Trouble shooting an F6 build

[2 picoDumbs]

Check that you haven't shorted the capacitor leads at Q2.
Or just replace the capacitor with a new one if there is any chance the capcitor is bad.

 

[2 picoDumbs]

If you have spares of each just replace both the capacitor and trimpot.

 

[bored184]

At the moment I don't have spares of either one.

 

[Zen Mod]

voltages across zeners need to be practically the same - around 9V1

confirm that

 

[2 picoDumbs]

Already confirmed

 

[Zen Mod]

I see now - post#38

so , most probable explanation is bad trimpot , especially if there was some gray smoke before

 

[2 picoDumbs]

Yep.
I'm starting to think the trimpot may have went poof, because the 1000uF cap leads were/are shorted or the cap is shorted internally.

 

[bored184]

Yep.
I'm starting to think the trimpot may have went poof, because the 1000uF cap leads were/are shorted or the cap is shorted internally.

Would having the jfets switched caused the cap to internally short? I looked at the leads protruding from the underside of the board and I dont know how an external short could of happened.

 

[2 picoDumbs]

No

 

[2 picoDumbs]

Maybe just a poorly manufactured trimpot.

The lesson here is always buy spare parts.

 

[bored184]

Maybe just a poorly manufactured trimpot.

The lesson here is always buy spare parts.

So I have learned.


Since I have got a place an order now should I remove the 9.1 zeners in favor of the LM329?

 

[2 picoDumbs]

A lower voltage zener or lm329 is a good idea.
Anything between 6V and 7V is good.

Use Bourns trimpots. There are so few parts so make sure you buy good quality parts.

 

[bored184]

A lower voltage zener or lm329 is a good idea.
Anything between 6V and 7V is good.

Use Bourns trimpots. There are so few parts so make sure you buy good quality parts.

Parts ordered. I guess I am in a holding pattern till they show up.

 

[2 picoDumbs]

Worth checking the capacitor is ok.
Take it out and test.
Or just replace.

Try not to put too much heat into components when soldering. That is get the soldering iron in and out within 3 seconds.
Allow heat to dissipate before soldering next lead on component.

 

[bored184]

Worth checking the capacitor is ok.
Take it out and test.
Or just replace.

Try not to put too much heat into components when soldering. That is get the soldering iron in and out within 3 seconds.
Allow heat to dissipate before soldering next lead on component.

Is there an optimal temp setting to have a soldering iron set at? I've got a Weller WES51.

 

[2 picoDumbs]

I use 350 degrees Celsius

You don't want to go much cooler though cause you'll end up holding the iron on the pad and lead wire for much longer trying to get the solder to flow.

Time is the enemy.

 

[bored184]

All the parts will be here by tomorrow and I have set time aside Saturday to work on it.

 

[bored184]

I want to confirm something I read. When using the LM329 is R7 and R8 3.3k ohms or 3.6k ohms.

 

[Zen Mod]

not much difference

 

[bored184]

not much difference

Thank you! I have both values. Seeing as the schematic says 3.3k ohms that is what I will go with.