger
that uses DC pulse drive, and varies the duty cycle to control the
charge current.

With a DC charger, you can put an amp meter in series with a known good
battery that is discharged. You can take an Ampere reading and see what
the actual discharged battery charging current is. As the battery is
charging up, the current should decrease. Eventually, when the battery
is fully charged, you should be able to see the sustaining charging
current.

For a pulse drive charger, you would need a scope with a current probe.
The procedure is the same, but you will be reading the peak current. To
have the RMS current, this would be complicated since the pulse drive is
not an AC sinewave. A good digital scope should have the option of
having an RMS translation to the screen.

With many of the battery chargers for industrial and consumer camera
products, they also use current and voltage sensing for the battery
condition. These chargers are fairly sophisticated. If the battery gets
too hot during the charging cycle, the charger will lower the charging
current. If the temperature is too hot according to specs, the charger
will stop charging the battery and indicate an error. If the battery
demands too high a charge current, or it is not charging properly, the
charger will shut down.



--

Jerry G.


"David Farber" wrote in message
...
I've had this Sony CCD-FX620 since it was new in 1994. A while back I
replaced the smd caps on the audio/video board and it restored the poor
picture and audio back to normal. I powered it up a few days ago,
ejected
the tape that was in it, and inserted a brand new one. Then it went
dead. I
tried a different battery and still nothing. Upon disassembly, I noticed
that one of the two 1.6 amp fuses, F951, in the power supply was open. I
mulled over the situation, replaced the fuse, and powered it up again
but
this time with my bench power supply hooked up to the battery terminals.
My
bench supply can be set to shut down at a predetermined current
threshold. I
set it for about 1.8 amps and it powered up again no problem. I then
tested
my battery to see if it wasn't holding a charge. It's a Sunpak 3000mAh
RB-90. I used the charger that came with the camcorder which is an
AC-V25A
to charge this battery. I was quite surprised to see that my meter
displayed
a reading of 8.18 volts. It's supposed to be a 6 volt battery. The
schematic
indicates the battery input as the 6.5V unregulated supply. Despite
this
finding, I hooked up the battery again to the camcorder and the same
fuse
immediately blew. I've not come across this type of situation in the
past
where a battery would charge to a voltage so high, that it would take
out a
fuse in a portable device. I suppose there could be something wrong in
the
camcorder which cannot tolerate an 8 volt input. I've had this battery
for a
while and never had this problem before. I tried to disassemble the
charger
but there is something preventing me from opening it without an extreme
amount of force. I don't want to use a crow bar on it just yet.

I'm anxious to hear the s.e.r. wisdom as to what could be causing the
high
battery voltage or the camera's quick blowing of fuses.

Thanks for your reply.
--
David Farber
David Farber's Service Center
L.A., CA

"David Farber" wrote in message
...
I've had this Sony CCD-FX620 since it was new in 1994. A while back I
replaced the smd caps on the audio/video board and it restored the poor
picture and audio back to normal. I powered it up a few days ago,
ejected
the tape that was in it, and inserted a brand new one. Then it went
dead. I
tried a different battery and still nothing. Upon disassembly, I noticed
that one of the two 1.6 amp fuses, F951, in the power supply was open. I
mulled over the situation, replaced the fuse, and powered it up again
but
this time with my bench power supply hooked up to the battery terminals.
My
bench supply can be set to shut down at a predetermined current
threshold. I
set it for about 1.8 amps and it powered up again no problem. I then
tested
my battery to see if it wasn't holding a charge. It's a Sunpak 3000mAh
RB-90. I used the charger that came with the camcorder which is an
AC-V25A
to charge this battery. I was quite surprised to see that my meter
displayed
a reading of 8.18 volts. It's supposed to be a 6 volt battery. The
schematic
indicates the battery input as the 6.5V unregulated supply. Despite
this
finding, I hooked up the battery again to the camcorder and the same
fuse
immediately blew. I've not come across this type of situation in the
past
where a battery would charge to a voltage so high, that it would take
out a
fuse in a portable device. I suppose there could be something wrong in
the
camcorder which cannot tolerate an 8 volt input. I've had this battery
for a
while and never had this problem before. I tried to disassemble the
charger
but there is something preventing me from opening it without an extreme
amount of force. I don't want to use a crow bar on it just yet.

I'm anxious to hear the s.e.r. wisdom as to what could be causing the
high
battery voltage or the camera's quick blowing of fuses.

Thanks for your reply.
--
David Farber
David Farber's Service Center
L.A., CA




"Jerry G." wrote in message
news:fKudnd4j-OQyL5bVnZ2dnUVZ_obinZ2d@uniservecommunications...
I don't know your camera unit to advise you on what to check.

I can tell you that the battery charger with no load has to put out a
higher voltage than the chargeable battery is rated at. There is usually
about a 20% overhead. The charger is current regulated to the proper
amount for the battery specs. It works with the principal where the
battery regulates the charge voltage. The charger regulates charge
current.

In an automobile, if the battery was disconnected, which I would not do
while the engine is running, the open end voltage would read about 16 to
18 Volts. If you leave the car stopped over night and come in the
morning. the battery would most likely read about 12.5 Volts. When you
start the car, the batter voltage should go up to about 13.5 to about
14.7 Volts. It nominal should be about 13.8 Volts.

As chargeable batteries age, they tend to not be able to hold their
charge as long. After some time the battery may start to go shorted or
opened a little. If the battery is opened, the voltage across it will be
very high in comparison to what it is supposed to be. If the battery is
shorted or has internal leakage, the voltage will read lower than
normal. In both types of defects the battery will not be very useful.
Normally, as chargeable batteries age, they lose their ability to hold
their charge. They discharge more quickly under load.

For example, if a battery is rated at 12.5 Volts, the charger may put
out 14.5 to 16.8 Volts for charging. When the battery is released from
the charger, it may read about 13.6 to 13.9 Volts with no load.

To measure the charge current from a simple DC output charger, the
process can be a bit involved, but it is simpler that from a charger
that uses DC pulse drive, and varies the duty cycle to control the
charge current.

With a DC charger, you can put an amp meter in series with a known good
battery that is discharged. You can take an Ampere reading and see what
the actual discharged battery charging current is. As the battery is
charging up, the current should decrease. Eventually, when the battery
is fully charged, you should be able to see the sustaining charging
current.

For a pulse drive charger, you would need a scope with a current probe.
The procedure is the same, but you will be reading the peak current. To
have the RMS current, this would be complicated since the pulse drive is
not an AC sinewave. A good digital scope should have the option of
having an RMS translation to the screen.

With many of the battery chargers for industrial and consumer camera
products, they also use current and voltage sensing for the battery
condition. These chargers are fairly sophisticated. If the battery gets
too hot during the charging cycle, the charger will lower the charging
current. If the temperature is too hot according to specs, the charger
will stop charging the battery and indicate an error. If the battery
demands too high a charge current, or it is not charging properly, the
charger will shut down.



--

Jerry G.



Hi Jerry,

I called the manufacturer of the battery, Tocad America Inc., and talked to
an engineer. By the way, this a nickel cadmium battery. We agreed that the
battery was exhibiting some very strange properties. We also agreed that
even if the charger was defective, it could not increase the battery voltage
past its normal fully charged state. So I'm sending off my battery directly
to the engineer I spoke with this morning and hopefully he can figure this
out.

Thanks for your reply.
--
David Farber
David Farber's Service Center
L.A., CA

We also agreed that even if the charger was defective, it
could not increase the battery voltage past its normal fully
charged state.

I'm not so sure. I'd drop the charger in the box with the battery. Never
"assume".

"William Sommerwerck" wrote in message
. ..
We also agreed that even if the charger was defective, it
could not increase the battery voltage past its normal fully
charged state.

I'm not so sure. I'd drop the charger in the box with the battery. Never
"assume".



I read the small print on the charger. It says, "DC out, 7.5V 1.5A(VTR) 10V
1.1A(BATT)" So maybe it isn't a surprise that the charger is able to charge
the battery to 8 volts or higher.

I haven't sent the battery in just yet. I'm still not convinced the
camcorder is working properly. There are times I will power it up with a
6.5V supply voltage and moments later, the overload light comes on my power
supply. 6.5 volts is what the schematic indicates as the battery input
voltage. This is a full volt lower than the 7.5 volts that the
charger/supply outputs (the charger can also power the camcorder when the
power switch is moved to DC out). I've set the current limiting of the power
supply to 1.6 amps, the value of the fuse, even though there are other
branch circuits that don't go through this same fuse. The rated power stated
in the camcorder service manual is 6 watts. At the moment, I have my bench
supply set at 7.75 volts and the current protection at 1.6 amps which would
provide over 12 watts of power. The current reading is steady and shows,
550ma, and it is not shutting down. I've also noticed that the power supply
will sometimes shut down when the camcorder is in the "off" mode if I crank
up the voltage somewhere in the high 7 volt range. There is never any slow
increase of current. It just jumps from 550ma to a shut down situation.

Thanks for your reply.
--
David Farber
David Farber's Service Center
L.A., CA