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Old 9th March 2017, 12:38 PM   #51
CalTurk is offline CalTurk  Germany
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Quote:
Originally Posted by w5jag View Post
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
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.
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Old 9th March 2017, 12:40 PM   #52
CalTurk is offline CalTurk  Germany
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Quote:
Originally Posted by mkane77g View Post
That's just another mounting point to accommodate different size caps?
I considered that but it's only on the one side.
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Old 9th March 2017, 01:02 PM   #53
w5jag is offline w5jag  United States
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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
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Old 9th March 2017, 01:05 PM   #54
CalTurk is offline CalTurk  Germany
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Quote:
Originally Posted by w5jag View Post
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

I remeber reading that. I'll revisit the thread and try it out.
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Old 9th March 2017, 01:09 PM   #55
CalTurk is offline CalTurk  Germany
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Win, when you write "Have you tried that channel that shows proper voltages to see if it works properly?" Do you mean simply pulling the output tube for that channel??
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Old 9th March 2017, 01:13 PM   #56
CalTurk is offline CalTurk  Germany
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I guess I would also pull the input for that channel too.
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Old 9th March 2017, 01:16 PM   #57
w5jag is offline w5jag  United States
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I meant the bold approach of putting all the tubes into that side, putting an input signal to it, connecting up a test speaker, and seeing if it plays.

Win W5JAG
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Old 9th March 2017, 01:23 PM   #58
w5jag is offline w5jag  United States
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I think you would have to remove the mosfet we already suspect is shorted, to try the bypass trick.

But it seems worth a shot.

Win W5JAG
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Old 9th March 2017, 04:42 PM   #59
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Quote:
Originally Posted by CalTurk View Post
I considered that but it's only on the one side.
I have 2 boards and there the same, hole on 1 side. On my working unit the hole's vacant
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Old 3rd April 2017, 02:15 AM   #60
humayun is offline humayun  United States
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Default 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.
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