Philips/B6X12A - Power transformer connection (Techniek Radio/TV)

door svetolik, 26.02.2011, 09:28 (5020 dagen geleden)

Does anybody have schematic of connection for the power transformer of this model?
Thanks

Philips/B6X12A - Power transformer connection

door soundman2 @, Wouw, 26.02.2011, 09:33 (5020 dagen geleden) @ svetolik

There is a simplified service manual to be found here : http://www.radiodatabase.nl/toestellen/philips%20buizenradio%20na%20wo2/B6X12A/B6X12A.pdf
Probably it could help solving your problem.

Soundman2

Philips/B6X12A - Power transformer connection

door svetolik, 26.02.2011, 09:55 (5020 dagen geleden) @ svetolik

Thanks Soundman buth it is too simplified.
There is only basic connection for the power traf and I have 18 pins on it!
Is anybody familiar with this model?[image]

Philips/B6X12A - Power transformer connection

door soundman2 @, Wouw, 26.02.2011, 15:09 (5020 dagen geleden) @ svetolik

You'll have to do some investigation.
Two taps ar somewhat placed in a hole (right side of photograph) Those are the connections of a non resettable thermofuse, resistance between zero ohms when ok.
Connected in series with the primary mains windings.
The transformer has two heater windings, easy recognized, due to the thickness of the windings most about 1mm.
Then there is a split HV windings, three tabs should measure a resistance to each other. No other connection is allowed,
The rest are mainswindings,
Supply one of the heaterwindings with 6 to 7 volts AC.
Now you can measure several voltages on the primary of the transformer.
This is the way i would investigate the transformer.

Soundman2

Philips/B6X12A - Power transformer connection

door svetolik, 26.02.2011, 21:30 (5019 dagen geleden) @ soundman2

Two taps ar somewhat placed in a hole (right side of photograph) Those are the connections of a non resettable thermofuse, resistance between zero ohms when ok

There is no beep when checked resistance between these taps, so where is that thermofuse?

I have measured voltage and on the left side is the taps with 6V+ for heating.
On the right side I have measured >200V between black wire tap (Central tap on the secondary winding from the schematic?) and other taps.
All fuses seems to be ok buth radio is dead.
I have other traf with two input taps two output HV taps, one central/ ground tap and 4 taps for heating, so I need to know connections to make it work.
The old traf that is inside was hot and after vibrations there was no voltage and lights. I beliewe it is dead except section for heating voltage.
Also there is a bunch of cables that comes from input voltage switcher and that makes problem.

Philips/B6X12A - Power transformer connection

door Matthias Meijer @, Dordrecht, 26.02.2011, 22:41 (5019 dagen geleden) @ svetolik

Two taps ar somewhat placed in a hole (right side of photograph) Those are the connections of a non resettable thermofuse, resistance between zero ohms when ok

There is no beep when checked resistance between these taps, so where is that thermofuse?

Then that thermo-fuse is broken.
And in that case it is no wonder the radio does not work.
The thermo-fuse is a small brown plastic tab that is stuck between the windings of the transformer.


I have measured voltage and on the left side is the taps with 6V+ for heating.
On the right side I have measured >200V between black wire tap (Central tap on the secondary winding from the schematic?) and other taps.

You mess up primary and secondary I think.

What you measured on the primary side is the case when the fuse is blown. You measure the voltage you apply to the radio from the mains outlet, and since all eyelets on the primary side are in series, you measure the same voltage there when there is no connection to the tab on the other side of the broken fuse.

All fuses seems to be ok buth radio is dead.

From what I understand from your explanation, the fuse is broken. But there must be a reason why the fuse is blown, so please take care when you proceed.

I have rotated the image 180 degrees to avoid neck-problems when viewing :-)

[image]

And added the part of the B6X12A schematic which shows the primary and secondary windings.

[image]

Please note that my annotations are based on the A3 136 56.2 type number. Which is probably only different from the way the eyelets for the fuse are mounted on the face plate. I guess you have a radio that was specifically designed for sale outside the Netherlands/Belgium.

But as Henk already suggests, you can figure it out by looking at the wires that arrive at the eyelets and by measuring.

It seems that your transformer has both filament windings connected in parallel, and that these are probably connected to ground elsewhere in the radio. The center tap of the high voltage winding and screen (the screen is not indicated in the schematics) are also probably connected to ground somewhere else in the radio. The 'normal' case with all radios that I have seen is that the four lower eyelets on the secondary side are all connected together and to the chassis (ground).

I have other traf with two input taps two output HV taps, one central/ ground tap and 4 taps for heating, so I need to know connections to make it work.

Is that the exact SAME transformer?

The old traf that is inside was hot and after vibrations there was no voltage and lights. I beliewe it is dead except section for heating voltage.
Also there is a bunch of cables that comes from input voltage switcher and that makes problem.

What you can do to see if the fuse is the problem, is the following: remove ALL tubes from the radio. Then connect an AC current meter across the fuse, and apply the mains voltage.

You should measure very little current. Best is to include a 1A fuse in series with your meter to avoid damaging the (expensive) fuse inside the meter.

There are other methods to try, but since you are already having problems finding out which connection on a transformer is which, I think it is best to ask for some help from someone near to you, to look at the radio together.
You might do more damage to the radio or other things than necessary.

Best regards,

Matthias

Philips/B6X12A - Power transformer connection

door svetolik, 27.02.2011, 17:00 (5019 dagen geleden) @ Matthias Meijer

Thanks a lot Matthias
I will give a shoot with the traf that I have. It has 120W of power and voltages are matched.
I have droped HV wire on to the ground, didn't see it.
Just can't aford rewinding or buying genuine one,
kind regards,
Svetolik

Philips/B6X12A - Power transformer connection

door svetolik, 28.02.2011, 14:09 (5018 dagen geleden) @ svetolik

[image]I am not sure about the thermofuse.
Here is a better picture with 4 fuzes despite that in the schematic I can see only 3 including thermofuse in the primary circuit.
Where is it exactly an hoew to reach them?
Regards

Philips/B6X12A - Power transformer connection

door Matthias Meijer @, Dordrecht, 28.02.2011, 14:23 (5018 dagen geleden) @ svetolik
Bewerkt door Matthias Meijer, 28.02.2011, 14:29

The thermofuse is located between the windings of the transformer, and is connected to the eyelets next to the cut-out piece of the frontplate of the transformer (where the black and brown sleeved wire are attached).
You can clearly see two bare tinned wires go between the transformer windings.

Desolder these wires from the eyelets, and you can gently pull it out.

The thermofuse is a small piece of plastic, approximately 15x30mm with two springy wires attached, which are soldered together through a hole in the plastic with a low melting point solder. When the transformer gets too hot, the solder melts, the wires will bend back to their original position and the current cannot flow anymore.

Best regards,

Matthias

EDIT: the two 80mA fuses are probably in the anode current circuit, one for each output tube. The 10A fuse in the filament circuit, and probably the 315mA fuse is in the high voltage circuit, right after the rectifier.
And finally the thermofuse in the primary mains circuit.

The thermofuse has the advantage over a fixed value fuse, because the primary current would be twice as high at 110V than it is at 220V. A different value fuse would then be necessary, which is sometimes the case with certain models of radios where this is CLEARLY indicated on a sticker inside the radio, and often an extra fuse is included. But this is not the case with your radio.

Philips/B6X12A - Power transformer connection

door svetolik, 01.03.2011, 08:12 (5017 dagen geleden) @ Matthias Meijer

The heating wiinding is shotrcuted to the ground.
Is this shortcut goes by transformer to the ground?

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