Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: Mr Zeus on June 18, 2014, 10:27:55 AM

Title: Resistance Fail Terminal 6 [solved]
Post by: Mr Zeus on June 18, 2014, 10:27:55 AM

Hi Guys,

I was wondering if anyone could offer advice.
My Crack is failing the resistance check on terminal 6 it is reading zero ohms.
I have checked and rechecked but I can't see a short or bad joint.
All other terminals read correct. Any ideas what I need to look for?

Thank you.
Bob Z

Title: Re: Resistance Fail Terminal 6
Post by: Paul Birkeland on June 18, 2014, 10:31:24 AM

Hello Bob,

Welcome to the forum! 

There is a modification sticky on the Crack board regarding the output jack.  If you have implemented this modification, then 6 and 10 will read 0.

Otherwise, there are a few things to check.  First off, all that connects to terminal 6 is a single wire and the banded end of a capacitor.  Check where the red wire connects on the other end.  It should connect to the "ring" terminal of the headphone jack, which is the middle lug on the inboard side.  If you have it connected to the "sleeve" terminal (the bottom row), then one would expect a reading of 0 Ohms here.

-PB

Title: Re: Resistance Fail Terminal 6
Post by: Mr Zeus on June 18, 2014, 11:49:02 AM

Hello PB,
I haven't done any mod except for a note in the manual that said:
Attach and solder
one end to power transformer
terminal 4. Attach and solder the
other end to terminal 22L.
REVISION 5/6/10:
Making this wire 3” long and
connecting it to Terminal 14U
instead of terminal 22L may
yield more quiet operation.

Is this what you meant?

Cheers,
Bob

Title: Re: Resistance Fail Terminal 6
Post by: Mr Zeus on June 18, 2014, 12:08:19 PM

Hi PB
Sorry I did check that the only connections to terminal 6 are the banded side of the capacitor and the middle connection on the headphone jack on the inboard side as well.
That is what has me confused.

Regards
Bob

Title: Re: Resistance Fail Terminal 6
Post by: Paul Birkeland on June 18, 2014, 01:15:07 PM

Disconnect that red wire and see if your resistance reading changes.

-PB

Title: Re: Resistance Fail Terminal 6
Post by: Mr Zeus on June 19, 2014, 08:00:13 AM

Hi PB,

Disconnecting the red wire made no difference.
However I have a new meter and have realised I have accidentally set it wrong. It's not reading zero its 0,L on the M ohms range.
I think the resistor on the headphone jack might be duff or more likely I fried it when soldering.
If I measure from ground to the white wire on the jack its 2.4 K ohms but ground to red wire is over limit even on M ohms.

Does this sound feasible, or is it likely to be something else?

Regards
Bob

Title: Re: Resistance Fail Terminal 6
Post by: Paul Birkeland on June 19, 2014, 08:02:13 AM

Yes, it sounds like that resistor is not well connected.

A replacement would likely be easy to source locally, anything between 2K and 5K will do the job properly.  Alternatively, you could measure the resistance between the wires poking out of each side of that resistor to see if it still reads 2.49K.  If it does, just crimp the leads nice and tightly against the headphone jack, then reheat those joints.  (Do not add solder)

Title: Re: Resistance Fail Terminal 6 (Solved)
Post by: Mr Zeus on June 20, 2014, 08:12:34 AM

Thanks for your help PB it was the resistor soldering. It looked ok even with a magnifying glass but resoldering it fixed the issue.
I just have to fix the wire I cut now.

Best Regards
Bob