Pilot Little Maestro pre war AC/DC 1939 restoration project.

[Radio Scotland]

IT LIVES

But!!! the audio is very distorted and not very loud. The oscillator is very strong on MW, Few measurements.

Rectifier 180 volts
6A8 Anode 140 volts,
Overall current draw = 0.358ma

Volume pot bypassed as it's dodgy.

Yea radio dave the switch is now on the live side

[Station X]

Are you sure about the current drawn? Is that the current drawn from the mains or the HT supply?

[Radio Scotland]

Originally Posted by Station X

Are you sure about the current drawn? Is that the current drawn from the mains or the HT supply?

That's the overall current draw meter in line with the mains plug

[Radio Scotland]

Short video of the radio working (kind of)

https://www.youtube.com/watch?v=gles6rsrgJk

[Station X]

Originally Posted by Radio Scotland

That's the overall current draw meter in line with the mains plug

Is the decimal point in the right place?

[Radio Scotland]

Originally Posted by Station X

Is the decimal point in the right place?

My mistake 0.350 Amps, Meter on the 20 amp range,

[Simon Gittins]

Well done, sounds at last!

How have you bypassed the volume control? It's also the signal diode load so that still needs to be about 250k.

[Radio Scotland]

Originally Posted by Simon Gittins

Well done, sounds at last!

How have you bypassed the volume control? It's also the signal diode load so that still needs to be about 250k.

I just realised that, Volume pot is dodgy, I hooked it back up temporarily and she sounds fantastic

[Radio Scotland]

Much obliged to all that contributed to the thread, Thought it would never end All i need to do now is try and fix the volume pot or source a new one,

By the way the HT resistor only gets slightly warm.

Heres hoping i don't need to reactivate this thread


Cheers all

[Sideband]

Originally Posted by Radio Scotland

My mistake 0.350 Amps, Meter on the 20 amp range,

That's better!! I was going to say that at 35 microamps, it wouldn't be working at all!. Well done on finally cracking the case. It's certainly been a learning curve!

[Radio Scotland]

Originally Posted by Sideband

That's better!! I was going to say that at 35 microamps, it wouldn't be working at all!. Well done on finally cracking the case. It's certainly been a learning curve!

For sure yeah, In the end what stopped it working when i first tried it was V1 installed the wrong way round due to a worn key in the valve base and a bad volume control, Glad it wasn't an error in my work

[davebms]

That was hard work for your first resto, congrats on your efforts (plus others )
enjoy

dave h

[Radio Scotland]

Cheers dave


Just when you thought you'd seen the last of this thread i'm back,

An issue has cropped up and was being discussed in my potentiometer wanted thread, But that's not the place to discuss it, Hence i'm back here again.

Story is

The way the volume pot works seems to puzzle me, It's got a centre notch like a balance control. When in the centre notch position the resistance is zero between the two outer pins which causes a short and blows the fuse. Far as i know the resistance between the two outer pins should be constant,

First half of the wiper is around 660k and can be varied, Second half is constant,

When i was adjusting the volume yesterday i saw a flash then the fuse popped, Second time it's happened whilst adjusting the volume. Seems that when the two outer pins on the pot drop to zero ohms L11 Is being shunted to ground, But L11 Shouldn't have any real voltage across it, Even if it did you'd think the coil would burn out before the fuse blew.

Very strange.


Jay

[Radio Scotland]

SOLVED

One side of the on/off switch goes to the chassis, But only when the switch is in the Off position,

As for the volume control, I must have reassembled it wrongly, Centre notch is now gone and it works perfectly,

Another lesson learned, Although i thought it originally had a centre notch, But couldn't figure out why..

[Station X]

Originally Posted by Radio Scotland

SOLVED

One side of the on/off switch goes to the chassis, But only when the switch is in the Off position.

One side of the switch should go to chassis no matter what the switch's position. When the switch in in the ON position one side of the mains (preferably neutral) is connected to chassis via the switch.

[FERNSEH]

Does your set have a single or double-pole on-off switch?
If it is a single pole switch it is better to connect it to the live mains.
However, if the volume control needs replacement, fit one with a double pole switch.

DFWB.

[Radio Scotland]

Originally Posted by Station X

One side of the switch should go to chassis no matter what the switch's position. When the switch in in the ON position one side of the mains (preferably neutral) is connected to chassis via the switch.

One side of the switch connects to the switch body only in the off position, Switch removed from radio.

Problem was i rewired the switch to switch the live not knowing about the above, I thought switching the live was preferred ?

[Station X]

Regardless of whether the switch is in the live or neutral lead it shouldn't blow a fuse.

You haven't earthed the chassis have you?

EDIT.

It must be the input or mains lead side of the switch which is grounded in the OFF position. This will short circuit the mains supply no matter which way round it's connected.

[Radio Scotland]

Originally Posted by Station X

Regardless of whether the switch is in the live or neutral lead it shouldn't blow a fuse.

You haven't earthed the chassis have you?

EDIT.

It must be the input or mains lead side of the switch which is grounded in the OFF position. This will short circuit the mains supply no matter which way round it's connected.

No the chassis hasn't been earthed, Either way she's working a treat now Just hooked it up to a long wire and she's sounding great, All thats needed now is a decent looking mains lead (using an orange one from an old strimmer) and a spit and polish,

[Radio Scotland]

finished - the end