Final voltage check incorrect- Crack [resolved]

[andrewduckworth@mac.com]

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.

 

[Paul Birkeland]

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). 

 

[andrewduckworth@mac.com]

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

 

[Paul Birkeland]

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.

 

[andrewduckworth@mac.com]

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?

 

[Paul Birkeland]

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. 

 

[andrewduckworth@mac.com]

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

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

 

[Paul Birkeland]

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

 

[andrewduckworth@mac.com]

Ok thanks Paul. Will do.

 

[andrewduckworth@mac.com]

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