Resistance Check Failure [solved]

[Doc B.]

If you find a cold joint it's often best to simply reflow the solder on every terminal. If you do this  before you spend a lot of time trying to analyze the exact location of every problem it can narrow things down.

[Paul Birkeland]

Yes, please proceed with the voltage check.

LED's not glowing on the 9 pin socket can be caused by several things, which we can help you work through.  There is this great temptation to try to reflow the solder holding the LED's in place, but this is almost always not the issue.

-PB

[Rhok]

Okay, I went with Doc's recommendation to reflow the solder on every terminal and I'm very confused with my voltage checks, something seems very off - and either I am not properly using the multimeter to test, or there is some major misconfiguration of  my crack. (wish I wasn't such an electronics noob, this experience will definitely make me want to learn/understand more - hate being clueless in a situation)

Anyways, here they are - or something' -

1: 2.0 m V AC

2: 1.1 m V AC

3: 1.0 m V AC 

4: 1.1 m V AC

5: 2.0 m V AC

6: 1.4 m V AC

7: 1.4 m V AC

8: 1.2 m V AC

9: 290 m V AC

10: 1.6 m V AC

11: 2.0 m V AC

12: 1.0 m V AC

13: 1.4 m V AC

14: 1.2 m V AC

15: 1.4 m V AC

20: 1.4 m V AC

21: 1.4 m V AC


A1: 2.7 m V AC

A2: 183 m V AC

A4: 14.6 m V AC

A5: 14.6 m V AC

A6: 175 m V AC

A7: 1.3 m V AC

A9: 6.15 m V AC

B1: 240 m V AC

B2: 1.4 m V AC

B3: 160 m V AC

B4: 140 m V AC

B5: 1.4 m V AC

B6: 1.4 m V AC

B7: 250 m V AC

B8: 240 m V AC

[galyons]

Reread pages 38 & 39 of the Crack assembly manual.  Your meter needs to be set for DC and if not auto-ranging, about 400volt range.  All of your voltage readings are VAC when they should  be VDC.   The only AC readings, (not in millivolts), should be the heater wires on the octal, (7 & 8 ) and 9-pin, (9, 4 & 5) sockets, (See pages 18 & 19 in manual).  All other voltages are DC.

Report back any DC voltages that are  more than 10-15% off the manual benchmark voltages.

Cheers,
Geary

[Doc B.]

Was anything lit up when you were measuring voltages - tube heaters or LEDS?

[Rhok]

Well I feel like an intelligent person - I will redo the readings on the correct multimeter settings when I get home.

And yes Doc, the tubes were glowing through the entire time - the LEDs were not.

[Rhok]

New results:

Max range set to 400

1: - 000.6 vDC

2: - 000.6 vDC

3: 0 vDC

4: - 000.6 vDC

5: - 000.6 vDC

6: 0 vDC

7: 0 vDC

8: 0 vDC

9: 0 vDC

10: 0 vDC

11: 0 vDC

12: 0 vDC

13: - 000.6 vDC

14: 0 vDC

15: - 000.6 vDC

20: 0 vDC

21: - 000.6 vDC

A1: - 000.6 vDC

A2: 0 vDC

A4: 0 vDC

A5: 0 vDC

A6: - 000.6 vDC

A7: 0 vDC

A9: 0 vDC

B1: - 000.6 vDC

B2: - 000.6 vDC

B3: 0 vDC

B4: - 000.6 vDC

B5: - 000.6 vDC

B6: 0 vDC

B7: 0 vDC

B8: 0 vDC

And on auto range:

1: - 0.679 vDC

2: - 0.680 vDC

3: 0 vDC

4: - 0.682 vDC

5: - 0.684 vDC

6: 0 vDC

7: 0.012 vDC

8: 0 vDC

9: 0.014 vDC

10: 0 vDC

11: 0 vDC

12: 0 vDC

13: - 0.665 vDC

14: 0 vDC

15: - 0.663 vDC

20: 0 vDC

21: - 0.661 vDC

A1: - 0.666 vDC

A2: 0 vDC

A4: 0 vDC

A5: 0 vDC

A6: - 0.665 vDC

A7: 0 vDC

A9: - 0.001 vDC

B1: - 0.664 vDC

B2: - 0.662 vDC

B3: 0.011 vDC

B4: - 0.663 vDC

B5: - 0.660 vDC

B6: 0.013 vDC

B7: 0.007 vDC

[Grainger49]

I guess I'll state the obvious, something is wrong.  If the tubes glow you should have about 6.3V AC on the heaters.  You have nothing anywhere.

I'll assume that your measuring method is the problem.  Voltage is read from one point to another.  And depending on the reference it can change.

Get some jumpers, wire with an alligator clip on each end, from Radio Shack.  Take a jumper and attach one end to the black lead of your meter.  Attach the other end to terminal 3 or one of the resistor leads that are soldered to terminal 3.  The resistor leads are easy to clip to.

Set your meter to AC volts and auto ranging, that is usually pretty good.  Turn on your Crack and carefully use the red lead to read the voltage at the small tube socket pin 4, then pin 9.  One of those should give a reading close to 6.3V AC.

[Rhok]

Hello Grainger,

Thanks for your input, this actually was how I was already making my readings - my multimeter has different leads, one of which is an alligator clip.

When measuring AC voltage, I do get readings - and when I switch to DC I get the readings I posted.

A4: 14.3 m V AC

A9: 06.14 V AC


I would definitely agree I am doing something wrong, or have the build wrong, but I am not quite sure of what that is. I'm really new to these kind of projects, and I really appreciate the provided assistance and patience with my situation.

[Doc B.]

OK, set your meter to AC volts at its highest range and measure the voltage across power transformer terminals 6 and 7, and then measure across power transformer terminals 9 and 10. These are the terminals right on the power transformer, not the strips mounted to the chassis. For each pair of terminals it doesn't matter which test lead goes to which terminal, as you are measuring AC volts. You should see roughly 150VAC across either pair. If that checks out OK we will proceed to the rectifiers.

[Grainger49]

Ok, those are good readings. 

Try this, put one meter lead on transformer terminal 9 and one on transformer terminal 10.  It is still AC.  It should be about 150V AC but will probably be higher since it doesn't seem to be turning on the tubes yet.

And I see I was too slow, someone else posted that already.

[Rhok]

Hello guys,

As requested.

Between 6-7 and between 9-10, I get the same reading which is 174.6 V AC

[Doc B.]

Ok, that's good. Now switch your meter to read DC volts on its highest range and measure the voltage at terminal 21. Touch the red test lead to 21 and the black lead to terminal 12 (which is power supply ground). You should see roughly 210 volts.

[Rhok]

My reading for this terminal is

21: - 0.665 V DC

Your instructions are about as simple as can be, so I don't think I'm measuring incorrectly, the value is just obviously way off.

Any ideas?

[Doc B.]

OK, either the rectifiers or the meter is not working. I would be grabbing a backup meter right now, but if you don't have one try measuring the voltage of a known good battery to verify that the meter will measure DC voltage properly.