Resistance Check Failure [solved]

Rhok · 6328

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Offline Rhok

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Reply #30 on: April 11, 2014, 05:37:58 PM
Hmm, I grabbed a AAA rechargable battery and got a 1.321  V DC reading, so that would indicate that it should be reading DC voltage properly, what now?



Offline Doc B.

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Reply #31 on: April 11, 2014, 07:06:12 PM
OK, this is a bit of a pain, but try disconnecting the 270 ohm resistor and the positive terminal of the 220 uF capacitor from terminal 21 and then measure the DC voltage at terminal 21 the same way as before, red to 21, black to 12. That will help determine if the rectifiers are bad, or if they are working Ok and there is a short to ground in the circuit somewhere after the rectifiers.

By the way, I have had meters that worked OK on lower scales but didn't work on the highest voltage scale. If you had it set to a lower scale when you checked the battery you might want to measure that battery one more time on the 400V scale. It won't be as accurate, but you should see at least 1V.

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


Offline Grainger49

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Reply #32 on: April 12, 2014, 04:44:31 AM
How about posting a picture of the right and left sides of the terminal strip where the diodes are.  We want to verify that the diodes are oriented properly.



Offline Rhok

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Reply #33 on: April 12, 2014, 05:24:07 AM
Doc, I will attempt your recommendation after Grainger reviews my pictures, additionally, while having my multimeter set to 400 range, testing the same battery yielded these results: 001.3 V DC.

Grainger, here are the pictures you requested: http://i752.photobucket.com/albums/xx165/mikemathis3/IMG_0719_zps273125bf.jpg & http://i752.photobucket.com/albums/xx165/mikemathis3/IMG_0718_zps0b94f959.jpg



Offline Grainger49

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Reply #34 on: April 12, 2014, 05:40:03 AM
They are all correct.  I also see the caps are oriented properly. 

I'm with Dan, try reading the DC as he says and then directly.  Try measuring DC from (always the black lead) terminal 21 to (always the red lead) terminal 20. 

Also, I'm not positive that the AC feed is solid.  Try measuring from terminal 18 to terminal 19. 

Your transformer seems to work properly.  The circuit just totally dead somewhere and we are right on top of it.  It will come to light soon.  Hang in there.



Offline Paul Birkeland

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Reply #35 on: April 12, 2014, 05:55:49 AM
I think I see a loose wire.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Rhok

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Reply #36 on: April 12, 2014, 06:29:14 AM
You're the freaking man Paul! Excellent attention to detail, it was just making connection with the insulation instead of the wire. As soon as I saw what you saw I removed the solder from that terminal, readjusted the wires, and re soldered, we may be in business now I'm going to do another voltage check.

21: 205.5 V DC

Additionally - LEDs glow!

Will post more momentarily.



Offline Rhok

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Reply #37 on: April 12, 2014, 06:43:14 AM
New results:

1: 080.8 vDC

2: 165 vDC

3: 0 vDC

4: 165 vDC

5: 078.5 vDC

6: 0 vDC

7: 100.8 vDC

8: 0 vDC

9: 100.4 vDC

10: 0 vDC

11: 0 vDC

12: 0 vDC

13: 165 vDC

14: 0 vDC

15: 185 vDC

20: 0 vDC

21: 206.5 vDC

A1: 078.4 vDC

A2: 0 vDC

A4: 0 vDC

A5: 0 vDC

A6: 080.4 vDC

A7: 0 vDC

A9: 0 vDC

B1: 079.9 vDC

B2: 164.8 vDC

B3: 100.6 vDC

B4: 078.5 vDC

B5: 165.1 vDC

B6: 101.4 vDC

B7: 0 vDC

B8: 0 vDC



Offline Rhok

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Reply #38 on: April 12, 2014, 06:58:19 AM
Alright guys, it doesnt look like we're in the clear just yet - I tested the amp with a cheap pair of headphones I did receive audio (awesome! and thank you for getting me that far!) however, I'm not receiving any output from the right channel.

EDIT:

I've also took some additional pictures: http://s752.photobucket.com/user/mikemathis3/library/xx

« Last Edit: April 12, 2014, 07:29:09 AM by Rhok »



Offline Strikkflypilot

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Reply #39 on: April 12, 2014, 10:39:53 AM
Maybe a longshot but tried to swap inputs?

Home system:
Sources: Ibasso DX90, Google Chromecast Audio optical out
DAC: Schiit Gumby
Amp: Bottlehead Mainline
http://bottlehead.com/smf/index.php?topic=7463.0
Phones: HD800S

Office:
Sources: Iphone/ Ipod
DAC: Dragonfly Red+Jtrbug
Amp: Crack/Speedball heavily modded
Phones: HD580,HD600 grilles


Offline Rhok

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Reply #40 on: April 12, 2014, 10:52:45 AM
I did not, but I just tried - same issue.



Offline Strikkflypilot

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Reply #41 on: April 12, 2014, 11:10:19 AM
So You swapped inputs and still hear music on your left headphone speaker?

Home system:
Sources: Ibasso DX90, Google Chromecast Audio optical out
DAC: Schiit Gumby
Amp: Bottlehead Mainline
http://bottlehead.com/smf/index.php?topic=7463.0
Phones: HD800S

Office:
Sources: Iphone/ Ipod
DAC: Dragonfly Red+Jtrbug
Amp: Crack/Speedball heavily modded
Phones: HD580,HD600 grilles


Offline Rhok

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Reply #42 on: April 12, 2014, 11:35:04 AM
I tried to plug the amp to my dedicated soundcard, a usb DAC, and onboard audio, tried swapping RCA jacks around, all resulted in left channel audio only.

If I connect the headphones directly to any of those devices stereo audio works in both channels.



Offline Paul Birkeland

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Reply #43 on: April 13, 2014, 06:26:59 AM
Your voltages all suggest that the amplifier would pass signal.

You can temporarily short together the middle lug of each level of the volume pot, then see if the amplifier will play from both channels.

If it does, you probably have some solder shorting out the right RCA jack.

If it doesn't, you probably have a loose wire feeding the right channel of the headphone jack.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Rhok

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Reply #44 on: April 13, 2014, 08:10:49 AM
I believe this time around I checked the wires that should be relevant for the right channel very closely and do not see anything loose (or not making proper connection). I also don't see any solder that may bridge a connection to cause a short.

Could you please explain how to short the middle lugs of the volume pot for testing?