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HELP ! My SSE voltages are way off.

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H

harry888

Disabled Account
Joined 2013
I'm doing my SSE checkout using Ty Bower's checkout routine.
With the amp unplugged all the resistances checks are spot on.
The problem is my voltage readings are way off.

Testing pins 4 and 5 in the 12at7 socket and pin 2 on the power tube
sockets I'm getting 7.15v instead of closer to the expected 6.3v

On the 5ar4 socket I'm getting 5.45v
The major issue is with pins 4 and 6 in the 5ar4 socket - I' getting
only 205v instead of the over 400v I should be seeing.

I wired it for basic triode operation with no CFB.
The choke is wired in but no auxiliary cap.

All my transformers are Edcors - XPWR035, CXSE25-8-5K opts and
CXC125-10H choke.
I fitted my board for both solid state and tube rectification but right
now I'm only using solid state.
I also have a CL90 on the switch side from the power input.

I'd appreciate any help from the forum. I've triple checked all
wiring connections and they look fine.
 
H

harry888

Disabled Account
Joined 2013
rknize said:
The voltages for the 6.3 and 5V windings are fine. They are within spec, given that the transformer has no load. As to the B+ voltage, it sounds like you don't have the secondary wired correctly.
Click to expand...


Okay, I did another check, here's my XPWR035-120 secondary connections -

5v yellow wires to T1-YEL terminals

6.3v brown wires to T1-GRN terminals

high voltage red wires to T1-red terminals, center terminal not used

black-red high voltage center tap to one of the T1-red-yel terminals

All the connections are tightly screwed down on the terminals.

Is it possible the high voltage windings could be faulty ? Can I test
this with a multimeter ?
 
Sodacose

Sodacose

Member
Joined 2006
Harry, did you check the solder connections on the terminal blocks for the B+? It could be that they're screwed down securely but lacking a good connection to the board itself.

edit: When you say it's wired for solid state and tube recto, and that you're only using solid state at the moment, do you mean the amp is working with solid state rectification?
 
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H

harry888

Disabled Account
Joined 2013
Sodacose said:
Harry, did you check the solder connections on the terminal blocks for the B+? It could be that they're screwed down securely but lacking a good connection to the board itself.

edit: When you say it's wired for solid state and tube recto, and that you're only using solid state at the moment, do you mean the amp is working with solid state rectification?
Click to expand...


I started to think about the solder connections and then I saw your post so
I checked and these look fine after a continuity check.

My board is the new one with the IN4007 diodes and CL140 inrush limiter.
All of these are in place. I did a check on the diodes and I get 590v forward
voltage.

Yes, it is on solid state rectification right now, I'll install the switch after I
get it working.
 
Sodacose

Sodacose

Member
Joined 2006
Did you also check the soldering on the recto tube pins? If your amp works with solid state rectification, I don't think there would be a problem with the transformer or block terminals. If you have an extra rectifier tube, I'd try that after checking the pins.


Edit: I don't have my board in front of me, but did you make sure to remove/isolate the solid state rectification from the circuit before trying a tube rectifier? That's otherwise the purpose of the switch and it sounds like you haven't installed that yet.
 
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H

harry888

Disabled Account
Joined 2013
Sodacose said:
Did you also check the soldering on the recto tube pins? If your amp works with solid state rectification, I don't think there would be a problem with the transformer or block terminals. If you have an extra rectifier tube, I'd try that after checking the pins.
Click to expand...

Actually I've just finished wiring up the amp. I'm doing initial checkout per
Ty Bower's checkout routine WITHOUT tubes installed. I'm trying to make
sure that my B+ is okay before I plug in the tubes and hook up speakers.
I did check all the tube pins when I populated the board but no harm
checking again.
 
Sodacose

Sodacose

Member
Joined 2006
Ok, I must have misread. I thought you had a working amplifier (SS) that you were trying to add tube rectification to.

Edit: Disregard message about removing the SS rectification. It looks like the board should be setup for tube rectification by default.
 
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H

harry888

Disabled Account
Joined 2013
Here's some more info.
As mentioned earlier I'm only getting 205v B+ on the 5ar4 pins.
I just checked the OPT's primary red connection but I get nothing here,
zero.
I also checked the choke connections and nothing here either, zero.
I was expecting at least some voltage here.
 
H

harry888

Disabled Account
Joined 2013
This problem have me really stumped.
I'd welcome anymore suggestions from you guys.

As I stated I'm getting only 205v B+ on pins 4 & 6 in the 5ar4 socket
using TY Bower's checkout routine.
Here's other things I've done in addition to what I described previously.

I checked voltage on the high voltage windings and it looks okay at around
385v each.
I removed the board to recheck all solder connections. I rechecked about
every connection on the board.

From T1-RED terminals to D1 & D2 - okay
from D1 & D2 to D3 & D4 - okay
from D3 & D4 to pins 4 & 6 in the 5ar4 socket - okay

I used the multimeter diode function to check D3 & D4 as well as
D1 & D2 and they all look okay.
The capacitors C1 and C2 look fine, no leakages or bulges.

Can you guys tell me any other things that I can checkout ?

Thanks.
 
S

Spoon109

Member
Joined 2011
H

harry888

Disabled Account
Joined 2013
Spoon109 said:
My voltage is 162 VAC at pins 4 and 6 in the 5ar4 socket.

However, with all the tubes in and the amp powered up, my B+ is 457 VDC.

You can find the rest of the checkout here in post# 5: http://www.diyaudio.com/forums/tubelab/158719-simple-se-checkout-dummies.html#post2051548

Its probably those 3 new parts added to the board. I think Ty documented his checkout procedure with an older version of the PCB board.
Click to expand...


Hi Spoon,

Thanks a lot for posting this, VERY helpful to know.

What power transformer are you using ? Mine is the Edcor XPWR035.

Now I can continue to rebolt my board to the chassis, rewire, recheck,
plugin my tubes and see what happens. I'll report back after this.

As I mentioned earlier my other voltages are within spec, confirmed by
Russ Knize. It is my low B+ voltages on pins 4 & 6 in the 5ar4 socket
that was holding me back.
I already read that thread you pointed me to, actually I've lost track of
the number of times I searched the forum for info related to my case.

Thanks again for your input.
 
H

harry888

Disabled Account
Joined 2013
Well, my SSE was fine all along, I got sidetracked by low B+ on the pins
in the 5ar4 socket.
After Spoon's post above I just plugged in the tubes, hooked up my speakers
and played music. It is playing well right now.

As Spoon suggested, maybe it is the 3 additional elements on the new
board that is causing the low B+ reading. I was following Ty Bower's
checkout procedure but he was using the original board for that.

Anyhow, thanks to all for their input.

P.S. - my amp has a nice smell right now, just like that fresh new smell
you get with new equipment. :)
 
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