F6 Illustrated Build Guide

[2 picoDumbs]

Possibly the RCA connector on F6 is not isolated from the chassis.

Disconnect everything again.

On F6 Measure from RCA ground pin to chassis

 

[2 picoDumbs]

Also check the RCAs on the Korg if they are isolated from the chassis

Measure across RCA ground pin and chassis

 

[2 picoDumbs]

Also measure resistance across signal pin and shield pin of RCA cables
You could have a bad RCA cable

check both cables

 

[Yaho]

Possibly the RCA connector on F6

With RCA disconnected from the B1, 10.6 ohm from RCA pin to the chassis

On the pre side, 2.6 ohm.

I will try to reinstall the RCAs.

 

[WKCox]

@Yaho - your link to the SMPS was to an open chassis supply (RS-25). Is in mounted in your B1 and is its chassis grounded or floating?

 

[Yaho]

your link to the SMPS was to an open chassis supply

I am assumming that it is completely open. I even put an isolation trans infront of it.

is its chassis grounded or floating

chassis is floating...not connected to the pre chassis at all

 

[jameshillj]

75,000uF per rail? That's 150,000uF for the amp, yes? 0.15F? Did I get this right?

 

[2 picoDumbs]

Keep working on finding out why F6 PSU 0V to Korg Chassis measures 0 Ohms

It should not be less than your original 8.8 Ohms measurement


This is your problem


Hopefully the only one.

 

[Yaho]

75,000uF per rail? That's 150,000uF for the amp, yes? 0.15F? Did I get this right?

yes,you got this right.

 

[2 picoDumbs]

I need to think more

 

[Yaho]

I need to think more

Me too...

The B1 board is connected to the pre chassis! Do you think?

Nope. that's not it. I just checked

 

[2 picoDumbs]

I am trying to visualise this in my head and the brain is starting to second guess.
Just forget what I said about finding that problem (it might not be one)

Draw this on paper showing the 2 pieces of equipment connected via rca include all the measurements

 

[2 picoDumbs]

Did you measure across your RCA cables

 

[2 picoDumbs]

Do 3 more measurements

1) Measure resistance from Meanwell 0V to chassis of Korg Pre
2) Measure resistance from Meanwell Chassis to Korg Pre Chassis
Edit 3) Measure resistance from Meanwell 0V to Meanwell Chassis

Include these measurements in the drawing

If you do this someone will see where the problem is. My brain is fading (lack of sleep).

It will be easier for everyone if you draw what we have so far.

 

[Yaho]

Did you measure across your RCA cables

yes. no reading

1) Measure resistance from Meanwell 0V to chassis of Korg Pre

1.6 ohm

2) Measure resistance from Meanwell Chassis to Korg Pre Chassis

no reading. Meanwell sitting on a wooden platform...glued it

[/QUOTE]Edit 3) Measure resistance from Meanwell 0V to Meanwell Chassis[/QUOTE]
no reading.

I've been working on this all day. My brain is shutting down too.

 

[2 picoDumbs]

Do you use a 3 pin plug or 2 pin mains plug with the Meanwell psu?


THIS COULD BE IT

 

[Yaho]

Do you use a 3 pin plug or 2 pin mains plug with the Meanwell psu?

I am using a 1:1 isolation transformer to supply AC for the meanwell. I thought it would isolatate any possible ground issue and safe as well.

 

[2 picoDumbs]

Do you have a mains cable with 3 wires or 2 wires coming into your Korg?

If you can disconnect your isolation transformer, do that and see if it hums.

 

[Yaho]

Do you have a mains cable with 3 wires

3.
2 to the isolation
1 to the chassis (I am thinking that this may be the cause)...cut off the safety wire to the chassis?

I will connect the MW directly to the main power.

 

[2 picoDumbs]

Yes

Get rid of the chassis earth connection.
It should only be connected to neutral

The earth wire can attach to the isolated meanwell chassis but not the korg chassis