04-18-2013, 09:17 AM
Jeff
We will help you with concrete questions and troubleshooting once you get to that.
But first things first, please read through the very basic things one does when starting with an old radio.
That means:
1. No powering up before checking the state of the chassis. Big NO-NO!!!
2. No powering up before changing all electrolytic caps and all the caps that are from B+ to Chassis.
3. Very desirable - changing ALL paper caps. Leave micas alone for the time being.
4. Remove the rectifier tube, measure the load resistance to see if a short is present.
5. Check ALL tubes, so they at least present no danger and could be expected to work reasonably (even if weak) - no shorts or other BAD stuff.
6. At this point if you feel an itch, bring the transformer slowly up by using variac, measure the voltages, see if the output is reasonable and no smoke escapes.
7. Check all the resistors, replace those that are way out of spec (20% and more) or open. Make sure your wire-wound ones are not open, especially the one that connects the negative of the rectifier to the chassis. Sometimes those are Candohms and those are know to open.
8. Replace the rectifier and the tubes, then you can power it now, but ONLY slow using a variac and (very desirable, but absolutely necessary with "hot chassis'") isolation transformer. While bringing the voltage up, do the reading, making sure there are no load shorts / problems.
Now if all holds, nothing smokes and all glows, you can start troubleshooting.
That is where we come in.
We will help you with concrete questions and troubleshooting once you get to that.
But first things first, please read through the very basic things one does when starting with an old radio.
That means:
1. No powering up before checking the state of the chassis. Big NO-NO!!!
2. No powering up before changing all electrolytic caps and all the caps that are from B+ to Chassis.
3. Very desirable - changing ALL paper caps. Leave micas alone for the time being.
4. Remove the rectifier tube, measure the load resistance to see if a short is present.
5. Check ALL tubes, so they at least present no danger and could be expected to work reasonably (even if weak) - no shorts or other BAD stuff.
6. At this point if you feel an itch, bring the transformer slowly up by using variac, measure the voltages, see if the output is reasonable and no smoke escapes.
7. Check all the resistors, replace those that are way out of spec (20% and more) or open. Make sure your wire-wound ones are not open, especially the one that connects the negative of the rectifier to the chassis. Sometimes those are Candohms and those are know to open.
8. Replace the rectifier and the tubes, then you can power it now, but ONLY slow using a variac and (very desirable, but absolutely necessary with "hot chassis'") isolation transformer. While bringing the voltage up, do the reading, making sure there are no load shorts / problems.
Now if all holds, nothing smokes and all glows, you can start troubleshooting.
That is where we come in.
