I have a HD-130 that i am trying to fix.
I have made some progress with the amp.
The amp has the SS phase inverter board.
After replacing 2 power tubes, I also found a faulty JE 1692 which i replaced with a MJE15030.
it has 4 good tested tubes and powers up
I cannot get any readings other than .1 volt on my bias probes.
I have adjusted the pot on the phase inverter board with no change.
my tubes are glowing.
There are 2 pots on the preamp board. Is the one towards middle for the tremolo?The one on the right side is near the *16v and -16v wires.
and there is a pot on the phase inverter board
Which pot is the one for adjusting tube bias? i am thinking the one on the phase inverter board is the bias pot?
Thanks I am familiar with tube circuits, when i saw the pot on the solid state phase inverter. it looks like the bias pot then im wondering if its a balance pot.
if the 1458 chip was bad. that would not affect the bias correct? i have checked many caps, diodes and resistors but i am unsure which pot adjusts bias. i thought that i would take a break and ask? and also what is that glass bulb for hooked to the mains fuse? is that a slow start? because when i first take out of standby my high voltage seems to take a few seconds to read.
every once in awhile i get varying high voltage but i am using a dim bulb and variac. Something is not right with the high voltage.my bias meter read over 1000 volts last time i powered it up. i adusted the variac back down
thanks for any info!
Bias Pot Location HD-130