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Audio and Video Talk
Valves / Vacuum Tubes
Leak Stereo 20 restoration/mods
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<blockquote data-quote="charles" data-source="post: 573366" data-attributes="member: 2759"><p>Jonathan,</p><p></p><p>The first valve amplifier I restored was a ST20.</p><p></p><p>Keep the reservoir capacitors in their cans and just remove the wiring from it. Replace it with modern electrolytic ones. These are very small ones and will fit under the chassis.</p><p></p><p>Like valvesound said, replace all the coupling capacitors, except the one in the feedback loop (very low value). Check the resistors and replace the ones that drifted out of specification. I usually do not replace all the old resistors.</p><p></p><p>Keep the old components.</p><p></p><p>Do not change (modify) the circuit topology of the amplifier.</p><p></p><p>Do not drill any holes into the chassis.</p><p></p><p>Keep it as original as possible.</p><p></p><p>If possible, test the valves with a valve tester to determine the emission/mutual conductance of the valves.</p></blockquote><p></p>
[QUOTE="charles, post: 573366, member: 2759"] Jonathan, The first valve amplifier I restored was a ST20. Keep the reservoir capacitors in their cans and just remove the wiring from it. Replace it with modern electrolytic ones. These are very small ones and will fit under the chassis. Like valvesound said, replace all the coupling capacitors, except the one in the feedback loop (very low value). Check the resistors and replace the ones that drifted out of specification. I usually do not replace all the old resistors. Keep the old components. Do not change (modify) the circuit topology of the amplifier. Do not drill any holes into the chassis. Keep it as original as possible. If possible, test the valves with a valve tester to determine the emission/mutual conductance of the valves. [/QUOTE]
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Audio and Video Talk
Valves / Vacuum Tubes
Leak Stereo 20 restoration/mods
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