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Techman · 4th Jun 2019, 9:33 pm

Hi Dom,

Since I posted earlier I've remembered that the capacitor that goes very leaky and takes out a resistor must connect directly or indirectly to the EL84 anode, so will be taking excess HT current through the output transformer primary. I was going to post again with the fault symptoms, but you've beaten me to it - yes, the immediately noticeable fault symptom is slight crackling and noise through the loudspeaker from first switch on and before any of the valves have warmed up. Don't run the set again until you've replaced both the capacitor and its associated resistor.

The main smoothing electrolytic may recover, but if it still seems to be getting warm then it may have to be replaced. I have to admit that the double smoothing electrolytic can in my set has the same dried electrolyte leakage evidence. Several years ago the reservoir section went open circuit and as a temporary fix I just connected a single electrolytic in place of the dud section and it's still working perfectly like this, possibly five years later. The warming of the can of your capacitor does indicate that it could be terminal, but keep an eye on the temperature and it may recover, however, the fact that it's blown its end seal slightly does indicate that it's not in a good state.

4th Jun 2019, 9:33 pm	#7
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: Grundig 3028 3D Hi Dom, Since I posted earlier I've remembered that the capacitor that goes very leaky and takes out a resistor must connect directly or indirectly to the EL84 anode, so will be taking excess HT current through the output transformer primary. I was going to post again with the fault symptoms, but you've beaten me to it - yes, the immediately noticeable fault symptom is slight crackling and noise through the loudspeaker from first switch on and before any of the valves have warmed up. Don't run the set again until you've replaced both the capacitor and its associated resistor. The main smoothing electrolytic may recover, but if it still seems to be getting warm then it may have to be replaced. I have to admit that the double smoothing electrolytic can in my set has the same dried electrolyte leakage evidence. Several years ago the reservoir section went open circuit and as a temporary fix I just connected a single electrolytic in place of the dud section and it's still working perfectly like this, possibly five years later. The warming of the can of your capacitor does indicate that it could be terminal, but keep an eye on the temperature and it may recover, however, the fact that it's blown its end seal slightly does indicate that it's not in a good state.