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DIY & Tutorials
DIY For Audio
Restoration of Philips B6X63A valve radio from 1956
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<blockquote data-quote="El Sid" data-source="post: 887627" data-attributes="member: 18550"><p>The FM is being problematic - either not working at all, or working for a short (but sometimes long) while, or one time even starting again after being dead. Often when I switch from AM to FM it is on for a few seconds then dies. While it is not working there is static, and it doesn't change if I turn the tuning dial. It certainly smells like an intermittent fault caused by something thing like poor contact, dry joint or dodgy components. The AM is working which suggests to me that the IF stages are fine.</p><p></p><p>So far I have cleaned all the contacts on the 3 switches operated by the FM button, and taken the ECC85 out and cleaned its pins. Sometimes jiggling the ECC85 seems to help, but I'm not sure if it's coincidence. Next up I am going to trace out the circuit and check the components where I can, and see if I can get my hands on another ECC85.</p><p></p><p>However, RF is not my forte (RF valve circuits even less so!) so I thought I'd ask the wise men out there if they have any suggestions. I've posted the circuit diagram for reference. As an aside, the switch diagrams are completely incomprehensible.</p><p></p><p>Thanks, El Sid</p><p></p><p>FM:</p><p><img src="https://i.imgur.com/nHnrqzu.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>Whole circuit:</p><p><img src="https://i.imgur.com/wSFBK8Z.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p></blockquote><p></p>
[QUOTE="El Sid, post: 887627, member: 18550"] The FM is being problematic - either not working at all, or working for a short (but sometimes long) while, or one time even starting again after being dead. Often when I switch from AM to FM it is on for a few seconds then dies. While it is not working there is static, and it doesn't change if I turn the tuning dial. It certainly smells like an intermittent fault caused by something thing like poor contact, dry joint or dodgy components. The AM is working which suggests to me that the IF stages are fine. So far I have cleaned all the contacts on the 3 switches operated by the FM button, and taken the ECC85 out and cleaned its pins. Sometimes jiggling the ECC85 seems to help, but I'm not sure if it's coincidence. Next up I am going to trace out the circuit and check the components where I can, and see if I can get my hands on another ECC85. However, RF is not my forte (RF valve circuits even less so!) so I thought I'd ask the wise men out there if they have any suggestions. I've posted the circuit diagram for reference. As an aside, the switch diagrams are completely incomprehensible. Thanks, El Sid FM: [IMG]https://i.imgur.com/nHnrqzu.jpg[/IMG] Whole circuit: [IMG]https://i.imgur.com/wSFBK8Z.jpg[/IMG] [/QUOTE]
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DIY & Tutorials
DIY For Audio
Restoration of Philips B6X63A valve radio from 1956
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