Thorn 6204 hum after fitting new plug wire

[DMcMahon]

Originally Posted by MisterKrupa

Ah cheers David, you may have saved me a disappointing purchase, or two ...

They are still very useful for the actual Tape Deck itself.

Davids

[DMcMahon]

Originally Posted by MisterKrupa

It was pretty quick and easy, seems to have done the trick, all back together and functioning as well as it was on Monday!

I'll still maybe try and fit a better socket solution at some point, and maybe try and figure out either a DIN cable breakout thing for the back, or some way of shutting off the speaker.

Well done Chris, sounds like it is fixed. I must have missed it, what is the socket issue ?

David

[MisterKrupa]

Cheers David, it’s really nice to fix something like this myself

In terms of the socket thing, I was thinking, even before it was mentioned about the UK regs, that a kettle type socket would be a good thing to fit instead of just having a mains lead winding its way into the case directly to a soldered mount. I guess there would be less chance of breakage from the cord pulling this way and that, plus I’d have options of what to pull out in case of emergency...

[majoconz]

Happy to hear that you have got it working much better now.

Aren't those kettle plugs reversible and rely on a couple of leaf springs to make the earth connection? That would make them a no-no to me. I would much prefer the normal computer type IEC plug/socket.

[MisterKrupa]

That’s what I meant, I’m probably using the wrong term

[Lucien Nunes]

'Kettle lead' is recognised as an IEC C13 lead in many industries, even though very few kettles ever used the standard type and none do today. But here in the vintage domain we tend to be a bit more specific and it can be read as one of two popular types of lead historically used on kettles.

Personally, I wouldn't fit one. If the existing cable is not secure, it's often possible to cable-tie it to something sturdy in a couple of places, out of the way of any hot or moving parts. You don't need the connector for isolation, get into the habit of pulling the plug out of the wall socket, which works for everything.

But I do urge you to change at least the output stage coupling capacitor and possibly cathode bypass capacitor before using the machine much, unless they have been done already or are trustworthy types. A leaky paper capacitor could be progressively damaging the output valve and overheating the transformer unnoticed all the time the machine is powered up, even while it is apparently functioning correctly. Then, clean and demagnetise the heads and tape path and play to your heart's content.

[MisterKrupa]

Cheers Lucien, I have cable tied what I have, so perhaps it's fine as is, and urging acknowledged, I may well take it to a mate who spends his days restoring gear in Preston, until then, it's only likely to get sporadic short usage in any case...

[Station X]

Originally Posted by MisterKrupa

urging acknowledged, I may well take it to a mate who spends his days restoring gear in Preston, until then, it's only likely to get sporadic short usage in any case...

I've been a member of these forums for more than 20 years and I've lost count of the number of posts I've seen from new members which go something like this:-

...I plugged it in and it worked fine for a couple of hours then smoke came out. Where can I get a new mains/output transformer from?

You have been warned.

[MisterKrupa]

Yeah, I get it, an hear it, I'm just very well aware of my own limitations; I ended up seeking help here due to a break I made while attempting a much more basic fix. I'm just about able to manage basic soldering, but replacing those caps looks like a serious job to me, it'll get done I'm sure...

[dazzlevision]

Further to post 46, I’ve restored a few of these Thorn group tape recorders and there are a few Hunts “Moldseals” capacitors used, which will be faulty and should be replaced. I spotted at least two (brown in colour) in one of the photos in post 27.

[Graham G3ZVT]

I had the Marconphone version of this machine when I was a kid, I damaged the track selector switch, and remember how apprehensive I was about replacing it, as it was the most complex job I'd undertaken since teaching myself to solder.
Anyhow I got it done eventually.

It had a B9A accessory socket on the back which (amongst other things) allowed you to monitor the other track whilst recording, not a feature you'd expect on a budget machine like this.

[MisterKrupa]

Yeah that socket sounds very interesting from what I’ve read.

[DMcMahon]

Originally Posted by MisterKrupa

replacing those caps looks like a serious job to me, it'll get done I'm sure...

Replacing coupling capacitors can vary from very simple to very difficult depending upon several things, particularly their physical location. On some recorders some of the capacitors may be buried under lots of other components and cables which can make it difficult to locate, identify and access them.

On your unit an example of a simple one is the 0.01uF connected to the volume control wiper (middle connection) as per Post 27 4th photo. This electrically connects through to the control grid (pin 2) of the ECC83 (V1B) second stage.

Just for information there is a second coupling capacitor (0.005uF) that connects to the end of the screened cable that connects to the volume control LHS connection. This capacitor connects to the anode output (pin 6) of the first stage of the ECC 83 (V1A). This capacitor connection most likely connects direct (could connect via a terminal strip) to pin 6 together with anode 220k load resistor.

I should stress that these 2 capacitors are not the ones that would be of concern for the output transformer.

David