voltages on V3 (18 watt classic tremolo)
Posted: Fri 03/06/20 7:02 am
hey guys
I just' can't figure out why the voltages on my tremolo tube are so off..
I just can't see anything wrong on the wiring, components,... the soldering is ok and the chopstick method gives me zero hunches.
voltages measured:
B+ after the rectifier (diode 1N4007 types + 220ohm 10W resistor) = 360V (pretty high, but no real danger?)
V1: p1 158V / p3 1.18V / p6 158V / p8 1.18V
V2: p1 223V / p2 51.3V / p3 68V : p6 225V / p7 51.2V / p8 68V
V3: p1 188V / p3 1.49V / p6 128V / p8 1.49V
V4: p3 12.96V / p7 345V / p9 340V
V5: p3 12.95V / p7 345V / p9 340V
HV1 and 2: 294V
Heaters: 2.9V both
you see that the values for V3 are pretty weird.
- I thought p1 and 6 should differ in opposite direction (p1 should be lower in voltage than p6)
--> what's the 110/150 spec value on the chart stand for? why 2 numbers? trem oscillation values?
- the cathode values are nearly 40% higher than spec'd. What could cause that?
What is the best way to lower the B+? zener diodes in the B+ line or higher cathode resistor value? (have 180 ohms in there already, plus a 2200uf/50V cap)
I also read somewhere that the 100 ohm screen resitor cap upped to 1k or higher also helps?
I really need some advice on the V3 values!!! please...
the amp hisses somewhat more than normal, but my guess it's the higher B+ that's causing this..makes the amp hotter after all
I just' can't figure out why the voltages on my tremolo tube are so off..
I just can't see anything wrong on the wiring, components,... the soldering is ok and the chopstick method gives me zero hunches.
voltages measured:
B+ after the rectifier (diode 1N4007 types + 220ohm 10W resistor) = 360V (pretty high, but no real danger?)
V1: p1 158V / p3 1.18V / p6 158V / p8 1.18V
V2: p1 223V / p2 51.3V / p3 68V : p6 225V / p7 51.2V / p8 68V
V3: p1 188V / p3 1.49V / p6 128V / p8 1.49V
V4: p3 12.96V / p7 345V / p9 340V
V5: p3 12.95V / p7 345V / p9 340V
HV1 and 2: 294V
Heaters: 2.9V both
you see that the values for V3 are pretty weird.
- I thought p1 and 6 should differ in opposite direction (p1 should be lower in voltage than p6)
--> what's the 110/150 spec value on the chart stand for? why 2 numbers? trem oscillation values?
- the cathode values are nearly 40% higher than spec'd. What could cause that?
What is the best way to lower the B+? zener diodes in the B+ line or higher cathode resistor value? (have 180 ohms in there already, plus a 2200uf/50V cap)
I also read somewhere that the 100 ohm screen resitor cap upped to 1k or higher also helps?
I really need some advice on the V3 values!!! please...
the amp hisses somewhat more than normal, but my guess it's the higher B+ that's causing this..makes the amp hotter after all