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Old 13th Oct 2018, 10:50 am   #1
Mrgroovy
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Default Radionette Kurér - Need help identifying component

Hi,

While waiting for new parts for my AH37, I thought I'd pick up where I left a few weeks back on my Radionette Kurér. I have the schematics and all, and as for now I'm just going to replace all four electrolytics. Three of the four are easily identifiable, whereas the last one is a bit more tricky.
I think I have found it, though it certainly doesn't look like any electrolytic capacitor I've ever seen. Take a look at the attached photos. The only markings I can see on it is a 6+. If anything that would be the positive/plus side? The capacitor in question is the 100uF 12V. It is so small that I'm not even sure it could be an electrolytic, but following the schematics it appears to be the one. Seeing that there is voltage rating (12v) and quite high capacitance 100uF I automatically assumed it was an electrolytic, but if it is not it would probably not be a good idea to swap it out? Maybe some of you can demystify this by having a look at the schematics and the photos?

Thanks!

Btw, the other three electrolytics are made by Hunts; probably known to most of you.
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Old 13th Oct 2018, 11:34 am   #2
govjohn
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Default Re: Radionette Kurér - Need help identifying component

Hi, Mrgroovy the object shown in the photo's is a diode, almost certainly the one in parallel with the DK96 heaters. The 100Mfd capacitor is used to decouple the bias supply derived from a tap on the series heater chain. It will certainly be a electrolytic and it is connected to the + side of the diode I can't identify it in the pictures but it will be in there somewhere! It will only have a couple of volts accross it. A 100Mfd 16V capacitor would be ideal as a replacement and you will find it a heck of a lot smaller than what is in there. Good luck.
John.
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Old 13th Oct 2018, 11:40 am   #3
ms660
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Default Re: Radionette Kurér - Need help identifying component

That looks like a stabilizing/protection diode "+9" It might be connected across the 100uF 12 volt electrolytic in the power supply, have a scroll down this lot to schematic number "X" and you will come across the "+9" type :

http://www.nrhf.no/Skjemabank/Radion...rer%20Auto.pdf

Lawrence.

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Old 13th Oct 2018, 11:54 am   #4
Mrgroovy
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Default Re: Radionette Kurér - Need help identifying component

Quote:
Originally Posted by govjohn View Post
Hi, Mrgroovy the object shown in the photo's is a diode, almost certainly the one in parallel with the DK96 heaters. The 100Mfd capacitor is used to decouple the bias supply derived from a tap on the series heater chain. It will certainly be a electrolytic and it is connected to the + side of the diode I can't identify it in the pictures but it will be in there somewhere! It will only have a couple of volts accross it. A 100Mfd 16V capacitor would be ideal as a replacement and you will find it a heck of a lot smaller than what is in there. Good luck.
John.
Hi John. Thank you for clearing that out!

Could I please ask you to have another look at the schematics where I made the red circles? There are supposed to be 4 electrolytics in this unit, right? I can only find three, so that is why I thought the diode could have something to do with it. One of the electrolytics are a multi section tube with a 50uF/150V and a 150uF/150V, while the other one is a 100uF/12V, all these three easily found... But then where could the last 100uF/12 be?
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Old 13th Oct 2018, 12:04 pm   #5
ms660
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Default Re: Radionette Kurér - Need help identifying component

Trace the DL96 filament centre tap back to the 680 ohm resistor, the 100uF should be connected to the other side of that resistor somewhere according to your schematic.

Lawrence.
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Old 13th Oct 2018, 12:13 pm   #6
Mrgroovy
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Default Re: Radionette Kurér - Need help identifying component

Thanks, I'll try do that, but just to be clear, there should in fact be 4 electrolytics, and not just 3? I really can't see how a vintage electrolytic can find a place to hide in this old portable radio considering the size of the other 2(3)...
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Old 13th Oct 2018, 1:32 pm   #7
govjohn
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Default Re: Radionette Kurér - Need help identifying component

With reference to the missing capacitor, if you really can't find it its quite possible it was found unnecessary and just left out. Try it without, if get any problems you can all ways fit one. John.
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Old 14th Oct 2018, 11:26 am   #8
Mrgroovy
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Default Re: Radionette Kurér - Need help identifying component

It's a good chance you're right about that. However, I have three of these radios. One of these are identical to this one which means I can't find the fourth electrolytic in that second one either. The third has a different, slightly bigger multi-section electrolytic aluminum(?) tube with 3 capacitors in it instead of 2, but it also has this fourth electrolytic which I'm unable to localize in those other two. I'll have to scrutinize this even further and come back to this when I've had chance to look more into it.
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Old 14th Oct 2018, 12:26 pm   #9
ms660
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Default Re: Radionette Kurér - Need help identifying component

In the link below, the writing on the blue under chassis Plessey electrolytic suggests that there might be two low voltage capacitors contained within?

http://www.blooo.fr/radio/tsf/radion...tronique_B.jpg

Lawrence.
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Old 14th Oct 2018, 1:12 pm   #10
Mrgroovy
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Default Re: Radionette Kurér - Need help identifying component

Lawrence, you are right! Don't know how I could have missed that. The printing says "can negative", "yellow positive" and since there are only two soldering lugs (that I see) I automatically figured one of them was ground. The capacitor is tightly fitted in a corner so it is hard to see the printing but now I found the "red positive" also using a small dentists mirror. Maybe the negative soldering lug is at the far rear end of the capacitor (crammed into the corner of of course), but I'll have to dismantle it alltogether to be able to have a look.

Thanks for all your help folks!
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Old 14th Oct 2018, 2:47 pm   #11
ms660
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Default Re: Radionette Kurér - Need help identifying component

No problem, don't forget there are two valve filament regimes with that receiver, series connected for mains operation and parallel connected for battery operation, the filaments (and electrodes) of these types of valves are very intolerant of being subjected to an excess current situation.

Lawrence.
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