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Johnbarn · 10th Nov 2018, 1:04 am

I got this set given to me several months ago but have only started work on it this week. I downloaded the circuit diagram which called it a "Pembroke" and gave it the Model number 2068/3D but it looks pretty close to what I have. I have never worked on a Grundig before and the circuit is quite odd and it is laid out in the European DIN style. The Grundig components in the set were quite distinctive and marked with clearly readable values. Initial testing through my lamp dropper showed a heavy current drain. The two 50uF electolytics in the one can had leaked and whilst one was ok the other was showing a low resistance on an AVO. They were replaced. The HT was low and the Siemens bridge was replaced with a chunky one from RS. Further testing through the lamp dropper gave the right result - initial glow followed by a low dim. When the lamp bypass switch was closed the set gave a promising hum and one station could just be heard on MW. Then there was a wisp of smoke and I switched off immediately. The smoke was traced to a 22k 1/2 watt resistor R37 on the diagram feeding a second LS acting as an electrostatic tweeter(? - it is shown in the circuit diagram with a capacitor symbol internal to the unit).This resistor was not an original Grundig one but a typical UK three-band plus silver component the bands of which were burned. There was also a Dubilier capacitor for C70, again not a Grundig original. I tested the capacitor and it was fine. I then removed the resistor and it was reading low. I replaced it with a new one and retested the set. Again smoke from the same resistor. I switched off again and connected a meter in series with the resistor; the current through the resistor was measured at 0.084mA which means the resistor is trying to dissipate over 100W. As a next step in the process I temporarily wired in a 22k 15W w/w resistor and the set began working well on MW. The resistor was barely warm. I suspect the electrostatic LS is low and I will remove it before any further testing. Stations on the MW are plentiful but the LW BBC station is barely audible and the VHF is not operating at all.The EM81 tuning indicator is not showing anything even with a good signal on MW. I have checked the operation of the piano key wavechange and PU switches and cleaned them as much as possible with switch cleaner, though they are hard to get at. Has anyone any experience of this set and could point me in the right direction? It is beautifully made and, even though it has been "got at" at some time in the past, it is in reasonable condition inside and out.

10th Nov 2018, 1:04 am	#1
Johnbarn Pentode Join Date: Feb 2015 Location: Belfast, Northern Ireland, UK. Posts: 130	Grundig 2068 I got this set given to me several months ago but have only started work on it this week. I downloaded the circuit diagram which called it a "Pembroke" and gave it the Model number 2068/3D but it looks pretty close to what I have. I have never worked on a Grundig before and the circuit is quite odd and it is laid out in the European DIN style. The Grundig components in the set were quite distinctive and marked with clearly readable values. Initial testing through my lamp dropper showed a heavy current drain. The two 50uF electolytics in the one can had leaked and whilst one was ok the other was showing a low resistance on an AVO. They were replaced. The HT was low and the Siemens bridge was replaced with a chunky one from RS. Further testing through the lamp dropper gave the right result - initial glow followed by a low dim. When the lamp bypass switch was closed the set gave a promising hum and one station could just be heard on MW. Then there was a wisp of smoke and I switched off immediately. The smoke was traced to a 22k 1/2 watt resistor R37 on the diagram feeding a second LS acting as an electrostatic tweeter(? - it is shown in the circuit diagram with a capacitor symbol internal to the unit).This resistor was not an original Grundig one but a typical UK three-band plus silver component the bands of which were burned. There was also a Dubilier capacitor for C70, again not a Grundig original. I tested the capacitor and it was fine. I then removed the resistor and it was reading low. I replaced it with a new one and retested the set. Again smoke from the same resistor. I switched off again and connected a meter in series with the resistor; the current through the resistor was measured at 0.084mA which means the resistor is trying to dissipate over 100W. As a next step in the process I temporarily wired in a 22k 15W w/w resistor and the set began working well on MW. The resistor was barely warm. I suspect the electrostatic LS is low and I will remove it before any further testing. Stations on the MW are plentiful but the LW BBC station is barely audible and the VHF is not operating at all.The EM81 tuning indicator is not showing anything even with a good signal on MW. I have checked the operation of the piano key wavechange and PU switches and cleaned them as much as possible with switch cleaner, though they are hard to get at. Has anyone any experience of this set and could point me in the right direction? It is beautifully made and, even though it has been "got at" at some time in the past, it is in reasonable condition inside and out.