Dynatron Ether Conqueror restoration

[Angus69]

Split from this thread

https://www.vintage-radio.net/forum/...d.php?t=174890


Good evening
I resume the discussion, I disassembled to clean the components, I found the current transformer from 140v to 220v, this explains why the radio works ... and then a user advised me to replace A couple of capacitors under the amplifier chassis , I posted the photos, could someone please point them to me?
and then another thing, I noticed there are a couple of loose wires (photo 2)
it's normal?
Thanks

[Techman]

The 3 capacitors are the round metal cased ones that can be seen clamped to the inside of the chassis. They're quite good quality ones and some people risk leaving them in circuit, but the reality is that they will have some leakage, albeit well up in the meg ohm range. Don't attempt to remove them, but unsolder the leads from where they're connected to and bend these leads back out of the way. Solder in new replacements of 0.1uf rated at 630 volts - do them one at a time so you don't make mistakes. The capacitors are C2, C3 & C4, the circuit diagram is shown in the picture below. Only attempt the work if you feel competent to do so. If you wanted to try the gram first, it should be ok to power it up for just a few minutes to check what is and isn't working, as it seems that the previous owner has already done this anyway. The two large valves should glow with an only just visible dull orange glow to their heater strings. The valve on the far right is the rectifier and will glow brighter than the others. If those two large valves look like they're glowing brighter than I've just described, switch off immediately!

When working on the chassis it's best to carefully remove those two large valves and store them safely, as if you break them they'll cost you hundreds to replace, so be careful!

The wires that are off should fit on the two missing terminals (someone's been messing with it and lost them), follow the wiring down to exactly the same terminals at the bottom of the cabinet to ascertain the correct ones to connect to. The radio won't receive stations properly without these connected, so you'll have to find some nuts with the same thread to replace them. You may need an external aerial wire connected to one of those bottom terminals to receive stations.

[Angus69]

thanks for reply
this is good ?

[Angus69]

The capacitors are this 3 indicated ?

[Techman]

Yes, they're the ones as far as I can tell, but check against the circuit diagram that I've posted - all the information is there. The replacements you show are the correct type.

The reason for leaving the old ones in their clamps is that value (in monetary terms as well as historic) very much depends on originality and someone in the future may want to hollow out those old capacitors and fit the new replacements inside. Leaving the old ones in their clamps, but not in circuit anymore gives anyone, or even yourself one day, the choice of doing this, even though you may argue that these components can't be seen - remember, that amplifier is the most valuable part of the whole gram.

There's a small electrolytic cathode bypass capacitor C10 that you could replace to be perfect. It's 50uf at 12 volts, however, this value is no longer obtainable, so you'd have to go for a nearest value at 47uf at a voltage above 12 volts, probably at least 25 volts. You'll have to work out from the circuit where it is or I may have some pictures of it on file if I have a search, but no promises. With a bit of luck nothing else needs touching under that chassis.

[Angus69]

Sorry,Is this ?

[Techman]

No, if you mean the electrolytic and if you're referring to the grey square unit.

I have said that you need to follow the circuit diagram, but I suspect that you're not doing this, otherwise you'd have identified the correct component - the one I think you're showing has a value marked on it which you'll see is not the value that I mentioned and also not as quoted on the circuit diagram. I am seriously worried about whether you have the ability to work on this unit, particularly if you can't follow what is actually quite a simple circuit diagram, laid out in a very clear way - certainly a lot clearer than some. You must not touch any of those grey square units which are original block paper capacitors and don't normally cause any trouble in these amplifiers. I can't remember where the particular capacitor is and I don't think I have a picture showing it, so if you can't identify it, then I would advise you to leave it for the time being.

I'm having to be quite honest and direct with you over this, as mistakes will be costly...to you!

I've found a picture from a few years ago to show you an amplifier that I worked on and showing the conservation restoration type repair with the original capacitors still in their clamps, but with the new capacitors soldered in their place - this shows 400 volt types that were available at the time and are more than adequate. However, 630 volt rated types that I advised and you pictured are the normal types for use in these positions and which are available today.

Anything else you're not sure about, ask before you dive in. Other members will be able to advise you as well - hopefully we'll all be in agreement, but you never know when it comes to these things.

Picture below of a Dynatron amplifier under chassis the same as yours with the three replacement capacitors fitted for your reference of how it should be done and what it should look like...and have another look for C10 - you know its value and it will be a round one, it could be the other one shown in the picture, but I can't remember.

[Techman]

As above - I think the one with the clear plastic outer is the one, as I can't see what else it could be - check its value and voltage.

I did replace it in that amplifier, but obviously not when that picture was taken - remember, electrolytic capacitors MUST be connected the correct way round and the same as the original one is...they explode if you get them wrong!

I'm going to have a look to see if any picture still exists of this particular component being replaced - I couldn't find one of it earlier.

[Techman]

As another quick addition - values of capacitors were often marked differently back when this gram was made and you'll notice that the square one is marked at 2 MFD, this is 2uf, so you need to be aware of this, as the electrolytic that you're looking for could be marked in 'MFD' rather than 'uf'. The value of only 2uf should indicate to you that this is not the capacitor you're looking for as you already know you're looking for one marked at 50uf.

Once you can get your head round all this, you stand a chance of getting this gram up and running, although I think if there's anything much wrong with the radio tuner part then you're going to struggle, as it's a complex unit and there's no 'full' circuit information available for it, just a basic one, so you'll need to keep your fingers crossed about that one. I already notice some differences in that there's extra screening incorporated in the shape of screened wire for the aerial interconnections - having this wiring unscreened means that the radio often works quite well without an external aerial connected to those bottom terminals, but with them screened as they are now it'll struggle without one. There also seems to be added foil screening behind the tuner chassis - I've never seen that before on a UK model, so perhaps this was a special specification for the particular country it was exported to.

[dave walsh]

As I commented in the first thread Angus [p22], the enthusiasts here can be relied on and Techman has already demonstrated this. Your own interest in restoration is commendable but do watch your step. There's very little there [in real terms] without intact valves and if you look at some of the other RG projects it's clear this can be a painstaking and highly skilled task if the historical, personal and financial value of the Radiogram is to be regained. It's great that you do intend to keep it intact but it's not hard to achieve the opposite effect [I've done something similar myself]. It might perhaps help those advising you if you say something about your technical background? Apologies if this is more than appears to be the case. We simply can't tell

I didn't purchase one of these at the Battle Auctions twenty years ago [lack of time and a suitable vehicle]. It was in excellent condition. Do I regret this-well no! I might have stripped out the Tuner Unit It was a very different time when RG's had little value, even the rare ones, plus you had to know that they were rare

Dave

[Angus69]

I thank Techman for the time he is dedicating and the explanations given, I am a bit dim with the welds, but I am not very familiar with the schematics ... I think I have identified the capacitor, placed the photos, and if everything goes well I will send the photos with the new capacitors

[Angus69]

and sorry for my very bad english ....

[Nickthedentist]

Your English is not bad at all, and very easy to understand.

[Herald1360]

Originally Posted by Angus69

I thank Techman for the time he is dedicating and the explanations given, I am a bit dim with the welds, but I am not very familiar with the schematics ... I think I have identified the capacitor, placed the photos, and if everything goes well I will send the photos with the new capacitors

That's definitely a 50uF electrolytic capacitor in the picture.

[Angus69]

I find this , 0.1 uF 1000 volts , are good or Need only 630 volts ?

[Techman]

That capacitor type will be fine.

You've probably noticed that modern capacitors are physically smaller than the original ones, so the one you've shown being a higher voltage type will be slightly larger in physical size than the 630 volt type, which you could argue would be more in keeping with the original components used in the chassis.

The replacement for the electrolytic 50uf capacitor will be a lot smaller than the original one - note which way round the original one was connected and make sure you connect any replacement the same way round, otherwise it won't work and is likely to go bang and may do some damage.

[Angus69]

I find electrolytic 47 uF capacitor more big , 100v , Is good this too or i need 47 uF 25 volts?
Sorry but i am a novice...

[Herald1360]

100V will be OK instead of 25V.

It's not recommended to run electrolytics well below their rated voltage but 25% should be fine.

[Angus69]

I turned everything on, I still haven't changed the capacitors ... the only noises you hear are when you move the selectors, of the band, base or treble, the volume doesn't go up, I tested the knob of the volume with the tester and it works ...what should I watch?

[Angus69]

Some photos