test 1 step E - low voltage on rectifier + terminal

[banghoyt]

Hey guys,
I'm new to the forum and I just started testing part one on my second build, a Plexi bass 1986. My AC at the hot side of the power switch is 120, the heaters on all tubes are reading 3.0 ac and the bias is right on both power tubes (41 currently). I hit a snag on step E. When I measure the + side of the rectifier (standby off) it is reading 300v instead of 350. What would cause a low voltage reading on the rectifier + terminal?

Also, just out of curiosity, I flipped the standby on and there was no voltage jump.

Thanks ahead of time for the help. This forum is a huge help.

[neikeel]

First welcome!

Second 3vac is slightly low. This may be borne out when your ac from the rectifier is also a little low.

What do you get at the apex of your rectifier (assuming no tubes)?

Suggest you post the whole results of your voltage charts with tubes out.

Things to check are your wall voltage and which taps you are using on your PT (that is basically where your heaters come out),

ie if you have a 120vac wall voltage and use the 120vac tap your heaters should sit at approx 3.15vac.

[banghoyt]

Thanks for the help neikeel.

While I was waiting I remembered that I had found that switch in a box of old parts so I pulled it out and put in a new one. Voltages are normal now so I am on to Testing Part Two. Thanks again!