Hi,
The parts arrived and I installed them, no difference. I actually think it picked up more hum and the scope shows new spikes where there were none. I was carefull with the solder and there was no smoke when I turned it on. I only installed the snubbers in one amp to hear a difference. the other amp has quit working; see below.
One has quit working.
I turned it on a heard a click,pop and that was that. I put it on the scope and there is no signal coming out of the OPT, duh! There is a signal coming out of the 300b (hum) going into the high voltage side of the OPT. Continuity is the same as the working amp, I checked.
Any ideas where to start looking?
I should move to the U.K. or Belgium is what I should do.
thanks for your help, again, and again and again, ect.
The parts arrived and I installed them, no difference. I actually think it picked up more hum and the scope shows new spikes where there were none. I was carefull with the solder and there was no smoke when I turned it on. I only installed the snubbers in one amp to hear a difference. the other amp has quit working; see below.
One has quit working.
I turned it on a heard a click,pop and that was that. I put it on the scope and there is no signal coming out of the OPT, duh! There is a signal coming out of the 300b (hum) going into the high voltage side of the OPT. Continuity is the same as the working amp, I checked.Any ideas where to start looking?
I should move to the U.K. or Belgium is what I should do.
thanks for your help, again, and again and again, ect.
Thanks Frank
It's working now. What is strange is I swapped all the tubes one amp for the other and now both are working? I'll keep a ear on it.
Now, what about those rectifers? I am willing to do something completely different. Any suggestions? I have to live with the 7.2v 1.5a output from the PWT, but there has to be another way to smooth this thing out.
Also, how could I check for ground loop? I notice when I touch the attenuator knob the spikes drop right off on the scope. I don't want to stand holding the knobs while I listen to music.
It's working now. What is strange is I swapped all the tubes one amp for the other and now both are working? I'll keep a ear on it.
Now, what about those rectifers? I am willing to do something completely different. Any suggestions? I have to live with the 7.2v 1.5a output from the PWT, but there has to be another way to smooth this thing out.
Also, how could I check for ground loop? I notice when I touch the attenuator knob the spikes drop right off on the scope. I don't want to stand holding the knobs while I listen to music.
Paul,
You said:
There should be an earth, for safety reasons alone, on such equipment.
Also, does it do the same thing if you touch the chassis?
And now for the obvious:
Is the volume control mounted on an insulator? Eg wood. If so, have you taken steps to connect a grounding wire from the volume control's body to the star earth point?
If not....do it.
Cheers,
You said:
Is the chassis earthed? Do you have an earth connection in your house?
There should be an earth, for safety reasons alone, on such equipment.
Also, does it do the same thing if you touch the chassis?
And now for the obvious:
Is the volume control mounted on an insulator? Eg wood. If so, have you taken steps to connect a grounding wire from the volume control's body to the star earth point?
If not....do it.
Cheers,
Hi John,
Yes, the chassis has a lead to the earth connection of the IEC a/c receptacle.
I believe all the earth connections on the sockets are connected to a 8' ( 2.5 meter?) copper plated rod that is buried in the ground next to where the mains power comes into the house fuse panel.
Oddly, I did not try this yet. I will let you know.
The attenuator is mounted to copper plate that is not earthed to star ground. The attenuator does have a neagtive connection that I did wire to star ground.
Thanks for the reply and any other ideas I might look at?
Yes, the chassis has a lead to the earth connection of the IEC a/c receptacle.
I believe all the earth connections on the sockets are connected to a 8' ( 2.5 meter?) copper plated rod that is buried in the ground next to where the mains power comes into the house fuse panel.
Oddly, I did not try this yet. I will let you know.
The attenuator is mounted to copper plate that is not earthed to star ground. The attenuator does have a neagtive connection that I did wire to star ground.
Thanks for the reply and any other ideas I might look at?
AH...
Hi,
Well done John.
Now if that pot is sitting where I think it is, namely the top copper plate, then that would explain a lot.
I assume the grounding has been done on the bottom plate which I assume is a copper plate as well.
If star grounding is to be applied,both should be connected at the same point.
Then we can at long last tackle the 7.2 heater voltage.
Good luck Paul,
Hi,
Well done John.
Now if that pot is sitting where I think it is, namely the top copper plate, then that would explain a lot.
I assume the grounding has been done on the bottom plate which I assume is a copper plate as well.
If star grounding is to be applied,both should be connected at the same point.
Then we can at long last tackle the 7.2 heater voltage.
Good luck Paul,
Hello,
Well I tried everything I could think of or see. I solder wires to ground all chassis plates to star ground. I removed all the ground wires from the shielded wires, ( thought this might be introducing a/c back through ground). Tried the snubbers, no difference. Soldered a wire to connect the two star ground points together, ( but the copper plate makes that a mute point).
I believe my alternative is to make all filaments d/c, but really do not know. I could try this, I believe this is a matter of buying some filament trannys. Would this leave my PWT unloaded to the point that voltage on the B+ would rise because of less current draw?
Any other Ideas and new suggestions?
Should I sell them to Frank or John for $1.50?
Well I tried everything I could think of or see. I solder wires to ground all chassis plates to star ground. I removed all the ground wires from the shielded wires, ( thought this might be introducing a/c back through ground). Tried the snubbers, no difference. Soldered a wire to connect the two star ground points together, ( but the copper plate makes that a mute point).
I believe my alternative is to make all filaments d/c, but really do not know. I could try this, I believe this is a matter of buying some filament trannys. Would this leave my PWT unloaded to the point that voltage on the B+ would rise because of less current draw?
Any other Ideas and new suggestions?
Should I sell them to Frank or John for $1.50?
Life Happens
Hi,
Sorry I have been gone awhile. Life has a habit of taking up my time and attention.
Now I do not know if I have been missed, but I am sure glad you guys, ( and gals?) are out there.
I have been thinking about the grounding in the JE 300b's and I did use two star grounds. Both are directly coupled to the copper chassi and are not isolated from each other or from the a/c mains safety ground. What if I isolated the two star grounds above the chassi and from each other? Leaving only the a/c mains earth connected to the chassi for safety?
Hi,
Sorry I have been gone awhile. Life has a habit of taking up my time and attention.
Now I do not know if I have been missed, but I am sure glad you guys, ( and gals?) are out there.
I have been thinking about the grounding in the JE 300b's and I did use two star grounds. Both are directly coupled to the copper chassi and are not isolated from each other or from the a/c mains safety ground. What if I isolated the two star grounds above the chassi and from each other? Leaving only the a/c mains earth connected to the chassi for safety?
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