Resistance Check help [SOLVED]

[Thebb]

OK.  So I finished my crack build today and I thought I'd be listening to some music (right...) lol

I have checked and double checked that all wires and components are where they need to be, but somehow I have managed to build some sort of Frankenstein.  Hopefully, there is an wasy fix to this.

Also, I found out today that the volt-ohm meter I have (Fluke 323) only measures up to 4k Ohms.  So measuring the * gave no readings.

I had to measure them with the ground next to the IEC fuse holder cause 12 was not working at all for me. 

Here are my measurements:

Terminal    Manual          Thebb

1                  *                NO READING
2                  *                NO READING
3                  0 ohms      OK
4                  *                NO READING
5                  *                NO READING
6                  2.4k ohms  NO READING
7                  2.9k ohms  OK
8                  0 ohms        OK
9                  2.9k ohms  OK
10                2.4k ohms  NO READING
12                0 ohms        NO READING
13                *                NO READING
14                0 ohms        NO READING
20                0 ohms        NO READING
22                0 ohms        OK
B3                2.9k ohms  OK
B6                2.9k ohms  OK

RCA jacks:
Ground Lug  0 ohms        OK
Center pin (where is the RCA jack center pin)? if this is supposed to be 9 socket center pin I got a 0 ohms reading

 

[Paul Birkeland]

A Fluke 323 is a clamp meter.  It's a very odd choice for this kind of work.  If you have a Harbor Freight near by, you can get an acceptable meter for under $5.

It would probably be best to get a meter more suited for the task before proceeding, or borrow one from a friend.

With that out of the way, you aren't getting a reading at terminal 12, and that's a problem.  There is black wire from terminal 12 to terminal 3, so either a wire is missing or it isn't soldered properly.  This most often happens at the headphone jack.

If you are wondering if a wire is well soldered, try pulling it out with pliers.  If it's well soldered, it won't come out.  If it's not well soldered, it will slide right out of the joint.  (note that adding more solder isn't the solution, but rather taking half a wrap around the terminal to make a mechanical connection)


-PB

 

[Grainger49]

I have a Fluke 87.  It is great!  Every 3-4 years it gives some odd readings, I change the battery and everything is good for years.

 

[Thebb]

I borrowed the Fluke 323 from my father in law.  I will get a new multimeter today and report back with the readings.

Regarding the wire from terminal 12 to 3.. I don't have a direct wire for that.  Is there supposed to be one? 

I do have 12L>Headphone jack>Potentiometer>3L.  Is that what PB means? None of the wires move when tugged, so they seem to be soldered.

 

[Grainger49]

Try these measurements:

http://bottlehead.com/smf/index.php?topic=4812.0

 

[Paul Birkeland]

12 wires to headphone jack ground, headphone jack ground wires to pot ground, pot ground wires to T3.

A solid wire connection should provide a very low impedance path.

-PB

 

[Thebb]

So, after tracing the ground signal which Grainger suggested, I was getting no measurements on the headphone jack.  As suspected by PB.

I desoldered the headphone jack, tightened the wire hook to the terminal and resoldered.  Seems like that was it.

Terminal  Measurement

1            ~115k
2            ~130k
3            0 ohms
4            ~100k
5            ~93k
6              2.57k
7              2.93k
8              0 ohms
9              2.9k
10            2.54k
12            0 ohms
13            OK
14            0 ohms
20            0 ohms
22            0 ohms
B3            2.8k
B6            2.9k

RCA:
Ground lug 0 ohms

After some poking around I assume that the "RCA jacks center Pin" measurement is actually the Potentiometer center pins.  Which measured within range. Please correct me if I am wrong and if I should not continue with the voltage check.

Also, the voltage check suggests I connect it to Terminal 12 for ground.  With the capacitor, resistor and a wire in there it is a bit uncomfortable.  Would it be ok if I used terminal 11 which is completely free?
Thanks!

 

[Paul Birkeland]

After some poking around I assume that the "RCA jacks center Pin" measurement is actually the Potentiometer center pins.  Which measured within range. Please correct me if I am wrong and if I should not continue with the voltage check.

Each RCA jack has a shell (which the black wire connects to) and the center pin (the red and white wires go here).  None of these are equivalent to the center lugs of the potentiometer unless the potentiometer is turned up all the way.

-PB

 

[Thebb]

Got it.  I will recheck that part when I get gome.

I dont know if you read the last part of my post as I was editing right as you responded:

Also, the voltage check suggests I connect it to Terminal 12 for ground.  With the capacitor, resistor and a wire in there it is a bit uncomfortable.  Would it be ok if I used terminal 11 which is completely free?

 

[Paul Birkeland]

I personally like using the solder lug at the #8 screw back by the power entry socket.

-PB

 

[Thebb]

Perfect.  That was also my other option.  Thanks again for the troubleshooting help.

 

[Thebb]

Finally passed the resistance check, passed voltage checks, tubes glowing nicely.  Connected everything... No sound.. Just a very light buzz in the background that does not get louder with turning the volume up.  Tried two different RCA cables.

 

[Paul Birkeland]

How are the resistance measurements across the RCA jacks with the volume control turned all the way up?

 

[Thebb]

After I posted on the no sound issue, I poked around a bit, resoldered here and there and seems to have fixed that issue. 

What I am experiencing now I am not sure if it is a problem or not, but I have read of people here who listen at 20% volume and that seems to be loud enough.  20% volume for me is barely listenable.  I have to pump the volume up past 60-70 person to have a good listening session.  For other cracks I;ve read about, that an unlistenable level.  Even on my FiiO E12, which is puny compared to the crack, I wouldn't go past 40=60% volume.

I rechecked the voltages and everything is perfectly within range.

Does this seem like an issue to you?

NOTE: I isntalled a VALAB 23 step potentiometer, so I don't know if this would change that. And answering your original question, at full volume, resistance at center pins is still around 100k.

 

[Doc B]

This is all very dependent upon the source and the headphones used. If you can turn it up to a point where it is too loud, you have plenty of range adjustment.

 

[Thebb]

Great.  I think this thread can be marked as SOLVED.  Thanks for all the help.  Been enjoying my crack the past few days.. Will be ordering the speedball soon enough.