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kgst


kevin gilmore
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All it's missing is the steam whistle....     :D          :wub:

Maybe if I crank up the current regs I could get some steam out of the vents. :wacko:

I'm looking forward to seeing it all lit up. As you may have gathered, I don't rush these things, so I'll aim for Christmas and get some pics posted. (This Christmas!!!)

 

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Thanks! Hmmm, hadn't considered motorising it.

No bending involved. They're just 10mm, end feed, 90 degree joints, used in plumbing. I just loved the shape of them, plus I figured they'd stop too much dust getting inside the chassis whilst letting some heat out. Brass block was drilled to same diameter, joints push fit and epoxy glue to fix. I dismissed soldering them in as tidying up the solder joints on the top side would have been a nightmare.  I polished the parts with a buffing wheel on my pillar drill before gluing, and again when the piece had set

‌Insanity "And what about fingerprints on that copper? Only touch with white gloves?"

Yep, a bit of a problem! Wiring the top to the B+ would solve that. (Only joking folks)

Edited by valve5425
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  • 3 weeks later...

About 3 weeks ago, Joe reported his PSU of KGST blowout twice. After discussion through FB, I suggested reconstructing the whole thing by a skillful someone. I recommend the man, Getpointlee, to take the job. Getpointlee, once a  audio dealer and a owner of audio manufacturing, live in Taipei, Taiwan. You may be interested in his blog(http://getpointlee.blogspot.tw/) . Another local DIYer provided a new PSU board for this whole new reconstructing. There are about 3 to 4 Diyers in Taiwan concern the progress of the problem that Joe met. We constantly discussed on the local forum or on the FB through private message.

Unfortunately, It blowed up again!

IMG_7680.jpg

First blow is the bias parts, then the positive rail patrs. 

Very Very strange, right?

After detailed check, Getpointlee found the problem may caused by the arc between the TP and the negative output rail. as below picture~
IMG_7676.jpg

The distance between the TP and the negative rail output line is just only 1mm, but the voltage between theses is almost 1000V! One mm is enough or not, could be a issue to discuss. However, no one here would like to have third blow again. So, for the safety issue, Getpointlee recommend the mod as below~
IMG_7682.jpg

Wish these information help your guys to know that the HV PSU blowup may cause by the arc between the TP and negative rail output.

 

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7 hours ago, Peleus said:

 

After detailed check, Getpointlee found the problem may caused by the arc between the TP and the negative output rail. as below picture~
IMG_7676.jpg

The distance between the TP and the negative rail output line is just only 1mm, but the voltage between theses is almost 1000V! One mm is enough or not, could be a issue to discuss. However, no one here would like to have third blow again. So, for the safety issue, Getpointlee recommend the mod as below~

 

Your board seems filled with flux residue ... did you, or the skilled someone, clean the boards before use?

The soldering seems like it could be enhanced a bit also - might be the light and how the picture was taken ...

Edited by sorenb
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4 hours ago, sorenb said:
 

Your board seems filled with flux residue ... did you, or the skilled someone, clean the boards before use?

The soldering seems like it could be enhanced a bit also - might be the light and how the picture was taken ...

So.....What do you mean?

The fact was there is two time blowup of the PSU. 

Did the layout cause the blowup in some unknown situation?

That is the issue we really care about. Am I clear for you? 

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It was actually my amp. I had little experience of building high voltage things. After the first blown PSU, I contacted Peleus. Peleus was kind to help me and introduced a experienced technician to build the amp for me. After two days of run-in. The positive rail and the bias part blown again with very loud sound and light. The weather was very humid recently (rainy days and I live beneath a hill). I don't know if it was the reason of the short of the negative and the bias rail. 

There is no solder, no flux between the TP of the bias and the negative rail. The white sandy smoke around the TP and the short negative rail was more like something left by heat. The upper right corner of the TP was blown away with negative rail having two small dot of melted copper wire.After discussion on the local forum, we conclude it may caused by arcing between rails.

It may because of the PCB quality, the weather, or something we don't know. The PSU just end up like this so the mod of the board was to eliminate any chance of arcing happening again.

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15 minutes ago, spritzer said:

Humidity and the PCB quality could be an issue here along with dust.  The solder resist some manufacturers use is a bad joke and will not insulate much. 

what would be a recommended way of cleaning a pcb from flux residue? do you test your pcbs with an isolation tester?

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21 minutes ago, n_maher said:

Get the purest isopropyl alcohol that you can find in a decent quantity and several sacrificial tooth brushes.  Lather, rinse, repeat until clean.  Manage the waste appropriately.

Thanks....I've use this one ...doesn't tell what the magic solution comprises, but it surely smells like isopropanol ....seems to work ok

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2 hours ago, sorenb said:

Thanks....I've use this one ...doesn't tell what the magic solution comprises, but it surely smells like isopropanol ....seems to work ok

I wouldn’t use it, has to be at least 98-99% pure isopropyl alcohol as Nate has alluded to. The lower graded solution probably would do no harm it just wouldn’t have the cutting capability of a pure grade solution, hence you end up doing more passes to clean of the flux gunk.

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