Toshiba V-101 Betamax Power Source - UK Vintage Radio Repair and Restoration Discussion Forum

Libratron · 3rd Jul 2015, 4:06 pm

Hi guys,

it's arrive from Japan this portable Betamax.
My problem is to power source the 12V to this VTR.
I have DIN connector on the side of the VTR,
but don't know the correct polarity of the Power Supply.

Anyone Help me?

Libra

John123 · 3rd Jul 2015, 11:30 pm

Hi, there's a website here that has lots of pinouts for various types of connectors. The only real way to find out would be to get hold of the relevant service documentation, or maybe documentation for a similar US model.

I suppose you could try opening it up and trace back the connector to any regulators, and then find out the polarity and power requirements that way.

Libratron · 3rd Jul 2015, 11:41 pm

Thanks John.

The primary thing, is to find the GND pin.
And check to find the 12V pin with a DIN connector.

The problem of this machine is completely compact.
And is very difficult to check the trace of the PSU.

The service documentation is impossible to find on the web.

Hovewer thanks for the answer.

Libra

julie_m · 4th Jul 2015, 7:37 am

It's not old enough to be PNP-based, so the chassis will almost certainly be negative and the supply rail positive. What I would do is use a digital multimeter to test for continuity between each of the DIN socket pins and chassis to find the 0V pin(s).

If you are feeling brave, and have a suitable bench PSU, you could try applying the correct voltage via a damage-limiting 10 kΩ series resistor, to each non-ground pin in turn; and measuring the voltage between the pin and 0V. Anything that is an audio or logic input or output or a video output should present a high resistance, and leave most of the supply voltage across the input. But at least one of the pins will present a low resistance, and the voltage across the input will drop. Now, this could be a 75Ω video input, or it could be the power input. So disconnect the power supply while continuing to measure the voltage. If it drops suddenly to zero, that means there is most probably a resistor from the pin to ground, suggesting a video input; whereas if it decays more slowly, that means there is most probably a capacitor from there to ground, suggesting power-in. A further check with a DMM should show 75 Ω whichever way around the probes are connected for a video input, and probably different readings each way for the power supply input.

Nicklyons2 · 4th Jul 2015, 9:08 am

The -ve pin should be easily found because, with a meter it will almost certainly show 'short circuit or very low resistance to the shield on the 'phono' and earphone plugs.

Now I don't know this particular machine but the usual idea with multi-pole connectors on the power was to have the 'running' 12V supply on one set of pins and an (internal) battery charging supply on the others. The mains PSU usually had a run-charge switch; this would give say 12v regulated to the machine in the normal operate mode and around 14 to 15 volts (to the other pins) in battery charge mode.

I would try and meter for the -ve as described above; next couple up a suitable (4amp min) stabilised PSU to the battery connectors - make sure you get the polarity correct. Next meter the DIN socket and see whether the 12V is available there.

Many VCRs of this era used 2 X 6Volt sealed lead acid batteries in series, some even had PP9 style press studs on top - all I'm saying is check and double check the polarity before powering up. I think you'll find that the battery -ve and the phono and jack shields are 'common'. If the worst comes to the worst just use an LCD TVs 12v 4 to 6 Amp power 'brick' connected up to the battery compartment and ignore the DIN.

Hope all this helps, Nick

julie_m · 4th Jul 2015, 9:56 am

Quote:

Originally Posted by Nicklyons2

If the worst comes to the worst just use an LCD TVs 12v 4 to 6 Amp power 'brick' connected up to the battery compartment and ignore the DIN.

Why didn't I think of that? Nice one!

And yes, I'd forgotten all about any charge control being done at the PSU end as opposed to the appliance end.

Must be too much exposure to modern kit .....

Libratron · 4th Jul 2015, 11:58 am

Thanks very much guys.

Libra

dj_fivos_sak · 7th Aug 2015, 4:45 am

That looks like a clone of the Sanyo VPR-4800/5800 portable Beta. They should use the same connector.

3rd Jul 2015, 4:06 pm	#1
Libratron Pentode Join Date: Jun 2011 Location: San Martino di Lupari, Veneto, Italy. Posts: 204	Toshiba V-101 Betamax Power Source Hi guys, it's arrive from Japan this portable Betamax. My problem is to power source the 12V to this VTR. I have DIN connector on the side of the VTR, but don't know the correct polarity of the Power Supply. Anyone Help me? Libra Attached Thumbnails

3rd Jul 2015, 11:30 pm	#2
John123 Heptode Join Date: Jan 2007 Location: Luton, Bedfordshire, UK. Posts: 891	Re: Toshiba V-101 Betamax Power Source Hi, there's a website here that has lots of pinouts for various types of connectors. The only real way to find out would be to get hold of the relevant service documentation, or maybe documentation for a similar US model. I suppose you could try opening it up and trace back the connector to any regulators, and then find out the polarity and power requirements that way. __________________ Regards, John

3rd Jul 2015, 11:41 pm	#3
Libratron Pentode Join Date: Jun 2011 Location: San Martino di Lupari, Veneto, Italy. Posts: 204	Re: Toshiba V-101 Betamax Power Source Thanks John. The primary thing, is to find the GND pin. And check to find the 12V pin with a DIN connector. The problem of this machine is completely compact. And is very difficult to check the trace of the PSU. The service documentation is impossible to find on the web. Hovewer thanks for the answer. Libra

4th Jul 2015, 7:37 am	#4
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Toshiba V-101 Betamax Power Source It's not old enough to be PNP-based, so the chassis will almost certainly be negative and the supply rail positive. What I would do is use a digital multimeter to test for continuity between each of the DIN socket pins and chassis to find the 0V pin(s). If you are feeling brave, and have a suitable bench PSU, you could try applying the correct voltage via a damage-limiting 10 kΩ series resistor, to each non-ground pin in turn; and measuring the voltage between the pin and 0V. Anything that is an audio or logic input or output or a video output should present a high resistance, and leave most of the supply voltage across the input. But at least one of the pins will present a low resistance, and the voltage across the input will drop. Now, this could be a 75Ω video input, or it could be the power input. So disconnect the power supply while continuing to measure the voltage. If it drops suddenly to zero, that means there is most probably a resistor from the pin to ground, suggesting a video input; whereas if it decays more slowly, that means there is most probably a capacitor from there to ground, suggesting power-in. A further check with a DMM should show 75 Ω whichever way around the probes are connected for a video input, and probably different readings each way for the power supply input. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

4th Jul 2015, 9:08 am	#5
Nicklyons2 Octode Join Date: Jan 2013 Location: Barnsley, South Yorkshire, UK. Posts: 1,517	Re: Toshiba V-101 Betamax Power Source The -ve pin should be easily found because, with a meter it will almost certainly show 'short circuit or very low resistance to the shield on the 'phono' and earphone plugs. Now I don't know this particular machine but the usual idea with multi-pole connectors on the power was to have the 'running' 12V supply on one set of pins and an (internal) battery charging supply on the others. The mains PSU usually had a run-charge switch; this would give say 12v regulated to the machine in the normal operate mode and around 14 to 15 volts (to the other pins) in battery charge mode. I would try and meter for the -ve as described above; next couple up a suitable (4amp min) stabilised PSU to the battery connectors - make sure you get the polarity correct. Next meter the DIN socket and see whether the 12V is available there. Many VCRs of this era used 2 X 6Volt sealed lead acid batteries in series, some even had PP9 style press studs on top - all I'm saying is check and double check the polarity before powering up. I think you'll find that the battery -ve and the phono and jack shields are 'common'. If the worst comes to the worst just use an LCD TVs 12v 4 to 6 Amp power 'brick' connected up to the battery compartment and ignore the DIN. Hope all this helps, Nick

4th Jul 2015, 11:58 am	#7
Libratron Pentode Join Date: Jun 2011 Location: San Martino di Lupari, Veneto, Italy. Posts: 204	Re: Toshiba V-101 Betamax Power Source Thanks very much guys. Libra

7th Aug 2015, 4:45 am	#8
dj_fivos_sak Heptode Join Date: Mar 2015 Location: Lefkada, Greece Posts: 969	Re: Toshiba V-101 Betamax Power Source That looks like a clone of the Sanyo VPR-4800/5800 portable Beta. They should use the same connector.