grundig: 87WE; Musikgerät

Fellow RMorg Members,

                                  I have just dug this model out of my "to do" pile in my garage where it rested along with perhaps 70 others.

Although eventually (you`ll understand why I say this) the unit works very well, on start-up it exhibits a curious phenomenon: initially, after about a minute, the sound comes through perfectly for about 5 seconds; it then `clicks off``(the radio stays illuminated), and doesn`t come back to sound until a further minute or so.

This start-up timing is almost always exactly the same - 1 minute followed by 5 seconds followed by another minute, then "bingo" it works more or less normally - very occasionally it goes through the "click off/click on" procedure several times in rapid succession.

Anyone any idea where a very amateur radio collector should start looking to get rid of this irritating fault - the radio is eventually destined for use in a bedroom?

g.guy

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I had effect on a Siemens where after about a minute the audio quality would change and EM84 go out. Occasionally it would come back on again after a few seconds, for a few seconds, with associated clicks and change in audio quality.

You had to turn of the radio for several minutes to reset the process. A replacement Chinese 6E2 Magic Eye works perfectly. Though with the meter I couldn't see any change in grid voltage or other electrodes, or HT, the changes in audio quality (amount of treble) significant when the EM84 went on and off. The main HT would gradually drop as the set warmed up.  I am temped to test the EM84 with reduced heater voltage.

I can only presume that as it heated up it was shorting partially in some fashion not obvious to my DMM measurements.

It's possible you have one faulty part or valve/tube that is creating an intermittant short or extra load as the radio heats up?

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Graham, the 87WE may be dangerous. There is no transformer for separating the line from chassis. The Autotransformer uses the primary winding also for the Anode-voltage. So do not touch the chassis or any metal component as long as the power line is connected. Do not try to measure any voltage without using an external  transformer.

If you connect the line plug so, that ground is on chassis, the danger is lower, but not save. In that case a 10mA FI safety plugin-automate is a good thing. 

I think such a radio is collactible, but it is not the best idea to use it in bedroom.

Did you replace the defect paper capacitors? They look often defect and they are. Moist went inside and the internal isolation became bad.

If you have a safety transformer, you should measure the voltage, as they are printed in the schema next to tube sockets.

 Heribert Jung

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