Thanks Win.
Now I see Hifi Collective has them listed as power tubes. Between American English, British English and German, there are 2.5 times as many names and terms to remember.
I have some Gold Lions on the way as well as more mini grabbers. (My alligator clip test leads make me nervous).
Now I see Hifi Collective has them listed as power tubes. Between American English, British English and German, there are 2.5 times as many names and terms to remember.
I have some Gold Lions on the way as well as more mini grabbers. (My alligator clip test leads make me nervous).
Seems now I'm getting a positive voltage on the grid of the left channel output tube.
Have I got the right pin for the output tube grid voltages??
I don't know how this would have changed from my previous checkout but it would actually be helpful as it would point to something going wrong.
If it means anything; the one thing that's different with this checkout from the other times is that I left the test speakers hooked up from the previous testing.
For what it's worth, here's a shot of my notes during checkout
Going through the schematic step by step and checking resistors again, so far R33 & 34, R18 & 29, R14 & 25, R16 & R27, R27 & R28 all check out perfectly
I can't get reliable readings from the coupling caps while in the board but C9 & C11 both give similar readings which seem to say they're doing something. (The board is soldered in and those caps are on top).
Anyway, if I'm reading the grid slot for the output tubes correctly, I hope that's the smoking gun that says what's going on.
Lastly, fwiw, here's a photo of the board in place.
Have I got the right pin for the output tube grid voltages??
I don't know how this would have changed from my previous checkout but it would actually be helpful as it would point to something going wrong.
If it means anything; the one thing that's different with this checkout from the other times is that I left the test speakers hooked up from the previous testing.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
For what it's worth, here's a shot of my notes during checkout
An externally hosted image should be here but it was not working when we last tested it.
Going through the schematic step by step and checking resistors again, so far R33 & 34, R18 & 29, R14 & 25, R16 & R27, R27 & R28 all check out perfectly
I can't get reliable readings from the coupling caps while in the board but C9 & C11 both give similar readings which seem to say they're doing something. (The board is soldered in and those caps are on top).
Anyway, if I'm reading the grid slot for the output tubes correctly, I hope that's the smoking gun that says what's going on.
Lastly, fwiw, here's a photo of the board in place.
An externally hosted image should be here but it was not working when we last tested it.
Just out of curiosity, can someone tell me what this open spot is in the middle of C11?
It's only on this side (left channel) but not on the right (C9). Same on both my newer board as on Gavin's original but I don't see it on the schematic.
It's only on this side (left channel) but not on the right (C9). Same on both my newer board as on Gavin's original but I don't see it on the schematic.
An externally hosted image should be here but it was not working when we last tested it.
I don't know much about Germany ( took the language, but my hick southern accent is apparently incompatible - my instructor finally told me I didn't belong in higher education. In fairness to her, I also had an english teacher tell me the same thing 
)
Win W5JAG[/QUOTE]
My French teacher in 9'th grade offered to pass me with a D for the year if I promised not to come back. I lasted 1 semester in Spanish....oh well.
) Win W5JAG[/QUOTE]
My French teacher in 9'th grade offered to pass me with a D for the year if I promised not to come back. I lasted 1 semester in Spanish....oh well.
I don't know much about Germany ( took the language, but my hick southern accent is apparently incompatible - my instructor finally told me I didn't belong in higher education. In fairness to her, I also had an english teacher tell me the same thing
Win W5JAG
My French teacher in 9'th grade offered to pass me with a D for the year if I promised not to come back. I lasted 1 semester in Spanish....oh well.[/QUOTE]
Wowsa!
I guess it's easier for some although I learned more Spanish working in a restaurant than I ever did in high school Spanish. Immersion is the only way for me. I'm conversational in French after 2 years there. Can get by in Turkish. My German though is slow (Berlin's 2nd language is definitely english) and based primarily around audio now.
Have you tried that channel that shows proper voltages to see if it works properly?
B+ voltage on the grid of the 300B sure seems like a bad mosfet. I can't think of another path for the B+ to get there. You are having terrible luck with these, or have gotten a bunch of bad parts .
Win W5JAG
B+ voltage on the grid of the 300B sure seems like a bad mosfet. I can't think of another path for the B+ to get there. You are having terrible luck with these, or have gotten a bunch of bad parts .
Win W5JAG
Thanks very much Win. I agree but I keep wondering what could be causing all the trouble as all the parts I've put on the newer board are all from digikey, mouser or hifi collective and within spec.
Been watching Uncle Doug videos on YouTube and a new copy of Morgan Jones'
"Valve Amplifiers" just arrived in the mail so I'll get to the bottom of this sooner or later!
I'm looking at things that were already in the amp when I got it. One thing is the choke. Researching Mudchute's build I find he used the Edcor CXC150-10H-300mA which shows 72 ohms of dc resistance where as George recommends a Triad C-14X specifically for the 150 ohms. Am I reading the specs right or possibly not considering other things that make this Edcor choke suitable?
Also the large, off board Clarity Cap tests ok in my little tester but I may just pull it to test since it's not a must for it to be there.
I think the choke is OK - more resistance means more voltage drop, so if your B+ is acceptable, the choke is acceptable. The choke in my TSE rigged for 801's is about eighty ohms.
If you look at the thread about removing mosfets from the TSE, about one or two pages into it, one of the forum members describes how to bypass the mosfets. This might allow you to get the amp running and isolate the issue to just the mosfets or see if there are still other issues.
Win W5JAG
If you look at the thread about removing mosfets from the TSE, about one or two pages into it, one of the forum members describes how to bypass the mosfets. This might allow you to get the amp running and isolate the issue to just the mosfets or see if there are still other issues.
Win W5JAG
I have 2 boards and there the same, hole on 1 side. On my working unit the hole's vacant
Problem with TSE
Hello,
I don't know if the problem is solved or still there. I will post one more possibility. I do not know if it will help in any way but I came across the problem of only one channel working at a time. Tried everything but nothing worked. Finally realized that jumper wires that I put at jumpers (at pads 3 to 4 and pads 5 to 6, I may be wrong as I am just trying to remember exactly) were too thin and were not enough for current. I changed them to thicker wires and both channels came alive.
This may not fir the problem you are having but give it a shot if your jumper wires are thin.
Good Luck.
Hello,
I don't know if the problem is solved or still there. I will post one more possibility. I do not know if it will help in any way but I came across the problem of only one channel working at a time. Tried everything but nothing worked. Finally realized that jumper wires that I put at jumpers (at pads 3 to 4 and pads 5 to 6, I may be wrong as I am just trying to remember exactly) were too thin and were not enough for current. I changed them to thicker wires and both channels came alive.
This may not fir the problem you are having but give it a shot if your jumper wires are thin.
Good Luck.
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