Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: [email protected] on March 02, 2021, 03:04:46 AM

Title: Final voltage check incorrect- Crack [resolved]
Post by: [email protected] on March 02, 2021, 03:04:46 AM

Dear All, sadly my voltage check has revealed a problem and I am looking for some help resolving it please.

1. 226v
2. 173
3. 0
4. 229
5. 78
6. 0
7.102
8. 0
9. 104
10. 0

This is my first kit and would greatly value advice from the community. Thanks
Andrew Duckworth, East Hoathly UK.

Title: Re: Final voltage check incorrect- Crack
Post by: Paul Birkeland on March 02, 2021, 05:04:53 AM

Are both black wires on the headphone jack well soldered?

Do both LEDs on the 9 pin socket illuminate?  (no need to reheat the solder joints on those connections if one is not)

Terminal 2 and terminal 4 are wired together with a piece of wire, so the 50V of difference between the two suggests that you have a very loose wire in your amp (not necessarily the wire between 2 and 4 though). 

Title: Re: Final voltage check incorrect- Crack
Post by: [email protected] on March 02, 2021, 06:35:00 AM

many thanks Paul.
I resoldered the black wires on the headphone jack.
Both LED's illuminate.
I have inspected all joints with magnification and tugged them with tweezers.

resistance check is good
Voltage readings are now

1. 164
2. 377
3. 0
4. 376
5. 167
6. 0
7. 230
8. 0
9. 230
10. 0

i rechecked the transformer output readings which were all fine.

?? Andrew

Title: Re: Final voltage check incorrect- Crack
Post by: Paul Birkeland on March 02, 2021, 06:58:23 AM

You have a loose wire in the amp still.

I would reheat every solder joint in the amp other than A3, A8, the 9 pin socket center post, and the power switch.

You can also post build photos if you'd like, but the specific issue you're having is related to a cold solder joint.

Title: Re: Final voltage check incorrect- Crack
Post by: [email protected] on March 12, 2021, 10:59:42 PM

Thanks Paul, I will post some pics. I noticed the the voltages are now symmetrical across 1-5 and 6-10. Is that any help in pointing towards the cold joint?

Title: Re: Final voltage check incorrect- Crack
Post by: Paul Birkeland on March 13, 2021, 05:18:23 AM

Could you post what they are?

It should take less than 30 minutes to go through a stock Crack and reheat all the solder joints. 

Title: Re: Final voltage check incorrect- Crack
Post by: [email protected] on March 13, 2021, 09:41:03 PM

1. 166v
2. 376v
3. 0v
4. 376v
5. 166v

6. 0v
7. 230v
8. 0v
9. 230v
10. 0v

Title: Re: Final voltage check incorrect- Crack
Post by: Paul Birkeland on March 14, 2021, 07:09:10 AM

You need to reflow all of the solder joints in your amplifier.

Title: Re: Final voltage check incorrect- Crack
Post by: [email protected] on March 14, 2021, 10:30:20 AM

Ok thanks Paul. Will do.

Title: Re: Final voltage check incorrect- Crack
Post by: [email protected] on March 19, 2021, 12:43:56 AM

Dear Paul, Crack reheat completed. All voltages correct now. Whilst I am not seeking an award for incompetence or stupidity, It is possible that i set the multimeter to AC when checking the voltages last time. Doh.

I might also have clipped the black multimeter lead to terminal 12 on the transformer instead of 12U!

Thank you for your kind advice and patience.

The Crack sounds magically wonderful!

Speedball next but not quite yet!

Andrew