Bottlehead Forum

Bottlehead Kits => S.E.X. Kit => Topic started by: eudisld15 on January 04, 2019, 10:21:17 AM

Title: S.E.X 3.0 C4S humming after replacing heater bell cap [resolved]
Post by: eudisld15 on January 04, 2019, 10:21:17 AM
 folks.

Heater cap was looking a bit ugly so i took it off and polished it up. After putting it back on my SEX developed humming (louder on the left channel but present in both).

Followed the manual and did resistance checks. Passed all checks. Then I did a voltage test and found a damaged sparky wire. Replaced it and got a pass on the voltage test. Lastly did a c4s voltsges test and it passes just fine.

Replaced the pot with an identical a100k from my crack kit thats waiting to be built. I am using a different power cord and my outlets are grounded.

When i checked the rca jack i noticed that the humming is magnified when rca cables are plugged in while connected to a source. Tried replacing the rca cables. Still hums. Used my phone as a source. Still hums.

Did some futher testing and desoldered the rca jacks and tested the leads. Shorting the rca leads together doesnt produce hum. Putting the positive peg or negative part of the rca cable on the solid blue cat6 cable produces a hum but not one the white blue lead. Same for the solid orange (but again to a much lesser effect) vs the white orange lead.

Any ideas as to what I screwed up?

Tonight I'll do the resistance and voltage check and post values. I am at work. However I have no issues passing the tests even after multiple checks.

Also double checked that the power transformer threads and spacers are setup right and tight.
Title: Re: S.E.X 3.0 C4S humming after replacing heater bell cap
Post by: Doc B. on January 04, 2019, 11:27:54 AM
Heater cap. Do you mean the power transformer bell end? If so, did you miss a lock washer when you reinstalled the bell end? Are the screws and nuts all snug?
Title: Re: S.E.X 3.0 C4S humming after replacing heater bell cap
Post by: eudisld15 on January 04, 2019, 11:42:38 AM
Quote from: Doc B. on January 04, 2019, 11:27:54 AM
Heater cap. Do you mean the power transformer bell end? If so, did you miss a lock washer when you reinstalled the bell end? Are the screws and nuts all snug?

My apologies. It is indeed Power Transformer Bell End.

I made sure to apply all the parts as prescribe including the nuts and washers and tightened it up. I did forget to mention an important bit and that is I painted it with plasti dip. If I am getting proper resistance checks could improperly painted bell cause issue still?
Title: Re: S.E.X 3.0 C4S humming after replacing heater bell cap
Post by: Paul Birkeland on January 04, 2019, 02:03:16 PM
Did the amp hum before installation of the C4S kit? 

Can you post some photos of your build?
Title: Re: S.E.X 3.0 C4S humming after replacing heater bell cap
Post by: eudisld15 on January 04, 2019, 02:18:43 PM
Quote from: Paul Birkeland on January 04, 2019, 02:03:16 PM
Did the amp hum before installation of the C4S kit? 

Can you post some photos of your build?

No hum.

Here is what I have on my phone. I won't be able to post any other pictures until done with work in 3 hours  :(
Title: Re: S.E.X 3.0 C4S humming after replacing heater bell cap
Post by: Paul Birkeland on January 04, 2019, 06:31:15 PM
You have a backwards PN2907. 
Title: Re: S.E.X 3.0 C4S humming after replacing heater bell cap
Post by: eudisld15 on January 04, 2019, 08:28:09 PM
Quote from: Paul Birkeland on January 04, 2019, 06:31:15 PM
You have a backwards PN2907.


Haha that did it!!

This sounds amazing again!