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-   -   PT Help. (https://www.diyaudio.com/forums/tubelab/302978-pt-help.html)

Atk1d 29th January 2017 08:28 PM

PT Help.
 
Good Day everyone.
It has been awhile.

Ill get right into it.... I have an sse, the Pt is an edcore xwpr035-120
Primary 115 60hz
Sec. red/red 740v@200ma
Brown/brown 6.3v @ 5a (measured @7v)
yel/yel 5v @2a

The pcb has been tested using a different pt( 6k7vg) from Hammond, and the board worked quite well. Great sound, and loud.
after installing in new chassis with edcore Pt xwpr035-120,opt(cxse25-8-5k,and choke.

Ive no amplification??
volume pot is an alps 100k, and have to turn full to hear anything from spekers.
short of replacing PT with the Hammond, is there something else I can try?
some measurements below:

12at7 pins 4 and 9 measured 6.8-6.9v
rectifier tube(5au4) measured approx. 454v/
at choke connection 454v measured too.
across coupling caps, 454v left ch 99v at right channel. ( though upon inspection I may have right ch cap reversed)
driver tubes are 6l6
All tubes glow, though seem to run a little hotter then when used with 6k7vg


Thank you to all who reply

Atk1d 2nd February 2017 03:23 PM

Wow,I expected more from this community.
Not even one reply.

Thanks alot.
I'm out.

mkane77g 2nd February 2017 08:58 PM

Well hec. this is the second time I've viewed your post. I'm a Rookie and I can't help. Got to be something simple.

w5jag 2nd February 2017 09:06 PM

Quote:

Originally Posted by Atk1d (https://www.diyaudio.com/forums/tubelab/302978-pt-help-post4973626.html#post4973626)
Wow,I expected more from this community.
Not even one reply.

Thanks alot.
I'm out.

Why do you suspect the power transformer? I would check your input wiring.

Win W5JAG

PDL 3rd February 2017 01:24 PM

Quote:

Originally Posted by w5jag (https://www.diyaudio.com/forums/tubelab/302978-pt-help-post4973987.html#post4973987)
Why do you suspect the power transformer? I would check your input wiring.

Win W5JAG

+1

Can you send a picture of your wiring?

spendorite 3rd February 2017 01:50 PM

Quote:

Originally Posted by Atk1d (https://www.diyaudio.com/forums/tubelab/302978-pt-help-post4969114.html#post4969114)
Good Day everyone.
It has been awhile.


The pcb has been tested using a different pt( 6k7vg) from Hammond, and the board worked quite well. Great sound, and loud.
after installing in new chassis with edcore Pt xwpr035-120,opt(cxse25-8-5k,and choke.

Ive no amplification??
volume pot is an alps 100k, and have to turn full to hear anything from spekers.
short of replacing PT with the Hammond, is there something else I can try?
some measurements below:

Thank you to all who reply

It may be some kind of connection problem, maybe your input connection as suggested by W5JAG.
Also check all your grounding connections.

You say it worked fine when you had it bread boarded with the Hammond transformer but after you
assembled it in your chassis with the Edcor transformer you're getting the problem with no sound
output. This is why I suspect it is a connection problem.

If you cannot get it to work while assembled in the chassis, I know this would a major PITA but
disassemble it and bread board it again with the Hammond transformer then switch in the Edcor.
If it is okay then it is some kind of connection problem when assembled in the chassis.

I have the Edcor XPWR035 in my high voltage SSE and its ben working fine for 5 years.

w5jag 3rd February 2017 02:01 PM

This thread:

http://www.diyaudio.com/forums/tubel...stions-17.html

that is currently on the front page of the subforum, and has been for about nine months, has a good description of the troubleshooting process to resolve problems with input wiring.

Win W5JAG

Atk1d 3rd February 2017 03:44 PM

I will try that thanks. Will get back to you with results

spendorite 3rd February 2017 04:40 PM

Quote:

Originally Posted by Atk1d (https://www.diyaudio.com/forums/tubelab/302978-pt-help-post4974733.html#post4974733)
I will try that thanks. Will get back to you with results

If you haven't already done so, before doing doing anything else do as W5jag suggested, check your RCA input connections to
the board, If you're using a volume pot, check your connection to the pot then from the pot to the board.

Tubelab_com 3rd February 2017 10:04 PM

If the board was tested with am Allied 6K7VG and it worked, the board had been shown to work, so therefore, unless you have changed something, it was assembled correctly.

I am assuming that you mounted it in a chassis using the same OPT's, (or different OPT's?), but a different power transformer, and it doesn't work now.

Your voltage readings confirm that the power transformer is doing it's job. It can not be responsible for very low output. It and any external power supply (choke of aux cap) connections are properly wired.

If the board, transformers and other parts were assembled into a chassis and then the low output was discovered, the issue is likely with the wiring to the OPT's or input connectors.

The possible errors on the OPT wiring is a missing jumper or UL connection to the middle screw on the OPT primary connection, A ground wire connected to the wrong screw on the secondary connections. Speaker terminals that are not isolated from the metal chassis (both terminals shorted to the grounded metal chassis).

You should have a reading of over 400 volts on all three of each screws on the primary side of each OPT, and zero on each of the two secondary screws (negative meter lead on ground).

The usual culprit on the input side is a miswired volume pot, or reversed connections from the input connections to the pot or board.

Quote:

across coupling caps, 454v left ch 99v at right channel. ( though upon inspection I may have right ch cap reversed)
This reading isn't right. Measured to ground there should be from 100 to 200 volts on one end of each coupling cap, and zero volts on the other. Either way both channels should be similar (not necessarily identical).


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