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Old 30th Oct 2019, 10:24 am   #111
DonaldStott
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Join Date: Aug 2015
Location: Glasgow, UK.
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Default Re: Kolster-Brandes MR10

I also checked the replacement V1, a 12AT7WA kindly supplied by Forum member David G4EBT as this set was completely silent on FM previously.

Pin 1 - Anode (a) 168V
Pin 6 - Anode (b) 160V
Pin 3 - Cathode (a) 1.14V

Slightly down on what they should be so I'll go back and do a final check on all components in the FM stage shown in the picture below but I have been wary of replacing anything here for fear of upsetting the alignment.

There is a Hunts cap in the middle left which may need replaced - anything else that's obvious?

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Also with V1 we have: -

Grid Voltage: -1.13V
Cathode Voltage 1.13V

Resistors across the set will need a final sweep as I seem to remember that some of them were marginal.

In Post #76 above I mentioned issues with the Tone Control which is very bright and harsh with a lot of sibilance! You can only turn the control a very small way round before the audio becomes too harsh to listen to! Don't really want to think about replacing this switch/pot so what are my options to alleviate this issue? From the Trader Service Sheet 1233 I note that between the Anode of V5 and the Output Transformer we have R23 (4.7kΩ) and C44 (0.01μF) in series. Would increasing the value of any of these help - if so, what values would be recommended??

On the home straight now, hopefully ...
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Last edited by DonaldStott; 30th Oct 2019 at 10:46 am. Reason: Typo
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