Peavey 5150 II Plate voltage too high?!

[theholyweed]

Hi all,

A friend of mine dropped in a 5150 mkii to get re-tubed so I had it on the bench the other day and checked the plate voltage and I got a reading of 570v without the valves (just a tad over 555v with tubes in).. This seems pretty high, from what I understand it should be around 500v... iv given the amp a quick check over and everything else seems ok..I checked the PT and it seems higher than the values I found online at the thetubedoctor.com for their replacement PT...the replacements listed online specs are:

Secondary:
350V@0.4A Red
0V Red
52V@0.1A Violet
0V Violet
18V@0.9A Orange
0V Green/Yellow
18V Orange
6,3V@6A Yellow
0V Yellow


My Secondary is coming in at:

405v Red
20v Orange
60v Violet
5/6v Yellow


Would this explain the high plate voltage or am I missing something here and being a twat?

Any help would be extremely appreciated!

[nosaj]

What is your bias current? That should tell you more as to how your voltage lines up.

nosaj

[Gregg]

5150's plate voltages are usually in the 500V region, could be 520 but 555V is definitely high. I would check if tubes are pulling current at all and then check how the PT primaries are connected in case it has multiple primaries of course.

[g1]

What is your line voltage and what line voltage is the amp set up for? What is the heater voltage?