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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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5th Aug 2017, 10:11 pm | #41 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
Ah yes I should have attached a schematic, here it is. I have encountered thermistors before in a physics class but I wouldn't recognise one if I saw it.
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5th Aug 2017, 10:16 pm | #42 | |
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Re: Loewe Radio Zwergsuper Opta 3516GW
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Cameron |
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5th Aug 2017, 10:25 pm | #43 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
Yes we are looking at the same circuit, contacts 12,14,16 will be connected together same goes for contacts 18,20,22.
You can correlate that with the switch diagram on the schematic which I think is shown in the shortwave position, next position clockwise is medium wave, then long wave then gram. EDIT: Looking around on Google there seems to be some different chassis layouts for this receiver so far as I can make out. Lawrence. Last edited by ms660; 5th Aug 2017 at 10:35 pm. Reason: addition |
6th Aug 2017, 8:21 am | #44 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
I think there is a more common chassis which I have and a rarer one with a different layout.
Cameron |
6th Aug 2017, 12:27 pm | #45 | |
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Re: Loewe Radio Zwergsuper Opta 3516GW
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I'm not sure what the component in picture two is, whereabouts in the circuit was it? Lawrence. |
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6th Aug 2017, 2:24 pm | #46 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
It is disconnected on one side but looks as if it connects into the bulb. Thanks for the help,
Cameron |
6th Aug 2017, 2:35 pm | #47 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
If the circuit is correct then it could be one of three resistors. Have you tried measuring it?
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6th Aug 2017, 2:48 pm | #48 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
Pure speculation but as it's labelled 0.1A and the valves have 0.1A heaters it may be a thermistor for regulating the heater current. There appear to be circuit variations. Attached is another one with some variations in the power supply. Maybe that will give a clue.
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6th Aug 2017, 3:50 pm | #49 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
Google Translate from the text in the first service manual link...
"In a part of the edition, the 5volt scale lamp is replaced by an 18volt 0.1amp lamp with simultaneous installation of a Urdox resistor 2410 Pl" Lawrence. |
6th Aug 2017, 4:50 pm | #50 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
It looks like the lamp is stamped 0.12A. I wonder what the voltage is?
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6th Aug 2017, 4:53 pm | #51 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
"Urdox" is derived from "Uranium Dioxide". Later other materials were used but they all decayed in air so were generally sealed in a glass tube. This doesn't appear to be one of those. I wonder whether it's a different sort of thermistor that was installed originally or whether it was added at a later date.
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6th Aug 2017, 4:59 pm | #52 | |
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Re: Loewe Radio Zwergsuper Opta 3516GW
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6th Aug 2017, 6:34 pm | #53 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
I'm trying to measure it now but it's constantly changing which suggests it is a thermistor. It is in the 2 megaohms range now but has been up in the 3 and down in the one. I can't figure out if it's increasing resistance as it gets warmer or as it gets colder though.
EDIT - I put my crocodile clips on and let it settle and it's seems to be about the 2.2 mega ohm range at room temperature. Bringing a bulb in close seems to be bringing the resistance down, I was using my fingers to try to warm it before but I think I must have been changing the resistance. Last edited by bobskie; 6th Aug 2017 at 6:44 pm. |
6th Aug 2017, 7:06 pm | #54 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
Another question is is the resistor pictured the dropper resistor? It's a 500 ohm 15W ceramic tube resistor. It is very far out and I will certainly need to get a new one but if it is the dropper what would be a better value for UK mains voltage?
Cameron Last edited by bobskie; 6th Aug 2017 at 7:18 pm. |
6th Aug 2017, 7:30 pm | #55 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
That could be the UY11 heater substitute resistor that would have been fitted when the UY11 was replaced with the metal rectifier.
Lawrence. |
6th Aug 2017, 9:44 pm | #56 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
Possibly I can't find it on the schematic, one end is connected up to the thermistor.
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7th Aug 2017, 2:11 pm | #57 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
Further inspection today reveals more tampering had occured, on the voltage changeover section (marked spannungumschaltung on the schematic) a lot of wires appear to have been removed as shown in the picture, is this to only allow 220v operation? I have attached a picture to show what I mean. I can't really see the back row of connections very well but there are a few things attached on there.
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8th Aug 2017, 10:43 am | #58 | |
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Re: Loewe Radio Zwergsuper Opta 3516GW
Quote:
I think you have to decide whether to restore it to its original condition or whether to leave it 220V only. Whatever you do you need to check it against the circuit diagram and make sure you have the correct components in the correct places. I think personally I would just make it 240V only then you avoid the possibility that it might accidentally get switched to 110V and damaged. You can increase the dropper resistors a bit to compensate for the increase from 220v to 240V.
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8th Aug 2017, 4:45 pm | #59 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
Yes I think that's what I'll do there is no point over complicating things. It has written on the back 220v only so I assume it has been converted for 220v operation. I have placed a bid on a rectifier valve so I can get rid of the metal rectifier and restore most of the wiring to original. I have still not found where that blue wire fell from though so there is still something else disconnected, it's going to take a long time to go through the whole diagram but I suppose I'll need to.
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8th Aug 2017, 5:17 pm | #60 |
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Re: Loewe Radio Zwergsuper Opta 3516GW
I wouldn't go through the whole circuit diagram trying to find out where it might have been attached. Just get the power supply working first by reconstructing what's in the circuit diagram. Then if the radio doesn't work try to find the faults. Maybe it will be obvious where the blue wire belongs when you find a fault. On the other hand it may belong to the power supply mods and not be useful for anything.
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