I have a Decware zkit that has worked fine until recently; I changed the input tube to a 5670 using an adapter and the amp suddenly started humming and one channel died. After going through and testing components it seems everything is fine but it just makes a loud digital popping sound from both sides (sounds like the old Atari “tank plus” game).
I can’t rationalize what it could be other than the tube socket was damaged by the adapted pins, but when I removed the socket it appears to be fine, with connection from each pin socket to lug, and no cross current.
The power transformer seems fine, and the power supply section is producing appropriate DC voltage. I’ve tried different tubes with the same effect.
Now I am looking at the output transformers- I get continuity across the positive and negative speaker jacks on both sides. Are my output transformers blown?
I can’t rationalize what it could be other than the tube socket was damaged by the adapted pins, but when I removed the socket it appears to be fine, with connection from each pin socket to lug, and no cross current.
The power transformer seems fine, and the power supply section is producing appropriate DC voltage. I’ve tried different tubes with the same effect.
Now I am looking at the output transformers- I get continuity across the positive and negative speaker jacks on both sides. Are my output transformers blown?
The original was a 6n1p. I have used the 5670 with that adapter before but not in that amp or style tube socket.
All parts are easy enough to check and compare between channels.
We should know more about the adaptor manufacture.
We should know more about the adaptor manufacture.
Measure the adapter,pin for pin.
Could also be a free floating shield, cannot see 6N1 shield connection (pin9) in that diagram
5670 should be ok in that circuit.
Is there the same fault if you put the 6N1 back in?
Could also be a free floating shield, cannot see 6N1 shield connection (pin9) in that diagram
5670 should be ok in that circuit.
Is there the same fault if you put the 6N1 back in?
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Yes, as I said in my original post, I have checked all the parts and all check fine. I was left asking the question about the output transformer.
I have only used the 6n1p since the original problem with the 5670 with the adapter. I have not tried the adapter or that tube since.
If the output transformer blew it would be on the primary side. With the output tubes removed, measure each transformer from pin 7 to the B+ tap and see if they match. Should be 100 ohms or something like that.
OPT secundary windings are floating (not a good idea).
You measured continuity beween one of the primaries and its secundary, or where exactly?
You measured continuity beween one of the primaries and its secundary, or where exactly?
One more thing, the output tubes supressor grids are also floating, thats really really bad, it should be connected to the cathode.
What was the designer thincking?
Geez, there should be a law forbidding publishing such designs....
What was the designer thincking?
Geez, there should be a law forbidding publishing such designs....
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are you comfortable measuring a live amp? coz I'd like to know the voltages on the cathodes, to see if all the tubes are conducting. prob a good idea to measure everything.
194.6 in both opt primaries sound ok.
Can you safely, without electrocuting yourself, measure all voltages ?
If you can, before doing so, short both inputs and leave, the speakers connected, pull the output tubes, and measure cathode and anode voltages of the 6n1 in both chanels for comparement, if they are alike, your 6n1 should be ok
Proceed with measuring the voltages across the grid resisors of the output tubes. There should not be any!
Next, switch off, make sure ps caps are discharged and then short those 0.1uF caps connecting the supressor grids of the output tubes to cathode.
Next, pull the 6n1, insert the output tubes, measure cathode, screengrid and anode voltages for comparement.
Measure also if there is any dc voltage between the output transformer secundary windings and ground, there should not be any.
If you find any differences between channels report back.
Always make sure to switch off and that the ps caps are discharged before touching anything with your bare hands.
Can you safely, without electrocuting yourself, measure all voltages ?
If you can, before doing so, short both inputs and leave, the speakers connected, pull the output tubes, and measure cathode and anode voltages of the 6n1 in both chanels for comparement, if they are alike, your 6n1 should be ok
Proceed with measuring the voltages across the grid resisors of the output tubes. There should not be any!
Next, switch off, make sure ps caps are discharged and then short those 0.1uF caps connecting the supressor grids of the output tubes to cathode.
Next, pull the 6n1, insert the output tubes, measure cathode, screengrid and anode voltages for comparement.
Measure also if there is any dc voltage between the output transformer secundary windings and ground, there should not be any.
If you find any differences between channels report back.
Always make sure to switch off and that the ps caps are discharged before touching anything with your bare hands.
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