Broadcaster Gramette help

Hi

I'm restoring a Broadcaster Gramette, my first project of this kind, I wonder if anyone could tell me if the brass centre peg should be attached to the plastic platter or if it is supposed to be free to spin on it, there are some hairline cracks on the platter around the hole and I'm not sure if its supposed to be attached or not? Pic attached..

Many thanks
Andy

In addition to the above the audio output is very low, it needs a stylus but bridging the cartridge wires doesn't really make a considerable different to the audio output which I'm told would suggest an issue with the amplifier. Unfortunately I'm a bit lost as to where to start with this, could someone suggest any tests I could do to try and diagnose further. Also there is a white wire coming from the motor which appears to have been cut but I cant see anywhere that it should connect to? Any help or suggestions would be greatly appreciated ! Some photos attached:

[Edward Huggins]

From memory, the brass spindle is attached to the turntable and it pops on to the motor spindle underneath. A stylus is unlikely to affect the volume, but a faulty cartridge would. If you get a healthy buzz from the amplifer when touching the cartridge wires, then it suggests the cartridge has failed. A replacement will cost £35.00 - BUT - it will only be able to play older Mono records and not Stereo. Leave the white wire coming from the motor, you do not need it. Your Gramette was made by Dansette in 1955.

[toshiba tony]

Not being familiar with this model but it's a safe bet the white wire is for models with series wired valve heaters. Please post some pictures of the amp.

[Station X]

That looks similar to the Dansette 14-3 amplifier, but using a UL41 valve rather than an EL84.

It's similar to the amp in this thread:-

https://www.vintage-radio.net/forum/...ad.php?t=29421

Possible circuit here:-

https://www.vintage-radio.net/forum/...d.php?t=104339

Hi all,

Thanks for the replies, shorting the cartridge wires does increase the hum but only slightly rather than considerably, I'm not sure if I should be looking to change the cartridge first or looking closer at the amplifier. The stylus is quite worn but it does play but with very low volume. I've attached some more pics as requested. I'd not considered the mono/stereo issue with the stylus/cartridge, it has the flip over type marked 78 on one side and 33 45 on the other, can I still play stereo records or is there an alternative cartridge/stylus I can fit? Would replacing any of the capacitors or valve help with the low volume?

Thanks again

Andy

[Station X]

I can see one wax paper capacitor in your second picture, probably the tone control capacitor. These caps are notoriously unreliable and I suggest changing it.

Use a meter to check the resistors which may have gone high in value.

UL41's can give problems, but changing this, unless you happen to have a known good spare, should be a last resort.

[Station X]

The component count seems to be very low. I can only spot two resistors. The 1k looks to be the smoothing resistor and the other the cathode bias resistor.

Looks like the circuit linked to in post #5 is a good bet, even if the component values are slightly different. It has voltages marked too.

[ms660]

So far as I can make out the cathode bias resistor is 180 ohms, looks like the bypass capacitor is in the can, 25uF...?

Lawrence.

[Station X]

Perhaps the OP can tell us the colour code of the cathode resistor and what it says on the electrolytic can. Then we'll be able to draw the entire circuit.

Is the capacitor date code 55 or 65?

The resistor under the valve is brown/grey/brown and measures 178 ohm with the multi-meter, the one under the electrolytic can black/red/black 1.2k , the can is 25uf and date 1955, looks very similar to the diagram in the link on post 5.

[Heatercathodeshort]

You also to check the HT voltage. A meter is required but you need to know how to use it. The contact cooled metal rectifier may well be very low output together with a faulty cartridge. The cartridge needs to be at least 800mV output to fully load the UL41. John.

[Station X]

Originally Posted by zaxxan1

The resistor under the valve is brown/grey/brown and measures 178 ohm with the multi-meter, the one under the electrolytic can black/red/black 1.2k , the can is 25uf and date 1955, looks very similar to the diagram in the link on post 5.

The 180R resistor is fine then. What does the 1k2 measure?

There will be at least two and possibly three caps in the can. Can you rotate it or use a mirror to find the other values?

If you measure the DC voltage between chassis and each of the non-earthed terminals of the can that will tell us much of what we need to know. Also check the DC voltage on the centre tag of the tone control pot.

[ms660]

Brown Black Red....1kohm.

Lawrence.

The 1k resistor measures 1.2k.

Voltage at centre tag of tone control 92 VDC.

Yellow wire on can 5.7 VDC.
Blue wire on can 103 VDC.
The bare wire on can going to the rectifier 142 VDC.

[Station X]

Those figures don't look to bad. Replacing the 1k resistor will boost the HT voltage a bit.

Does the voltage on the tone control vary as you turn the control? Try disconnecting one end of the wax paper cap. If it's electrically leaky the anode voltage will increase

the voltage varies from 92v to 99v on the centre pin when turning the tone knob. I've disconnected the wax paper cap and the voltage at the can is the same on the wire going to the rectifier at 142v, negligible 0.2v rise on the yellow wire and 1v rise on the blue. I'm assuming things are looking ok, is there any may to test the rectifier and the cartridge? What wattage resistor would I replace the 1k with?

thanks for all your help guys !

[ms660]

Just to confirm my curiosity, what coloured wire is connected to the bare wire from the rectifier on the electrolytic can?

Lawrence.

the bare wire from the rectifier is connected to the same terminal on the can as the 1k resistor (with the green sleeving on it)

[ms660]

Originally Posted by zaxxan1

the bare wire from the rectifier is connected to the same terminal on the can as the 1k resistor (with the green sleeving on it)

Yes, but what other coloured wire is connected to that capacitor terminal?

Lawrence.