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Old 22nd April 2012, 08:57 PM   #631
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I'd say go over every connection and component. It can't hurt and you might get lucky. I had a fair bit of debugging on mine to get it absolutely quiet, but then it was quiet.

A few pics would help us to help you too, maybe go back through this thread and look at my pics and it might help jog something? You'll see I had issues!!

I can't get to check mine tonight, but I'll open it up tomorrow night and check voltages. I have mine wired with either direct input for MM or through a step up for MC. I'm using MM at the moment as my MC just went for a retip - so I'm using mine exactly as you are.

Fran
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Old 22nd April 2012, 09:35 PM   #632
Salas is offline Salas  Greece
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See mainly Vgk on upper tubes and input DC. Those two areas look fishy in Revmen's IMHO.
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Old 23rd April 2012, 12:52 AM   #633
RevMen is offline RevMen  United States
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I just got it all grounded and put together. When I turned it on, something went POP. I'm letting it sit for a while before I open it back up.

I might have to rethink how I'm doing this and go back a few steps. Maybe I should use 2 chassis so I can have plenty of space to spread out this circuit.

I attached a few pictures from the build process.
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File Type: jpg IMG_20120421_150408.jpg (491.5 KB, 161 views)
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Old 23rd April 2012, 01:05 AM   #634
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Something I find helpful - maybe you have done this already. I print out the sch and go through each and every connection, and tick them off on paper one by one to make sure its ok. One colour pen for left and another for right.

You build like me - its a bit messy - so its kinda hard to easily find something missing afterwards. The sch and pen has been my friend on many occasions!!

I hope to get a chance tomorrow night to take measurements for you.

Fran
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Old 23rd April 2012, 03:19 AM   #635
Salas is offline Salas  Greece
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Its a spiral like a galaxy...Very individualistic. Just make sure it is drained from HV each each time you tweak. Safety first.
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Old 23rd April 2012, 04:17 AM   #636
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Wow that is a story to tell!
I my previous life as an inspector I would step outside the door when they powered up the gear for the first time. Only once did I see fire come out the door. I recommend a face shield
DT
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Old 23rd April 2012, 04:32 AM   #637
RevMen is offline RevMen  United States
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Quote:
Originally Posted by woodturner-fran View Post
Something I find helpful - maybe you have done this already. I print out the sch and go through each and every connection, and tick them off on paper one by one to make sure its ok.
That's actually exactly what I do. I use a highlighter and highlight each connection after I verify that it's there. It won't hurt to go back over it, though.

I think I figured out what happened. The leads from Q1 on the SSHV board weren't clipped short enough, so they made contact with the bottom plate of the chassis. When I turned it on... pop. Nothing looks burned, but 345 V are going into the SSHV and only 6.4 are coming out. I'm pretty sure I burned up Q1.

I'll try to pull it off the board tomorrow and replace it. Unsoldering a 3-pin package like that is so hard. If anyone has any tips I'd be glad to hear them.
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Old 23rd April 2012, 05:25 AM   #638
Salas is offline Salas  Greece
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If there is weird reading on TP points then Q1 (CCS cascoding Mosfet) could have gone. But if there is normal reading there, it could had hit something further down. So check first. Use wick and/or desoldering pump. Some flux would help the wick if you got any in liquid form or paste.
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Old 23rd April 2012, 07:15 AM   #639
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Quote:
Originally Posted by RevMen View Post
<snip>

I'll try to pull it off the board tomorrow and replace it. Unsoldering a 3-pin package like that is so hard. If anyone has any tips I'd be glad to hear them.
A dentist would break it up into pieces and pull each root separately. I have cut the legs off op-amps, you cannot get them all hot at once without hot air. Once each leg is hot you can push it through with a tooth pick.

DT
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Old 23rd April 2012, 08:54 PM   #640
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So I checked your voltages against mine and all yours check out AOK except:

grid of V1 - I get ~1-3mVDC there
grid of V2 - I get absolutely flat 0VDC

My B+ is a little lower than yours, about 275-280V out of the shunt, so all my voltages are a little lower than yours, but the proportion is exactly the same.

I think you need to look at the voltage on the input grid in particular, then after that the layout.

Fran
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