S.E.X.2.1 just completed but with some odd resistance reading...

[jamestw]

Just completed my S.E.X.2.1 last night and got some odd reading after through the resistance checking, I went back to check the wiring followed the manual step by step again, and push-pull all the solder joints by a pliers , but can not figure out where is wrong
Could someone please help me ...


TERMINAL      RESISTANCE    READING

center pin-input jacks, no matter volume set to min or max they show same resistances, (L)97KΩ , (R)94KΩ

1                       *                    *
2                       0Ω                  0.2Ω
3                       0Ω                  0.2Ω
4                       *                    *
5                       *                    *
6,16                   *                    *
7,17                   0Ω                  0.2Ω
8,18                   0Ω                  0.2Ω
9,19                   249kΩ             248.1Ω , 248.2Ω
10,20                  *                    *
11,21                  *                    *
12,22                 0Ω                  0.3Ω
13,23                 0Ω                  0.3Ω
14,24                 11.5KΩ            1.7Ω , 1.9Ω
15,25                 890Ω               893Ω , 890Ω
A1,B1                249kΩ              248.4KΩ , 248.5KΩ
A2,B2                *                     *
A3,B3                680Ω                684Ω , 681Ω
A4,B4                11.5KΩ             236.8Ω , 229.8Ω
A5,B5                *                      *
A6,B6                1.27KΩ             1.20KΩ , 1.20KΩ
A7,B7                174Ω                1.03KΩ , 1.03KΩ
A8,B8                 *                    1.03KΩ , 1.03KΩ
C1,C2,C4,C5        *                    1.03KΩ , 1.03KΩ


I did not fire it up for voltage check because these odd resistances.
Changed to the other pair of 6DN7 but the odd resis. reading still shown at same places.
I must have done something wrong somewhere, but just can not figure it out ...?.!

Thanks for helps.

james

[jamestw]

Oh I should mention, I skipped the headphone jack wiring, the OT-2 terminals 7 & 8 (for 8 ohm speakers) connect to speaker binding posts directly. But does this affect the resistance reading ?

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.bikedomeworks.tw%2Febay%2520images%2Fsex2.jpg&hash=0230e20f55fc7006b5047e0d3ff4416acb400ddb)


Thanks,
james

[jamestw]

After checked again and again each component position and joint, can not find out where is the problem, the resistance reading still same as before, I'm stuck...
Form the circuit scheme I can only guess the 1n5820 diodes or the 10000uf/10v cap might be damaged ?
Is it ok to do the voltage check ?

Thanks for help.
james

[Grainger49]

James,

The center pins should read 100k, you are right there, the position of the pot's wiper should make no difference.

Terminals A/B4 change with the position of the pot.

Terminals A/B7 are the heaters.  The other terminal is ground.  But for you to get a solid reading the tubes should be in.  Otherwise you are just charging the 10,000uF capacitor.  Did you measure with the tubes in?  

The only readings I can't suss out are the odd ones at T14/24.  Those are not the same points in the left and right circuits.

From the looks of it when you charge a capacitor you get 1.03k ohms.  That is probably a function of your meter.  Have you tried plugging in the tubes and turning it on?   First look for a glow from the heaters.

[jamestw]

Thanks Grainger,

Yes the resistance measurement all did with tubes in, as manual instruction. AHHH... you really inspired me, I have not checked without tubes in, just scratched my head and tried to find something wrong !!!
It is OK now, I decided to do voltage check anyway, kind of scary when the power on, because I did not know if this is safe, and prepared jump away if something wrong.

Turns out everything is good, tubes glowed up properly, went through all voltages are read good and close to list. The heater voltage is a little lower, A7/B7 and A8/B8 list is -3.15v and +3.15v, But I only get - & +3.025v. I think it's my place the main power only 155~116AC, not 120AC.

I'm listening SEX now, with Seduction, connect to JBL4425 speakers, very very VERY HAPPY ! quiet, clean, soundstage is wide, and, It just first operated within 1 hour... WOW


By the way, Congrats the " Grainger's Corner ", I have not go to read them yet, I will.
I'll go to play next record now...

Thanks again,
james

[Grainger49]

James,

It is always good to ask first before letting smoke out of something.

I just looked at the instructions and the schematic and saw that your readings were reasonable with what I know.

[Todd R]

Just got my SEX 2.1 running.
Had the same off resistance readings as jamestw so maybe these are mistakes in the manual?
I decided to fire mine up anyway since I was pretty confident I built it right (I think this is my 7th or 8th BH kit. Do Paramounts count as 2?)
Everything seems to be working fine.
Got it going head to head with a friend's original SEX amp with the C4S right now.
New amp sounds a lot like the old one, but is more detailed & quieter (very early impressions)

[Paul Joppa]

By "original SEX amp" do you mean version 2.0, or the ancient parallel-triode monoblocks?

[Todd R]

2.0