New Crack build - question right off the bat [resolved]

Mr. Electric Wizard · 3497

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Offline Mr. Electric Wizard

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Reply #15 on: April 17, 2020, 04:25:24 AM
did you check the fuse for continuity with an Ohm meter?
You need to install the fuse in the clips of the PEM cover. If you place the fuse in the enclosed tunnel it will not work, that space is to store a spare fuse.

Yep, i checked fuse continuity with my DMM (i used the beeping function) and there is no continuity.
And yes, the fused is installed in the clip (not the tunnel).  I even tried to install the fuse into the clips directly (without the cover installed) and still no voltage.
So, I'd say the fuse is bad.



Offline Mr. Electric Wizard

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Reply #16 on: April 22, 2020, 04:15:00 AM
Well, I got the new fuses in the mail and built the rest of the Crack!
Now that it's built, I'm on the part where I am checking resistance values. 
Some of the values didn't match but I think there might be something wrong with my DMM though. 
Some of the digits looks like parts of the liquid crystal display are dead, so I ordered a new one.
Crossing my fingers that everything is hooked up correctly.
When I do the resistance checks again and see some differing values, I'll post some pictures.

The manual shows examples of bad solder joints.
I'm pretty sure some of my joints have too much solder, but hopefully they don't mess up my resistance values.
Will go through the resistance checks again when I get my new DMM.
I did double check the wiring based on the completed photo in the manual and everything looks like it's hooked up correctly.
I was VERY careful making sure that each part was connected as per the manual.



Deke609

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Reply #17 on: April 22, 2020, 05:52:41 AM
You could try fresh batteries in your existing meter. Weak batteries can produce weird readings.

cheers, Derek



Offline Mr. Electric Wizard

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Reply #18 on: April 22, 2020, 05:59:15 AM
Here's some photos of my [poor] execution of the kit if anybody cares to look and tell me if anything looks amiss.
My incoming line voltage is 122V.
Thanks!



Offline Mr. Electric Wizard

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Reply #19 on: April 22, 2020, 06:00:13 AM
You could try fresh batteries in your existing meter. Weak batteries can produce weird readings.

cheers, Derek

Used the batteries that came with the DMM, but I guess that doesn't mean that they're necessarily good.
Will try some different "new" ones.
Thanks for the suggestion.




Offline Paul Birkeland

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Reply #20 on: April 22, 2020, 06:02:11 AM
If your soldering iron has a heat adjustment, I would turn it up as high as it would go and reflow a fair number of the joints.  In particular, B7/B8 look like they could use some extra heat, as do some of the joints where the UF4007s mount.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Mr. Electric Wizard

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Reply #21 on: April 22, 2020, 07:56:20 AM
If your soldering iron has a heat adjustment, I would turn it up as high as it would go and reflow a fair number of the joints.  In particular, B7/B8 look like they could use some extra heat, as do some of the joints where the UF4007s mount.

Thanks for much for taking the time to look at my wiring.
I went ahead and reflowed all the joints.  Will check resistance again when my new DMM shows up (the new batteries yielded the same LCD issues).

One more question though:  When resistance is checked the black lead on the DMM is supposed to be connected the ground bus, is that the 12U on the terminal strip?  It seems like a better place to put the black lead is on the chassis ground?  I guess my more pointed question is the 12U tab the ground bus?



Offline Mr. Electric Wizard

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Reply #22 on: April 22, 2020, 09:27:56 AM
So here's my preliminary resistance numbers.
I hope I didn't screw the pooch when it cam to putting the kit together.
These don't loo

1.  * - mine -> infinity
2.  * - mine -> infinity
3.  0  - mine -> 0
4.  * - mine -> infinity
5.  * - mine -> infinity

6.    0 - mine -> 2.49
7.    2.9 - mine -> 2.92
8.    0 - mine -> 0
9.    2.9 - mine -> 2.93
10.  0 - mine -> 2.48

12.  0 - mine -> 0
13.  * - mine -> 0
14.  0 - mine -> 0

20.  0 - mine -> 0
22.  0 - mine -> 0

B3 2.9 - mine -> 2.92
B6 2.9 - mine -> 2.93

RCA Jacks
Center Pin 90-115 - mine -> infinity
Ground tab 0 - mine -> 0

Some of these seem way off.  This is with the old multi-meter.  I can get a the digit before the decimal point to show if I put some pressure on the LCD with my screen.  Also, I am using the 20K range on the Ohm meter.  And lastly, the alligator clips are the press in kind that fit over the top of the pointy lead (which may just be a bad connection).
When I say infinity, it's the reading that you get when the red lead is not connected to anything.



Offline Paul Birkeland

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Reply #23 on: April 22, 2020, 09:59:32 AM
Can you post some photos of your build?  Specifically I am very interested in the wiring around your headphone jack.

Absolutely to not attempt to power up this Crack just yet.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Mr. Electric Wizard

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Reply #24 on: April 22, 2020, 10:15:43 AM
Hey absolutely Paul!  I am actually scared to apply power to it, especially until I get my new DMM.
Here's a photo.  Let me know if it's not good enough and I will try to get a better one.



Offline Mr. Electric Wizard

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Reply #25 on: April 22, 2020, 10:16:42 AM
Wow that photo shows how terrible my solder joints actually are.
Whoa  :o



Offline Paul Birkeland

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Reply #26 on: April 22, 2020, 10:42:57 AM
Can you check the DC resistance between terminal 12 and all the lugs on the headphone jack?  Also, you didn't have anything plugged into the 1/4" jack when you did your resistance measurements, right?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Mr. Electric Wizard

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Reply #27 on: April 22, 2020, 10:58:05 AM
Doh!  I did have a 1/4" to 1/8" adapter plugged in.  I forgot it was there.
After removing the adapter, all looks good except for the center pins of the RCA's.
Both are showing infinity.



Offline Mr. Electric Wizard

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Reply #28 on: April 22, 2020, 11:22:03 AM
Wait, when I change the scale on the DMM to 200K (all other measures were done with the 2K scale) I get 98K on both RCA barrels.
You think i'm good?



Offline Doc B.

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Reply #29 on: April 22, 2020, 11:40:04 AM
Yup.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.