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i'm on a roll... the kgsshv


kevin gilmore
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3 hours ago, Laowei said:

One source I used. Great to deal with.

https://www.ebay.com/itm/PTFE-wire-Alpha-5854-7-or-equiv-20-ga-Mil-16878-4-silver-plated-10-feet/292416116301

Many other wire gauges, solid or stranded available by seller. Do a search of his other items.

I second this ebay seller as I initially purchased from him.  He has large variety of colors.

The hook-up wire I used is multi-stranded PTFE #22 for all but the earth where I used #18.

Another source that sells per foot that I also used is Remington Industries either directly through their website or through amazon (www.remingtonindustries.com).

There is also Bulk Wire (bulkwire.com) but I haven't purchased from them.

 

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  • 2 weeks later...
  • 4 weeks later...

It took me 7 years to build my second kgsshv, or so I thought, and no cigar as I powered this one up. I have a problem with the positive, HV rail in the power supply: I measured ~10V instead of +450V. I need some help to troubleshoot.

Couple of things:

1) when powering on, after long discharge time, I get sparks in the neighborhood of the 680uF/450V caps for that rail. This lasts for a second, and goes away. First time i switched off right away, but when I turned amp back on soon after, no problem... if one waits more than 30minutes, then small sparks come back on first “ignition”. No smoke.
1b) After close visual inspection, two legs of the bridge diode for this side of the PS are a bit darker than the others (bronze close to pcb rather than silver). These are the legs connected to the top plane of the pcb. Using a multimeter, diodes seem to be ok for allowing current flow in one direction and not the other (using diode checker on multimeter). There seemed to be missing copper pads top of board (if there was any). Above the 0 in the rev0.9.

1c) I confirmed the two legs, one per diode, are not connected to top plane. Did I vaporize copper at first power up, or was there even any (I assembled the ps years ago, never checked before assembly as I solder from bottom face)

2) output of transformer measures 493V AC. (Both sides)

3) negative rail of PS OK (-453V out of PS).

4) PS board is regular size (not mini), rev v0.9.

Any help would be greatly appreciated. Thanks.

178E6685-B1F7-43A2-9488-A8A2BA922621.jpeg

Edited by eslover
Added details 1b and 1c
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  • 1 month later...

2T0A5573_HC_edit.thumb.jpg.95abd26245380797acae533d1631029f.jpg

On 11/1/2020 at 10:50 PM, hhobeika said:

Here is a picture of the inside.  There is a limit on the file size I can upload so I had to dramatically shrink it and compress it to be able to post it.

I had looked at this closer awhile back, and noticed what looks like a wire loom or separator down on the floor of the amp by the output jacks, to hold the output lines in order. Is this something that you made, or is commercially available? I did a quick search at Mouser but didn't turn up anything like this. Thanks!

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22 hours ago, Pars said:

2T0A5573_HC_edit.thumb.jpg.95abd26245380797acae533d1631029f.jpg

I had looked at this closer awhile back, and noticed what looks like a wire loom or separator down on the floor of the amp by the output jacks, to hold the output lines in order. Is this something that you made, or is commercially available? I did a quick search at Mouser but didn't turn up anything like this. Thanks!

Those are Nylon Caterpillar Grommet Strips repurposed as wire spacers.  I cut them to the number of slots needed.  Each is held in place using a tie wrap and a wire tie mount.  You can find them at Mouser by searching under "grommet strip".  I had some lying around so I can't give a specific part number but they come in various sizes.

a5ngee.jpg

 

I only used them on the output wires to keep them spaced in order to minimize the capacitance.

More photos of my build at the Dropbox link below:

https://www.dropbox.com/sh/4ox0xh7s1aiw5cb/AACdu5DpeRyeFuINloC8HkRFa?dl=0

Hope this helps.

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Thanks for replying. Very clever use of the grommet strips. Once you brought them up, I recall seeing these used for grommet holes. I would have never thought of using them for this purpose. Well, maybe if I had some on hand, a light bulb would have gone on...

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My 500V offboard kgsshv currently has two rev 0.4 amp boards and a rev 0.6 power board.

I am looking to swap one of the rev 0.4 amp boards to a rev 0.5 board.

When I change from a rev 0.4 to a rev 0.5 amp board, I will need to:

1) Not cross the 50K resistors

2) Not cross the 1n914 diodes

3) Not flip the O+ and O- bias outputs

Is this correct and also is there anything else I need to do when going from rev 0.4 to rev 0.5 boards?

Thanks y'all!

Edited by powertoold
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10 hours ago, powertoold said:

My 500V offboard kgsshv currently has two rev 0.4 amp boards and a rev 0.6 power board.

I am looking to swap one of the rev 0.4 amp boards to a rev 0.5 board.

When I change from a rev 0.4 to a rev 0.5 amp board, I will need to:

1) Not cross the 50K resistors

2) Not cross the 1n914 diodes

3) Not flip the O+ and O- bias outputs

Is this correct and also is there anything else I need to do when going from rev 0.4 to rev 0.5 boards?

Thanks y'all!

For rev 0.4 which is the one I built, it was either to cross the 50k resistors or the 1N914 diodes to correct the reversed feedback, not both.  That also resulted in the output polarity O+ and O- being reversed.

I am not sure if it was corrected in rev 0.5 but it should be easy enough to check by comparing the PCB traces between rev 0.4 and rev 0.5 if you have both.

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1 hour ago, hhobeika said:

I am not sure if it was corrected in rev 0.5 but it should be easy enough to check by comparing the PCB traces between rev 0.4 and rev 0.5 if you have both.

I see, thanks! I'm not very knowledgeable with circuits, so I'm just making sure my thoughts are correct before something blows 😅

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Just in case anyone needs this for future reference, I've posted the tracings of the 0.4 and 0.5 offboards. The difference is shown near the purple dot.

The front side of the boards are identical to me. Also, there's no need to cross the diodes or the 50K resistors on the 0.5. This means there's no need to flip the 0+ and O- as well.

1401653780_20210124_1812092.thumb.jpg.86459307ab8b0bb88012d67eb00c200d.jpg

594661569_20210124_1736423.thumb.jpg.59cf4b40c90def2f0e302ad14fd2ff4f.jpg

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  • 3 weeks later...

Hopefully this helps someone in the future.

My 500V offboard KGSSHV (running at ~10mA, 100R for the current adjusting resistors) developed some grainy distortion on the left channel (only with some low bass reverb frequencies). After replacing all sorts of parts, I found that the distortion was due to the IXYS transistors.

I had bought 2x IXTP01N100D from Mouser in June 2020 and 4x in Jan 2021. It turns out both of these sets were "bad" parts, symptoms below:

1) Offset voltage on left channel started at around +35V and drift upwards to around +70V

2) There was no way to lower the offset voltage, as the trimpot was maxed out

3) The sound was a bit metallic from the left channel

4) The volume was a bit lower than normal

Fortunately, spritzer sold me some of his old stock IXTP01N100D, and after replacing the new IXYSes with spritzer's old stock IXYS, all of the symptoms went away, and the amp sounded "normal" again.

With the old stock IXYS:

1) My offset voltage started around -35V and then drifted towards 0V

2) Amp seemed cooler to the touch

BTW, I think the 500V KGSSHV offboard at 10mA is the best pairing for the 007 mk1.

Edited by powertoold
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3 hours ago, Pars said:

Are Mouser or IXYS going to do anything about it, or have they been told?

I don't have a means to test the IXYS transistors I got from Mouser. The Jan 2021 ones I got from Mouser are lot TS1811 S23728.

If y'all got a 500V with IXYS and offset voltage problems, perhaps you have these problematic transistors as well. The amp works and all. It just doesn't sound or measure like what it's supposed to.

Edit: on closer inspection, it seems the parts I bought in June 2020 and Jan 2021 are the same lot number.

Edited by powertoold
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