Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: canuckaudio on October 23, 2014, 05:29:56 AM

Title: Crack TRS tip voltage too high
Post by: canuckaudio on October 23, 2014, 05:29:56 AM

Hi.

I just completed the voltage tests on my Crack unit.  Everything seems to check out except for the TRS tip.  LEDs are lighting up.
The TRS tip voltage is 85V.  The TRS ring voltage is 0V.

Any suggestions on what I should check/resolder?

Thanks,

Edmond

Title: Re: Crack TRS tip voltage too high
Post by: fullheadofnothing on October 23, 2014, 09:17:29 AM

Does it stay at 85V?

Have you done this: http://bottlehead.com/smf/index.php?topic=2946.0 (http://bottlehead.com/smf/index.php?topic=2946.0) yet?

Title: Re: Crack TRS tip voltage too high
Post by: canuckaudio on October 23, 2014, 09:24:28 AM

It stays at 85V.
I'll try connecting the unused terminals to ground.
Thanks for the quick response!

Edmond

Title: Re: Crack TRS tip voltage too high
Post by: Paul Birkeland on October 23, 2014, 10:58:36 AM

I wouldn't do that mod just yet, depending on what's wrong, you may end up roasting your power supply.

I think the white wire going to your headphone jack isn't connected to the correct terminal, please double check that.  Otherwise, be sure that there isn't any debris shorting T6/T7 or T9/T10.

Also, a floating 2.49K resistor on the TRS jack could cause this voltage to not bleed off, so double check those.
-PB

Title: Re: Crack TRS tip voltage too high
Post by: canuckaudio on October 23, 2014, 04:45:30 PM

Hi Paul.
I can confirm that the white wire is going into 10L as per the instructions on page 33.
I can't see anything shorting T6/T7 or T9/T10.
Can you help me understand what a floating resistor is?  Neither of the 2.49K resistors on the TRS are moving.
Thanks for the ideas on where to look.
Edmond

Title: Re: Crack TRS tip voltage too high
Post by: Chris65 on October 23, 2014, 04:50:20 PM

'Floating' means not (properly) connected. Check you have a good connection on the terminals by measuring with your DVM, sometimes they can look ok but are not in good electrical contact.

Title: Re: Crack TRS tip voltage too high
Post by: Paul Birkeland on October 23, 2014, 05:10:47 PM

I'd also double check that the 160uF 100V caps are oriented correctly, with the striped side of each facing the outside of the chassis.

It's somewhat common to see loose ground connections on the TRS jack.  It may be that the two 2.49K resistors are well connected, but the black wire that connects the two sleeve terminals on the jack may be loose on one end.

-PB

Title: Re: Crack TRS tip voltage too high
Post by: canuckaudio on October 23, 2014, 05:31:25 PM

Paul.  Do you mean the 100uF 160V caps?  If so, all stripes facing outside.  The black wire is soldered solid to the jack - no loose ends.
Thanks.

Title: Re: Crack TRS tip voltage too high
Post by: Paul Birkeland on October 23, 2014, 06:09:53 PM

Is the high voltage present on 6 or 10? Can you post a quick photo of the TRS jack and the octal socket?

-PB

Title: Re: Crack TRS tip voltage too high
Post by: canuckaudio on October 23, 2014, 06:47:26 PM

The high voltage is also present on 10.  6 has 0 Volts.
Images attached.

Thank you

Title: Re: Crack TRS tip voltage too high
Post by: Paul Birkeland on October 24, 2014, 08:01:25 AM

I can see that one 2.49K resistor is blown, that will have to be replaced, but not just yet.

B6 looks to be connecting to T10, which is your issue. The 2.49K resistor can be a 2K-3K resistor, wattage is unimportant.

-PB

Title: Re: Crack TRS tip voltage too high
Post by: canuckaudio on October 24, 2014, 09:40:54 AM

Thank you so much for being my second set of eyes!!
I've corrected the B6 connection and connected it to T9.  I've attached an image of the fix.

I tested the resistors and both are working, so I plugged in my HD-650 and....WOW!  loving the sound.  will be doing lots of listening during the coming weeks on a kit that I assembled myself.  Feels great  ;D

Big thumbs up and thank you to Paul.

Edmond

Title: Re: Crack TRS tip voltage too high
Post by: Paul Birkeland on October 24, 2014, 11:02:19 AM

Yes, a general electronics store should have what you need.