Bigbottle Phonostage Builders thread.

[sebmeb]

the voltage is way too high. I do not think it is the transformer I think it is something with the board. It turns on with a little click - og turns off with a little click

 

[patrickblue]

This seems a common theme with these transformers, Oli has said several times in this thread that they are out of spec, I was getting 210v out of mine.
It shouldn't really be much more than 180v to drop down to 160-170 in use.

 

[patrickblue]

the voltage is way too high. I do not think it is the transformer I think it is something with the board. It turns on with a little click - og turns off with a little click

The click sounds like the relays which switch between mc and mm.
Is your cart mm or mc?

 

[sebmeb]

my cart is mm

 

[patrickblue]

It clicks when you turn it on because when the board is unpowered the relays are set for mc, If it's switched for mm, the relays will click when you turn it on to move to mm. And it will do the same when you turn it off. When it clicks on, the two LEDs should also light up.

That shouldn't stop it working, and even if it somehow switches to mc while being in use, you will still get very distorted sound from it, not silence,
Just to check, switch it to mc then turn it on and off, it shouldn't click

 

[sebmeb]

Absolute worth a try will do it tomorrow

 

[patrickblue]

Also, have you tried changing the valves/tubes? That's probably your first point of call

 

[sebmeb]

yes no difference

 

[Ryssen]

Does the transformer get hot?

 

[patrickblue]

Well, the best thing to do is take it out of the case, or take the lid off so you can test for voltage from the transformer when it cuts out. That will establish if it's transformer or board.
Then work from there.

 

[Ryssen]

Or if any of the regulators get extra hot and shuts down.

 

[sebmeb]

Tried today with MC load.
Hv before the load is 189v
Lv before the load is 11.2v in one channel and 10.5 in the other.
The transformer is not getting warm ( 2hours)
It is still shutting down after 10 min.

What to do next?

 

[patrickblue]

So is the transformer still supplying power when it shuts down?

 

[sebmeb]

Yes transformer is still alive

 

[patrickblue]

Sorry for taking ages, I'm at work.
I suspect that its what Ryssen said, that one of the regulators is overheating.
Ensure they are thermally, but not electrically connected to the heatsinks.

 

[Vivant]

Tried today with MC load.
Hv before the load is 189v
Lv before the load is 11.2v in one channel and 10.5 in the other.
The transformer is not getting warm ( 2hours)
It is still shutting down after 10 min.

What to do next?

Do the valve heaters go out, if so the 7805 is overheating probably.
It needs to be tightly bolted to the heatsink.

If the heaters remain alive then the fault is on the HT somewhere.
Check that the smaller electrolytic capacitors are inserted the right way around to start with.

 

[sebmeb]

Thanks to all for helping. It was the 7805 regulator that was overheating. I think the problem is solved thanks to you guys. The system has now been running for 4 hours with excellent music. It took me a year to finish the build.

The best - That is a keeper.

Thanks to all

 

[Marra]

Enjoy it's a stunning phono stage.

 

[sebmeb]

I have seen several bildings where R7 is replaced with a wire. What is the meaning of R7 ????

and does it matter which color of led you are using ???

Regards

 

[Bigman80]

I have seen several bildings where R7 is replaced with a wire. What is the meaning of R7 ????



and does it matter which color of led you are using ???



Regards

Yes it matters.

I'd you use the MultiFET PCBs, then the resistor in R7 should be removed.

If not, then R7 should be kept in place