Eros2 Bad Voltage Check

[Moodyhh]

Hello All,

After installing the shunt regulator board the voltage check result was 284.5 volts
at the outer terminals of both MJE5731A transistors.  The manual calls for
between 210 and 230 volts…
Any ideas?

Thanks,
Moodyhh

[Paul Birkeland]

What are your Kreg voltages? Does the 12AU7 glow in that socket?

[Moodyhh]

Thanks Paul.  I’ll check these shortly.  When the 12AU7 is inserted,
should it go all the way down to the base - it seems to only go until
5mm and then stops?

[Moodyhh]

Ok - I checked the voltages at KREG - “A” side is 2.4 and “B” side is 2.1 volts.
BTW - The voltages at the MJE5731A(s) are now 281.

Thanks,
Moodyhh

[Larpy]

Thanks Paul.  I’ll check these shortly.  When the 12AU7 is inserted,
should it go all the way down to the base - it seems to only go until
5mm and then stops?

Tubes should seat completely in the socket.  You might have used too much solder on one of the tube socket connections and it flowed down the connector, blocking the pin from seating.

Do you have a solder sucker/vacuum pump?  If so, find which of the tube connectors is blocked and suck out the solder, then resolder the connection making sure you don't use too much.

[Moodyhh]

I just used a piece of solid wire to check the depth of all the pin receptacles - none are blocked,
however, some have more spring than others.
I’ve heard of some people having to use a lubricant on the pins in order to get the tube to seat.

BTW, the 12AU7 does seat a little better now (after some work), and it does glow.
The other tubes in the other receptacles aren’t seating any better.
The two large resistors in the center of the shunt board seem to be getting
pretty hot.

Thanks,
Moodyhh

[Paul Birkeland]

Can you post some build photos?  I would be extremely interested in seeing the bottom of the C4S board that you are testing.

[Moodyhh]

Hi Paul,

This reading error was all my fault.
When the manual said check to place the positive
probe on to the metal tab, I placed the probe on one of
the terminals.  The readings after 5 minutes are as follows:
Side “A” is 216.1 and Side “B” is 216.7 volts

So all seems fine now - sorry about that!

BTW, is it normal that the board will generate a little heat, and have that
electronics smell? Thanks, Moodyhh

[Paul Birkeland]

Heat is normal.  If things were getting too hot, you'd see voltages that are lower than they should be.  Just to be sure, you should measure about 275V coming out of the rear power supply board high voltage terminal now.