Egnator Tweeker 88 power transformer

[Arbutt]

Hello all.
Sorry its me again.
I was asked to take a look at this egnator tweeker 88 which blew mains fuse at a gig. Customer loves to fix amps himself ,
Anyway when he got home he took the tubes out , still blowing mains fuse. He started removing all the connections to the power supply board. It stopped blowing mains fuse
At this point he didn't take any notes or pictures and boxed it up and dropped it in to me
I removed the power supply board and went over it no shorts or any issues found
I have changed D1-4 and C15 and C22 to be sure

When i looked at the diagram to see about re connecting the transformer and other connections thing too me didn't look right

Are there any errors on this diagram ?

QC13 ( 600V ) seems to go nowhere , I would of expected it to go to the CT of Power output tx ?? correct
But the diagram says the CT goes to QC18, this is saying then the KT88 are getting 300v on the anodes
Can that be correct ??

QC19 says its power ground (connected to chassis ) along with QC20 ( CT Heaters) and QC24 (Ground Bias)

Last thing
There is one further lead from power transformer which when checked out it reads to be CT of the
2 x red wires ( 470V AC) Not 100% sure if this should go to ground or not, when i do connect to QC19 the amp draws exxcessive current .
I have never had a bad power transformer that behaves in this way !!


I have changed D1-4 and C15 and C22 to be sure

Many thanks in advance for your input
Mr A

Egnater_Tweaker_88_Power.pdf

[Helmholtz]

With a bridge rectifier the HT winding CT (red/yellow?) must never be grounded.
Rather it should go to QC18. It's used for the 300V supply.
QC13 should go to the OT primary CT.
I don't think the PT is bad.

[Arbutt]

With a bridge rectifier the HT winding CT (red/yellow?) must never be grounded.
Rather it should go to QC18. It's used for the 300V supply.
QC13 should go to the OT primary CT.
I don't think the PT is bad.

Thanks Helmholtz . The HT -CT from the power tx is black. . I'll have to see tomorrow what the hell is going on .thanks again .

[Arbutt]

Thanks Helmholtz
It has cured that issue. Now Im not sure why the amp was appartly blowing Mains fuse.
But its powering up now , still not working, Just got to find that problem.
Thanks again for your input
Mr A