03-05-2011, 10:31 AM
Hi
The steady buzz is usually caused by bad electrolytics, but you say you have replaced them. Could you have installed them backwards? (It happens, even to us old timers occasionally.)
Do you have the schematic/service data? If not...this is something you must have, especially as a beginner. Contact Chuck for the best possible copy of this data.
http://www.philcorepairbench.com/schematics.htm
It can be difficult, and sometimes impossible, to tell what type a tube is if the numbers are gone. Try this: Rub the top of each tube on top of your head; the oils in your hair can sometimes make the numbers visible enough to be read under bright light. If you're bald, forget this trick.
Incorrect tubes in sockets can wreak havoc with the circuitry, but you shouldn't have 170 volts DC at the speaker, not even at the field coil wires. The field drops 25 volts across it, and an additional 5 volts is dropped across the audio output transformer primary.
Be careful! That is an AC/DC set (transformerless); you could be electrocuted if you do not know what you are doing! Of course, you could be electrocuted when working on a set that uses a power transformer; but in an AC/DC set, there is no isolation from the AC line so the danger of shock is even greater.
The steady buzz is usually caused by bad electrolytics, but you say you have replaced them. Could you have installed them backwards? (It happens, even to us old timers occasionally.)
Do you have the schematic/service data? If not...this is something you must have, especially as a beginner. Contact Chuck for the best possible copy of this data.
http://www.philcorepairbench.com/schematics.htm
It can be difficult, and sometimes impossible, to tell what type a tube is if the numbers are gone. Try this: Rub the top of each tube on top of your head; the oils in your hair can sometimes make the numbers visible enough to be read under bright light. If you're bald, forget this trick.
Incorrect tubes in sockets can wreak havoc with the circuitry, but you shouldn't have 170 volts DC at the speaker, not even at the field coil wires. The field drops 25 volts across it, and an additional 5 volts is dropped across the audio output transformer primary.
Be careful! That is an AC/DC set (transformerless); you could be electrocuted if you do not know what you are doing! Of course, you could be electrocuted when working on a set that uses a power transformer; but in an AC/DC set, there is no isolation from the AC line so the danger of shock is even greater.
--
Ron Ramirez
Ferdinand IN
