pultec power supply problem

[buschfsu]

ok so ive read the posts about setting up the amveco 62082 even though they contradict. one post says to run the transformer 2 primary in series the other says parallel. and a third says run both in series on tx 2?????

my problem is this. when i wire in series i get 330V dc at 3.3K 2w resistor and it glows red hot.

when i wire in parallel i get 165v and it gets pretty dam hot also. i get about 19v on the tube side of the 3.3k resistor. transformer 1 is doing its job 6.1v out of the regulator and about 14.9 v out of the primary.

anyone have any idea what could be wrong?

http://www.groupdiy.com/index.php?t...ostorder=asc&highlight=amveco+pultec&start=15

first post shows parallel, second post describes serial????

 

[keefaz]

Depending on the used tube or the power of transformers, you may have to change the 3.3K 2w resistor

With a jan6922 in mine, I have to change it for a 5k 2w resistor, and I consider change it again for a greater value as I get 300VDC with the 5k

 

[ioaudio]

[quote author="buschfsu"]
when i wire in parallel i get 165v and it gets pretty dam hot also. i get about 19v on the tube side of the 3.3k resistor. [/quote]

something is wrong with your circuit if the 3,3k resistor drops 146 volt - be careful. did you install a bleeder resistor across the caps?

wiring wrong?

 

[buschfsu]

So it sounds like the diagram is wrong and i need to wire the primaires in series on TX 2 to get 250+ volts? (if i had thought about it it makes sense)

on to the other issues. Theres not much to mis-wire since its a pcb.
http://www.gyraf.dk/gy_pd/pultec/gy_pd.pdf

bridge recifiers + in the right place. polarity on the big electrolitics is correct. and since my heater voltage is correct im at a loss as to whats wrong. could i go up to 5k or more on the resistor to get down to 250 without it melting down?

tube is a national made in germany ec88 resistor melts down when the tube is in the socket.

HELP~

 

[keefaz]

[quote author="buschfsu"]...resistor melts down when the tube is in the socket...[/quote]
Which one? the 3.3k/2W ?
Are you sure there is not short somewhere ?

 

[ioaudio]

ec88 is not compatible. it´s not a twin triode, different pin-out - wrong tube.

 

[buschfsu]

WOOHHHH dam it is an EC88. (should be an ECC88) surprised that i didn't catch that.
so i went up to 5k without the tube in and its still sitting at 330V.

I will try a 10k 2 watt with the tube in and see

another question, can the bleed resistors be left across the HT caps permanently or should you only use them to bleed the caps?

 

[ioaudio]

leave them in. as soon as you charge the caps without a tube fitted they will keep the voltage forever. please be careful.
the pcb should be changed.



-max

 

[ioaudio]

without a tube fitted you cannot adjust the B+.

 

[ioaudio]

and stop abusing the ec88 already :shock:

 

[buschfsu]

ok guys thanks, maybe 5K is enougth then. i have an old Westinghouse ECC88 at the shop that ill try tonight. thanks!!

jason


max what do you mean the pcb should be changed? oh do you mean to add bleeder resistors permanently?
thanks