PT HV is high

[trem]

Working on a friends Silvertone 1421...his is a Sears 10 XL i believe.?
I pulled the can cap and installed 3 radials, cleaned up the heater wring...checked everything out.
It came to me with a 3 wire plug, but the cord was only 2 wire. The first power supply dropping resistor was black, you could not see any of the color rings.
I actually pulled the PT from the chassis, and carefully applied 120 VAC to the primary. The heaters were fine...just about 7.2 V.
I thought the HV was a bit "low", it was 220V. I should have...wished i had, double checked my clips on my DMM, but it seemed like the PT was more or less functioning normally, so i kept going.
I wire everything back up, there are no shorts, heaters drop to a normal 6. something or other.....but the HV reads 648 VAC.!
I pulled the rectifier tube, and it reads the same at the socket. I lifted one side of the HV (from the rect socket) and it still reads (this is a few days later now) 640 VAC.
Did i not have a good connection at my meter when it read 220 VAC.?
Have i wired something fundamentally wrong.?
Could the PT have somehow (partially) failed, and is now reading 400 volts higher.?
I am not sure what to do at this point.
Thank You

http://el34world.com/charts/Schemati...rtone_1421.pdf

[nickb]

It sounds like you connected one end of the primary to ground and left the CT either floating or connected to the rectifier (in which case it won't be doing anything). I wonder if your new caps might be damaged with so much excess voltage applied.

[trem]

The HV CT is grounded. The two Red wires of the HV are connected to.......1 and 6.
FWIW.....i believe the heaters are wrong on that schem. I think they are 3&4 not 4&5.

[Justin Thomas]

Meter battery?

Justin

[trem]

The heaters seemed fine and so does the 120 at the wall.....but going to try that now...always forget that. Thanks.

[mozz]

With all tubes plugged in what are your heaters at? 6.3? 7.0? What is the high voltage? Maybe wire in a 6ax5?

[trem]

The old battery was 8.75...new battery is 9.4...but no change to the high HV.
Yeah, my heaters dropped down to normal with the tubes in.

[nickb]

Transformers don't develop extra turns, of that we can be sure. If you had a short on the primary of that magnitude you'd be blowing the fuse.

Remeasure from one HT red wire end to CT and then to the other red wire and tell us what you see. For sanity, check the line voltage before and after to be sure your meter is OK. Do you have another meter to confirm your measurements?

[Dave H]

I wire everything back up, there are no shorts, heaters drop to a normal 6. something or other.....but the HV reads 648 VAC.!
I pulled the rectifier tube, and it reads the same at the socket. I lifted one side of the HV (from the rect socket) and it still reads (this is a few days later now) 640 VAC.

I can't follow your description. The HV reads 640 VAC measured between which two points? If you are measuring between the plates of the rectifier (pins 1 and 6 on the schematic) then 640 VAC unloaded may be OK. The PT could measure 320V 0 320V unloaded.

[mozz]

"Heaters dropped down to normal" Tell us the voltage 6.3? 7.0? What is the plate voltage with all tubes plugged in? Are you using a old real 7189? They can handle more voltage than the new one marked "7189 or el84" I don't think i ever measure the ac hi-voltage.

[trem]

Yes...you are absolutely right.....sorry.
I am an idiot.....I am looking at an old schem, that came with the amp, and is hard to read...does not even show a CT. If i would have bothered to look at the schem i linked to, for your guys help, i would have seen that. Just looking at it now. I better recheck everything against this much better print on the screen.
My Apologies.
Well, i was right, i was doing something fundamentally wrong. Sorry Again.

I would be happier if you guys were to just gang up and make fun of me.
The silent treatment is worse.