Date   

Re: strange electrical issue - anyone have any knowledge of what to do.

Don Curry
 

The 4700mf 25 volt cap looks like to it has leaked out badly along with 2 other caps nearby C3


Re: strange electrical issue - anyone have any knowledge of what to do.

Christopher Erickson
 

The brown stuff at the base of the large caps is a potting compound to protect them a bit from 60hz/120hz vibrations.  I assume at one point they had a problem with cap failures because vibration from the big transformer was weakening the bonds between the cap electrodes and their thin internal plates.
 
I don't see any obvious smoking guns in that pic.  Other than being a 25-year-old circuit board design and a rather cheap circuit board.
 
 
-Christopher Erickson
Observatory engineer
Summit Kinetics
Waikoloa, HI 96738
www.summitkinetics.com
 


From: ap-gto@... [mailto:ap-gto@...]
Sent: Saturday, October 21, 2017 8:15 AM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

Brown stain as on the board. Like I use to tell my helpers, it ain’t good letting the smoke out…..

 

-Steve

 

From: ap-gto@... [mailto:ap-gto@...]
Sent: Saturday, October 21, 2017 2:13 PM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 

 

The three central caps look like they have a dark brown stain but maybe shadow? Sometimes the bottom helps reveal what you may not see from above. I’m guessing you unmounted the board?

 

-Steve

 

 

From: ap-gto@... [mailto:ap-gto@...]
Sent: Saturday, October 21, 2017 1:43 PM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 

 


Woody

I placed a picture (500KB) of my Printed circuit board (pcb) in the files section for my Pyramid PS15KX.

https://groups.yahoo.com/neo/groups/ap-gto/files/Pyramid-PS15KX.jpg

I will remove picture upon request or after Christopher gives us his results on problem/solution.

The 3 black wires in center are all connected to a common ground on pcb.

Bottom black wire goes to negative screw terminal on front.
Middle black wire goes to cigarette outer case (negative side) which also contacts the chassis.
Top black wire goes to center-tap of transformer.

Jimmy


Virus-free. www.avg.com


Re: strange electrical issue - anyone have any knowledge of what to do.

Steve Reilly
 

Brown stain as on the board. Like I use to tell my helpers, it ain’t good letting the smoke out…..

 

-Steve

 

From: ap-gto@... [mailto:ap-gto@...]
Sent: Saturday, October 21, 2017 2:13 PM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 

 

The three central caps look like they have a dark brown stain but maybe shadow? Sometimes the bottom helps reveal what you may not see from above. I’m guessing you unmounted the board?

 

-Steve

 

 

From: ap-gto@... [mailto:ap-gto@...]
Sent: Saturday, October 21, 2017 1:43 PM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 

 


Woody

I placed a picture (500KB) of my Printed circuit board (pcb) in the files section for my Pyramid PS15KX.

https://groups.yahoo.com/neo/groups/ap-gto/files/Pyramid-PS15KX.jpg

I will remove picture upon request or after Christopher gives us his results on problem/solution.

The 3 black wires in center are all connected to a common ground on pcb.

Bottom black wire goes to negative screw terminal on front.
Middle black wire goes to cigarette outer case (negative side) which also contacts the chassis.
Top black wire goes to center-tap of transformer.

Jimmy


Re: strange electrical issue - anyone have any knowledge of what to do.

Steve Reilly
 

The three central caps look like they have a dark brown stain but maybe shadow? Sometimes the bottom helps reveal what you may not see from above. I’m guessing you unmounted the board?

 

-Steve

 

 

From: ap-gto@... [mailto:ap-gto@...]
Sent: Saturday, October 21, 2017 1:43 PM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 

 


Woody

I placed a picture (500KB) of my Printed circuit board (pcb) in the files section for my Pyramid PS15KX.

https://groups.yahoo.com/neo/groups/ap-gto/files/Pyramid-PS15KX.jpg

I will remove picture upon request or after Christopher gives us his results on problem/solution.

The 3 black wires in center are all connected to a common ground on pcb.

Bottom black wire goes to negative screw terminal on front.
Middle black wire goes to cigarette outer case (negative side) which also contacts the chassis.
Top black wire goes to center-tap of transformer.

Jimmy


Re: strange electrical issue - anyone have any knowledge of what to do.

jimmyjujames
 


Woody

I placed a picture (500KB) of my Printed circuit board (pcb) in the files section for my Pyramid PS15KX.

https://groups.yahoo.com/neo/groups/ap-gto/files/Pyramid-PS15KX.jpg

I will remove picture upon request or after Christopher gives us his results on problem/solution.

The 3 black wires in center are all connected to a common ground on pcb.

Bottom black wire goes to negative screw terminal on front.
Middle black wire goes to cigarette outer case (negative side) which also contacts the chassis.
Top black wire goes to center-tap of transformer.

Jimmy


Re: strange electrical issue - anyone have any knowledge of what to do.

Joel Short
 

Woody, I'm curious to know what your new power supply is, the one with powerpole connectors?
joel


Re: strange electrical issue - anyone have any knowledge of what to do.

Christopher Erickson
 

That schematic shows an LM723 adjustable voltage regulator IC as the heart of the design.
 
The LM723 was announced in the mid-70's.  It is the poster child for old-school style power supply designs.
 
 
Did any of the capacitors look swollen?
 
Does anyplace on the circuit board look a bit burned or brownish?
 
Do any of the big TO-3 style power transistors or the metal around them look bluish or brownish?
 
 
 
-Christopher Erickson
Observatory engineer
Summit Kinetics
Waikoloa, HI 96738
www.summitkinetics.com
 


From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 4:50 PM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

Woody

update but no fix

I also have a Pyramid PS-15KX which I occasionally use but mostly run my 900GTO on battery.

Schematic located at

http://www.repeater-builder.com/pyramid/pdfs/PS15K.pdf

Removed cover

Measured DC voltage from terminal lug on green protective wire that is connected to chassis to

negative (-) screw terminal on front.  Voltage was 0 volts
positive (+) screw terminal on front.  voltage was 14.2 volts

Some power supplies float the negative and positive 13 V DC from chassis
This power supply connects the negative DC to chassis.

The negative side of cigarette jack is physically connected to chassis.

I read less than 1 ohm from chassis to negative screw terminal on front
I read less than 1 ohm from chassis to negative side of cigarette jack

This is about as far as I can go on troubleshooting this problem.

Looking forward to Christopher's findings.

Jimmy

Virus-free. www.avg.com


Re: strange electrical issue - anyone have any knowledge of what to do.

Woody Schlom <woody@...>
 

Christopher,

 

No, don’t worry about that.  I’ll send it later today.  And if you’re able to fix it, I’ll send you return postage via PayPal.

 

I’m rather curious to find out what’s wrong with it too – and whether or not just a couple are bad, or whether they have a serious QC problem.  I’ve got to say, it sure looks nice on the inside to me.  They even painted all the bolts and nuts to prevent them loosening.

 

If/when you figure out what’s wrong with it, I can look up the purchase date through Amazon.  That might (or might not) indicate when it was made.  I think it’s about 2 years old.  My other one (identical model) is probably 4 or 5 years old and it’s just fine.

 

Good luck with this thing.

 

Woody

 

From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 2:56 PM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 

 

Woody, what if I paid YOU to ship me that power supply?

 

If there is a potential problem with newer Pyramid power supplies because they are cutting back on QC costs or something, a lot of people could benefit from having me or AP carefully looking at your bad power supply.

 

 

-Christopher Erickson
Observatory engineer
Summit Kinetics

Waikoloa, HI 96738
www.summitkinetics.com

 

 


From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 11:46 AM
To: ap-gto@...
Subject: Re: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

It might however shed some light on problems that others are having. We have one person who wiped out two laptops, might be the same issue.

Rolando

 

 

 

-----Original Message-----
From: 'Woody Schlom' woody@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Fri, Oct 20, 2017 4:36 pm
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 

Christopher,

 

Thanks and I can tell you're dying to diagnose and fix this thing.  But it's just not worth it.

 

It's much heavier and larger than similar switching power supplies and I no longer value the automotive cigarette lighter socket.  So I'll just toss it and use the new switching PS I already bought as a replacement.  The new one is smaller, lighter weight, has two built-in PP connectors and has three times the amperage.

 

Thanks again,

Woody

 

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 2:27 PM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 

Sounds like there is a short in the power supply electronics to the frame ground.

 

Could be a wiring problem, a circuit board problem, a transistor insulator problem or a screw fastener problem (oversized screw head, too long, etc,)

 

My speculation is that the most likely cause is a mica power transistor insulator wafer is either missing or otherwise not working as designed for some reason and the case of the power transistor is directly connected to the power supply's frame ground.

 

Use a large USPS Flat Rate Priority Mail box to send it to me and I can find out for sure.  And pay another $15 to have me ship the repaired power supply back to you.

 

 

-Christopher Erickson
Observatory engineer
Summit Kinetics

Waikoloa, HI 96738
www.summitkinetics.com

 

 


From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 9:38 AM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

Jimmy,

 

Thank you for this.  I'm no electrical engineer, but I think I ran the test you suggested.

 

1) I set my meter to read DC volts.

 

2) I turned the PS ON.

 

3) I put the red meter lead on the red +13.8v DC screw terminal on the front of the PS, and the black meter lead on the chassis ground screw.  The meter read -11.72v,  not 0.

 

4) I put the red meter lead on the black -13.8v DC screw terminal on the front of the PS, and the black meter lead on the chassis ground screw.  The meter read -25.58v,  not 0.

 

So it looks as if I have a definite problem.  I don't see any obvious stray wires or strands.

 

Could this be caused by a bad cap or two?  Or am I just wasting my time with this thing?

 

Woody

 

 

 


I remember one member had warm cables back last year(?)

His DC power supply +13.8 V DC lug was touching the power supply chassis.

I think the current loop would be from
 +13.8 V DC to chassis to protective ground (green wire) to Desktop computer protective ground.
 The Desktop pc protective ground is connected to DC ground inside PC
 DC ground wire connects CP3/4 and then to the negative lug on 13.8V DC power supply completing the ground loop.
 
 With a DC voltmeter,
 I would check voltage from power supply chassis to it's negative 13.8 Volt lug at front and
 then chassis to positive lug on front of power supply.  Both should be 0 volts.
 
 The member from last year saw -13.8 volts from power supply chassis to negative lug on front of power supply.
 That means his +13.8 volt lug on front was shorted to chassis.
 
 As always, I may be! wrong again.
 
 Jimmy
 

 

Virus-free. www.avg.com

 


Re: strange electrical issue - anyone have any knowledge of what to do.

jimmyjujames
 

Woody

update but no fix

I also have a Pyramid PS-15KX which I occasionally use but mostly run my 900GTO on battery.

Schematic located at

http://www.repeater-builder.com/pyramid/pdfs/PS15K.pdf

Removed cover

Measured DC voltage from terminal lug on green protective wire that is connected to chassis to

negative (-) screw terminal on front.  Voltage was 0 volts
positive (+) screw terminal on front.  voltage was 14.2 volts

Some power supplies float the negative and positive 13 V DC from chassis
This power supply connects the negative DC to chassis.

The negative side of cigarette jack is physically connected to chassis.

I read less than 1 ohm from chassis to negative screw terminal on front
I read less than 1 ohm from chassis to negative side of cigarette jack

This is about as far as I can go on troubleshooting this problem.

Looking forward to Christopher's findings.

Jimmy


Re: Latest V2 driver

Ray Gralak
 

I knew there was a discussion, but a search of the forum for
"5.10.02" yielded and "driver" yielded nothing recent. Thanks.
Here you go:

https://groups.yahoo.com/neo/groups/ap-gto/conversations/topics/58920


-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro: http://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: http://www.gralak.com/apdriver
Author of PulseGuide: http://www.pulseguide.com
Author of Sigma: http://www.gralak.com/sigma


-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 2:29 PM
To: ap-gto@...
Subject: [ap-gto] Re: Latest V2 driver



I knew there was a discussion, but a search of the forum for
"5.10.02" yielded and "driver" yielded nothing recent. Thanks.


Re: strange electrical issue - anyone have any knowledge of what to do.

Christopher Erickson
 

Pyramid has always made great stuff but like all electronic product companies, they buy most of their electronic components from distributors and there has been a big and growing bigger problem over the past couple decades or so with counterfeit electronic components slipping into the distribution network and causing all kinds of chaos.
 
 
 
 
 
 
Even Hewlett-Packard was victimized some years ago by counterfeit components that made it into some of their products and caused millions of dollars of losses because of returns, fires and lawsuits.  And tiny companies like Pyramid don't have near the corporate resources of HP to combat getting suckered by counterfeit parts.
 
The reputation of Prolific was ruined when counterfeit Prolific serial chips flooded the market so effectively that only about 1 in 10 Prolific USB to Serial adapters on the market had a genuine Prolific chip inside.
 
The reasons behind the Samsung Galaxy Note 7 fires are complex but part of that story involves counterfeit components.
 
It's a bit premature at this point to condemn Pyramid or their power supplies until more evidence is collected.
 
If anyone has a Pyramid power supply that they think is misbehaving, I would be very interested in inspecting it to see if some kind of pattern or trend emerges.  It will cost about $15 to ship me your power supply via a large USPS Flat Rate, 3-day Priority Mail box, which is available for free at your local US Post Office.  It's unfortunate that people outside of the USA don't have access to this awesome shipping option.  Most problems I will be able to easily fix and then ship your power supply back to you.  If there is a short inside of the main transformer, the cost for repair would be more than the cost of a new replacement switching power supply.
 
Until we know more, maybe AP should start testing every Pyramid power supply before shipping them out to customers.
 
There is still a chance that all of this is a red herring too.
 
I'll share what I find out as quickly as possible.
 
 
-Christopher Erickson
Observatory engineer
Summit Kinetics
Waikoloa, HI 96738
www.summitkinetics.com
 


From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 1:06 PM
To: ap-gto@...
Subject: Re: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

Same here. Been using them in my observatory for years without problems.

Roland



-----Original Message-----
From: 'Steven Reilly' sreilly24590@... [ap-gto]
To: ap-gto
Sent: Fri, Oct 20, 2017 5:51 pm
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.



I’ve been using Pyramid 12 amp PS and they have always worked great. Not saying there couldn’t be a problem but just a data point. One on the mount and one on the dew heaters.
 
-Steve
 
 
From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 6:23 PM
To: ap-gto@...
Subject: Re: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.
 
There probably isn't a perfect solution out there.
 
Only buying quality, brand name equipment helps. As would having a good multimeter in your kit and knowing how to use it.

There are 12V gfci devices out there but I have not researched what might offer simple and meaningful protection for telescopes and small observatories.
 
Maybe I'll look into that.
 

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   
 
On Oct 20, 2017 12:12 PM, "'Joseph Zeglinski' J.Zeglinski@... [ap-gto]" <ap-gto@...> wrote:
 
Chris,
 
    Of course, you are correct – manufacturers would rather save $2 and leave the risk to “probability and statistics”.
I was just wondering what WE can do – invest in some kind of safety device -  for our extremely expensive investment – to protect the electronics from “whatever” is causing a ground fault. That’s without pointing a/the  finger at any specific manufacturer. This problem is just all too common.
 
    Yes, a huge copper (earth ground) stake in the ground is one simple way – but perhaps inconvenient  in portable setups.
 
Joe
 



Virus-free. www.avg.com


Re: strange electrical issue - anyone have any knowledge of what to do.

Christopher Erickson
 

I'll report on-list what I find out.
 
 
-Christopher Erickson
Observatory engineer
Summit Kinetics
Waikoloa, HI 96738
www.summitkinetics.com
 


From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 12:30 PM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

Jimmy,
 
It's a Pyramid Model: PS-15KX. 
 
You guys (particularly Roland) have shamed me into figuring out what the problem is.  So in the interest of "science" and hopefully helping others, I'll contact Christopher off-group and ship the thing to him in Hawaii and see what he can find out.
 
Woody
 
-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 3:18 PM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 

Woody

I see you still have 13.8 volts between the positive and negative terminals.

Shorted cap, possibly
May be same cap your friend replaced.

Positive terminal shorted to -11 Volts below protective ground?

or

Negative terminal shorted to -25 Volts below protective ground?

I don't understand a solution to these results.

I do enjoy troubleshooting and brain teasers.

What model PS do you have and do you know of an on-line schematic.

If not, I don't think I can help any further.

Jimmy


Virus-free. www.avg.com


Re: strange electrical issue - anyone have any knowledge of what to do.

Woody Schlom <woody@...>
 

Steve,
 
Yes I agree.  The reason I bought this one was because I already had one that works great -- and it's still working great.  But this one was "bad" out of the box. 
 
Unfortunately, I only tested its output voltage when I received it.  Voltage was 13.89v DC between the two terminals -- so I assumed everything was OK.  Months later I tried to use it at a star-party and it blew up one of my monitors.  I marked it as BAD, and then totally forgot about it -- for about 14 months.  Then recently I tried to use it and melted two power cables before I recalled the problems I'd had the last time I used it.
 
And that brings me to the present.
 
My original Pyramid continues to just plain work -- day in and day out.
 
Woody
 

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 3:51 PM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 

I’ve been using Pyramid 12 amp PS and they have always worked great. Not saying there couldn’t be a problem but just a data point. One on the mount and one on the dew heaters.

-Steve

From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 6:23 PM
To: ap-gto@...
Subject: Re: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 

There probably isn't a perfect solution out there.

Only buying quality, brand name equipment helps. As would having a good multimeter in your kit and knowing how to use it.

There are 12V gfci devices out there but I have not researched what might offer simple and meaningful protection for telescopes and small observatories.

Maybe I'll look into that.


-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Oct 20, 2017 12:12 PM, "'Joseph Zeglinski' J.Zeglinski@... [ap-gto]" <ap-gto@...> wrote:

Chris,

    Of course, you are correct – manufacturers would rather save $2 and leave the risk to “probability and statistics”.

I was just wondering what WE can do – invest in some kind of safety device -  for our extremely expensive investment – to protect the electronics from “whatever” is causing a ground fault. That’s without pointing a/the  finger at any specific manufacturer. This problem is just all too common.

    Yes, a huge copper (earth ground) stake in the ground is one simple way – but perhaps inconvenient  in portable setups.

Joe


Re: strange electrical issue - anyone have any knowledge of what to do.

Roland Christen
 

Same here. Been using them in my observatory for years without problems.

Roland



-----Original Message-----
From: 'Steven Reilly' sreilly24590@... [ap-gto]
To: ap-gto
Sent: Fri, Oct 20, 2017 5:51 pm
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.



I’ve been using Pyramid 12 amp PS and they have always worked great. Not saying there couldn’t be a problem but just a data point. One on the mount and one on the dew heaters.
 
-Steve
 
 
From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 6:23 PM
To: ap-gto@...
Subject: Re: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.
 
 
There probably isn't a perfect solution out there.
 
Only buying quality, brand name equipment helps. As would having a good multimeter in your kit and knowing how to use it.

There are 12V gfci devices out there but I have not researched what might offer simple and meaningful protection for telescopes and small observatories.
 
Maybe I'll look into that.
 

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   
 
On Oct 20, 2017 12:12 PM, "'Joseph Zeglinski' J.Zeglinski@... [ap-gto]" <ap-gto@...> wrote:
 
Chris,
 
    Of course, you are correct – manufacturers would rather save $2 and leave the risk to “probability and statistics”.
I was just wondering what WE can do – invest in some kind of safety device -  for our extremely expensive investment – to protect the electronics from “whatever” is causing a ground fault. That’s without pointing a/the  finger at any specific manufacturer. This problem is just all too common.
 
    Yes, a huge copper (earth ground) stake in the ground is one simple way – but perhaps inconvenient  in portable setups.
 
Joe
 



Re: strange electrical issue - anyone have any knowledge of what to do.

Steve Reilly
 

I’ve been using Pyramid 12 amp PS and they have always worked great. Not saying there couldn’t be a problem but just a data point. One on the mount and one on the dew heaters.

 

-Steve

 

 

From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 6:23 PM
To: ap-gto@...
Subject: Re: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 

 

There probably isn't a perfect solution out there.

 

Only buying quality, brand name equipment helps. As would having a good multimeter in your kit and knowing how to use it.

There are 12V gfci devices out there but I have not researched what might offer simple and meaningful protection for telescopes and small observatories.

 

Maybe I'll look into that.

 


-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

 

On Oct 20, 2017 12:12 PM, "'Joseph Zeglinski' J.Zeglinski@... [ap-gto]" <ap-gto@...> wrote:

 

Chris,

 

    Of course, you are correct – manufacturers would rather save $2 and leave the risk to “probability and statistics”.

I was just wondering what WE can do – invest in some kind of safety device -  for our extremely expensive investment – to protect the electronics from “whatever” is causing a ground fault. That’s without pointing a/the  finger at any specific manufacturer. This problem is just all too common.

 

    Yes, a huge copper (earth ground) stake in the ground is one simple way – but perhaps inconvenient  in portable setups.

 

Joe

 


Re: strange electrical issue - anyone have any knowledge of what to do.

Woody Schlom <woody@...>
 

OK, OK.  You've shamed me into getting to the bottom of my PS problem.  In the interest of "science" and helping others, I'll ship the thing to Christopher in Hawaii and see what he can learn.
 
Woody
 

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 2:46 PM
To: ap-gto@...
Subject: Re: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 

It might however shed some light on problems that others are having. We have one person who wiped out two laptops, might be the same issue.

Rolando




-----Original Message-----
From: 'Woody Schlom' woody@... [ap-gto]
To: ap-gto
Sent: Fri, Oct 20, 2017 4:36 pm
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.



Christopher,
 
Thanks and I can tell you're dying to diagnose and fix this thing.  But it's just not worth it.
 
It's much heavier and larger than similar switching power supplies and I no longer value the automotive cigarette lighter socket.  So I'll just toss it and use the new switching PS I already bought as a replacement.  The new one is smaller, lighter weight, has two built-in PP connectors and has three times the amperage.
 
Thanks again,
Woody
 
-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 2:27 PM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 
Sounds like there is a short in the power supply electronics to the frame ground.
 
Could be a wiring problem, a circuit board problem, a transistor insulator problem or a screw fastener problem (oversized screw head, too long, etc,)
 
My speculation is that the most likely cause is a mica power transistor insulator wafer is either missing or otherwise not working as designed for some reason and the case of the power transistor is directly connected to the power supply's frame ground.
 
Use a large USPS Flat Rate Priority Mail box to send it to me and I can find out for sure.  And pay another $15 to have me ship the repaired power supply back to you.
 
 
-Christopher Erickson
Observatory engineer
Summit Kinetics
Waikoloa, HI 96738
www.summitkinetics.com
 


From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 9:38 AM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

Jimmy,
 
Thank you for this.  I'm no electrical engineer, but I think I ran the test you suggested.
 
1) I set my meter to read DC volts.
 
2) I turned the PS ON.
 
3) I put the red meter lead on the red +13.8v DC screw terminal on the front of the PS, and the black meter lead on the chassis ground screw.  The meter read -11.72v,  not 0.
 
4) I put the red meter lead on the black -13.8v DC screw terminal on the front of the PS, and the black meter lead on the chassis ground screw.  The meter read -25.58v,  not 0.
 
So it looks as if I have a definite problem.  I don't see any obvious stray wires or strands.
 
Could this be caused by a bad cap or two?  Or am I just wasting my time with this thing?
 
Woody
 
 
 

I remember one member had warm cables back last year(?)

His DC power supply +13.8 V DC lug was touching the power supply chassis.

I think the current loop would be from
 +13.8 V DC to chassis to protective ground (green wire) to Desktop computer protective ground.
 The Desktop pc protective ground is connected to DC ground inside PC
 DC ground wire connects CP3/4 and then to the negative lug on 13.8V DC power supply completing the ground loop.
 
 With a DC voltmeter,
 I would check voltage from power supply chassis to it's negative 13.8 Volt lug at front and
 then chassis to positive lug on front of power supply.  Both should be 0 volts.
 
 The member from last year saw -13.8 volts from power supply chassis to negative lug on front of power supply.
 That means his +13.8 volt lug on front was shorted to chassis.
 
 As always, I may be! wrong again.
 
 Jimmy
 

Virus-free. www.avg.com



Re: strange electrical issue - anyone have any knowledge of what to do.

Woody Schlom <woody@...>
 

Jimmy,
 
It's a Pyramid Model: PS-15KX. 
 
You guys (particularly Roland) have shamed me into figuring out what the problem is.  So in the interest of "science" and hopefully helping others, I'll contact Christopher off-group and ship the thing to him in Hawaii and see what he can find out.
 
Woody
 

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, October 20, 2017 3:18 PM
To: ap-gto@...
Subject: RE: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.

 

Woody

I see you still have 13.8 volts between the positive and negative terminals.

Shorted cap, possibly
May be same cap your friend replaced.

Positive terminal shorted to -11 Volts below protective ground?

or

Negative terminal shorted to -25 Volts below protective ground?

I don't understand a solution to these results.

I do enjoy troubleshooting and brain teasers.

What model PS do you have and do you know of an on-line schematic.

If not, I don't think I can help any further.

Jimmy


Re: strange electrical issue - anyone have any knowledge of what to do.

Christopher Erickson
 

There probably isn't a perfect solution out there.

Only buying quality, brand name equipment helps. As would having a good multimeter in your kit and knowing how to use it.

There are 12V gfci devices out there but I have not researched what might offer simple and meaningful protection for telescopes and small observatories.

Maybe I'll look into that.


-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Oct 20, 2017 12:12 PM, "'Joseph Zeglinski' J.Zeglinski@... [ap-gto]" <ap-gto@...> wrote:


Chris,
 
    Of course, you are correct – manufacturers would rather save $2 and leave the risk to “probability and statistics”.
I was just wondering what WE can do – invest in some kind of safety device -  for our extremely expensive investment – to protect the electronics from “whatever” is causing a ground fault. That’s without pointing a/the  finger at any specific manufacturer. This problem is just all too common.
 
    Yes, a huge copper (earth ground) stake in the ground is one simple way – but perhaps inconvenient  in portable setups.
 
Joe



Re: strange electrical issue - anyone have any knowledge of what to do.

jimmyjujames
 

Woody

I see you still have 13.8 volts between the positive and negative terminals.

Shorted cap, possibly
May be same cap your friend replaced.

Positive terminal shorted to -11 Volts below protective ground?

or

Negative terminal shorted to -25 Volts below protective ground?

I don't understand a solution to these results.

I do enjoy troubleshooting and brain teasers.

What model PS do you have and do you know of an on-line schematic.

If not, I don't think I can help any further.

Jimmy


Re: strange electrical issue - anyone have any knowledge of what to do.

Joe Zeglinski
 

Chris,
 
    Of course, you are correct – manufacturers would rather save $2 and leave the risk to “probability and statistics”.
I was just wondering what WE can do – invest in some kind of safety device -  for our extremely expensive investment – to protect the electronics from “whatever” is causing a ground fault. That’s without pointing a/the  finger at any specific manufacturer. This problem is just all too common.
 
    Yes, a huge copper (earth ground) stake in the ground is one simple way – but perhaps inconvenient  in portable setups.
 
Joe