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Author Topic: Tentec Titan 425 Blowing 20 Amp Fuses  (Read 14723 times)
N1UK
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Posts: 1401




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« Reply #45 on: May 17, 2013, 05:50:19 AM »

Since I took that picture I l flowed some more solder down because I thought that it was a bit thin as well.

I used solder wick and maybe you are seeing the slightly serrated edge of the solder wick catching the light of the camera flash.  The solder wick on the top trace is really overkill because there was only a small area of trace burnt away but I wanted to make doubly sure.............................

OK I added more solder.  Here it is

http://img689.imageshack.us/img689/8674/dscn8804u.jpg


Mark N1UK
« Last Edit: May 17, 2013, 06:11:55 AM by N1UK » Logged
KE3WD
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Posts: 5694




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« Reply #46 on: May 17, 2013, 08:26:30 AM »

I knew that was a piece of Solder Wick from the first pic, and as I said before, it looks just fine. 

I use Solder Wick to repair broken traces like that quite a bit, works well unless the circuit is involved with frequencies higher than around 200 MHz where enlarging such a trace may cause excess capacitor detuning.  That, of course, is not going to be a problem in this PS board.  The addition of the extra copper from the Solder Wick should be very ample enough Current handling there. 

Touching it up again to make it prettier didn't hurt anything. 

Move on.


73
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N1UK
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« Reply #47 on: May 17, 2013, 08:36:02 AM »

Quote
Move on.

I am moving..hi hi . Fixed plumbing this morning and now I want to hook up the variac and wind it up a little to check everything before I replace the pcb.

I will repopulate the pc later today. and wire it back in and then variac test the psu assembly without the rf deck connected.

Maybe time to add a whole house surge protector as well. I have two 200 amp panels. So it will be two surge protectors. Any advice on a good one to fit?


Mark N1UK
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N1UK
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Posts: 1401




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« Reply #48 on: May 17, 2013, 02:55:35 PM »

I hooked up a variac to the transformer primary, bypassing the soft start circuit and on/off relay and I was able to apply approximately 25VAC and see 214 VAC on the HV winding. So so far so good. I will rebuild the HV bridge rectifier and smoothing board and wind up some voltage onto that next.

Here is the schematic for the PSU. Mine is slightly different to this. Soft start resistor is 10 ohms, and the combined rectifier smoothing pcb is different but the main details are the same.

http://www.mediafire.com/view/?d8117dib1zyjqt5

Mark N1UK
« Last Edit: May 17, 2013, 03:54:49 PM by N1UK » Logged
K8AXW
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Posts: 3722




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« Reply #49 on: May 17, 2013, 06:08:39 PM »

Mark:  Lookin good!  I have bridged open traces with wire and solder before but have never used solderwick.  Great idea.  Perhaps that's why I never picked up on it.
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KC4MOP
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Posts: 731




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« Reply #50 on: May 18, 2013, 03:28:28 AM »

Mark:  Lookin good!  I have bridged open traces with wire and solder before but have never used solderwick.  Great idea.  Perhaps that's why I never picked up on it.

You're lucky with the solder wick. I never had good success with that. I like the Solder Sucker approach.
I hope you get that beast working. It's a power house amplifier that will happily give a little beyond QRO power.
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N1UK
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« Reply #51 on: May 18, 2013, 11:33:25 AM »

Quote
You're lucky with the solder wick. I never had good success with that. I like the Solder Sucker approach

I used the solder wick as a copper conductor, laid down on the board to repair a blown trace.

I much prefer my solder sucker when it comes to removing solder and components.

Update....The new board is built and wired in. I am applying approx 60 VAC in from the variac and have 600 VDC on the output of the board. I will let is soak for a while.

http://img829.imageshack.us/img829/8499/dscn8831a.jpg

http://imageshack.us/a/img59/1062/dscn8829.jpg



Mark N1UK
« Last Edit: May 18, 2013, 11:44:50 AM by N1UK » Logged
KE3WD
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Posts: 5694




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« Reply #52 on: May 18, 2013, 12:39:24 PM »

Don't view the available desoldering tools as an either/or situation.  

Have both available.  

The Solder Sucker is great for the things it can do well, likewise the Solder Wick has its uses for certain solder removal and cleanup tasks, too.  


73
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N1UK
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« Reply #53 on: May 18, 2013, 02:48:05 PM »

Can I hook up the rf deck and just wind the variac on the psu a little to check for rf deck problems? Can I do this with with and without the tubes in place?

Mark N1UK

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K8AXW
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« Reply #54 on: May 18, 2013, 04:56:19 PM »

I'd take the tubes out, make sure the dangling anode leads don't touch anything, and then use the variac to bring the power supply up to the rated voltage.

I wouldn't bring the PSU up with the tubes in place, unless it uses a separate filament transformer.

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N1UK
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« Reply #55 on: May 18, 2013, 05:26:33 PM »

Can that damage the tubes?

Mark N1UK
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KC4MOP
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« Reply #56 on: May 18, 2013, 05:49:12 PM »

Can that damage the tubes?

Mark N1UK
Bringing up the HV supply only on the Variac is a safe approach. The variac will not like bringing the entire amplifier up to full voltage. This is a 220 volt variac?
Right now it is best to leave the tubes out of the picture until you have the P.S. happily making HV again.
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N1UK
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« Reply #57 on: May 18, 2013, 06:45:47 PM »

I am using a 115V variac for now. I could run it into a step up transformer if required but I only ran the AC input up to about 70 V RMS


I did run about 700 V of HV into the rf deck earlier this afternoon so there are no hard short circuits in there.


I have the power supply power supplying the low voltage into the amp right now. I will change the tubes tomorrow and power it all up I think. I suspect the old tubes of maybe being soft and arcing over inside on random occasions.


Mark N1UK
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K8AXW
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« Reply #58 on: May 18, 2013, 09:23:18 PM »

I can't say with authority if bringing up the amp with a variac with the tubes in place would be harmful to the tubes..... I just don't know exactly what happens when the HV is brought up with the tube filaments at less than full voltage/full emission. 

No doubt there will be others here than can answer that question.  If it was me I'd rig it to bring up the HV to full voltage with the variac sans tubes.  If all was OK, then I'd MAKE SURE THE HV IS BLED OFF and then reinsert the tubes and then fire it up normally.

If it blows, then you'll know it's the tube(s).   Embarrassed
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