Shure
One is a ground lift switch used to lift from the ground if you have a ground loop problem.
IMO remowing the loop may be a beter solution but ground loops can be real pain so there you go
The other is a bridge diode and 4 caps used to stop DC going in to the trafos
Tiny winy bit of DC on the AC line is enough to upset a thoroide transformer.
At least this is what I have understud from the post but it is much beter explained there.
Update on the F5
Went back in the loft and powered up again No variac used this time
Start up temperature 26C 3.89 A +15 mV
Sun started to setle and oshillating between +5 and -8 mV
I am realy happy with this hope it stays that way.
Still could hear the hum from the traffo definetley mechanical noise but as I powered up the loft PC the noise was burried way below the fan noise from the PC so maybe I am being a bit to fussy.
So plan for tomorow strip down the suply and search for bubus swap the trafo with spare one and DC Blocking.
But maybe just to fussy still is a 1000 VA trafo and it should not make any noise at 4 A
One is a ground lift switch used to lift from the ground if you have a ground loop problem.
IMO remowing the loop may be a beter solution but ground loops can be real pain so there you go
The other is a bridge diode and 4 caps used to stop DC going in to the trafos
Tiny winy bit of DC on the AC line is enough to upset a thoroide transformer.
At least this is what I have understud from the post but it is much beter explained there.
Update on the F5
Went back in the loft and powered up again No variac used this time
Start up temperature 26C 3.89 A +15 mV
Sun started to setle and oshillating between +5 and -8 mV
I am realy happy with this hope it stays that way.
Still could hear the hum from the traffo definetley mechanical noise but as I powered up the loft PC the noise was burried way below the fan noise from the PC so maybe I am being a bit to fussy.
So plan for tomorow strip down the suply and search for bubus swap the trafo with spare one and DC Blocking.
But maybe just to fussy still is a 1000 VA trafo and it should not make any noise at 4 A
Finally got mine up and running. It sounds pretty good so far but I have not sat down and really listened yet. I will rebias in a week. I do have a very slight buzz that is equal in both channels. I may see if lifting the power gnd from earth will help. I will also attempt to clean up the rats nest. Other then that I am pretty happy!
Update
Striped down suply
fitted ground trap (tanks Zen for posting DWG originaly) no 6.3 V caps buth had a couple of 15000 U 63 V to try no change
Changed transformer no change
Tried swaping wires of secondary around slight increase with the 2 fighting each other
Probably just me being fussy or do not buy cheap stuff
or both.
Going to try for same noise now
Striped down suply
fitted ground trap (tanks Zen for posting DWG originaly) no 6.3 V caps buth had a couple of 15000 U 63 V to try no change
Changed transformer no change
Tried swaping wires of secondary around slight increase with the 2 fighting each other
Probably just me being fussy or do not buy cheap stuff
or both.
Going to try for same noise now
Whoo Hoo!!! Hooray! And a very sincere congratulations!
Do you have any photos? We would love to see it!
Sorry no noise
It is absolutley silent but then the tape start and bliss.
Got a very poor set up in the loft just an old tape dek and a pot to set the volume.
Only one chanel running and 4 volts peack out but well bliss.
Is probably one of the fastets amps I have eard
Ist got to get the other channel set up buth with one done the next will be easy peasy.
Ofset steady at + - 2 mV heath spreader temperature 46 C
Cant realy say much about listening impression will have to finish it and get it down from the loft but I am already shure is much beter that the one I have at the moment.
I just need a proper preamplifier (hint)
It is absolutley silent but then the tape start and bliss.
Got a very poor set up in the loft just an old tape dek and a pot to set the volume.
Only one chanel running and 4 volts peack out but well bliss.
Is probably one of the fastets amps I have eard
Ist got to get the other channel set up buth with one done the next will be easy peasy.
Ofset steady at + - 2 mV heath spreader temperature 46 C
Cant realy say much about listening impression will have to finish it and get it down from the loft but I am already shure is much beter that the one I have at the moment.
I just need a proper preamplifier (hint)
Well First of all what board are you using? I'm using a Peter Daniel's board.
Basically I took the RCA ground, (right from the RCA jack) and connected them together, and from there, I connected those to the Power ground. I did not run an extra ground from the amp board at all. I let the RCA ground that connects to the amp board run towards the RCA jack. That removed all hum whatsoever.
I hope that makes sense.
Basically I took the RCA ground, (right from the RCA jack) and connected them together, and from there, I connected those to the Power ground. I did not run an extra ground from the amp board at all. I let the RCA ground that connects to the amp board run towards the RCA jack. That removed all hum whatsoever.
I hope that makes sense.
Ahh I see, attach the shield only at the RCA side. and remove the white ground from the board. Connect the RCA grounds together right at the pins and put a wire from the middle back to the star ground there. That should solve the hum.
I had the same problem until I did that.
I circled what I did (its the white wire) I should have put the ground in the middle, but oh well.. (please ignore the mess of the extra caps.... )
I had the same problem until I did that.
I circled what I did (its the white wire) I should have put the ground in the middle, but oh well.. (please ignore the mess of the extra caps.... )
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