Re: [time-nuts] Symmetricom S200 PSU

2017-10-02 Thread Bryan _ 
Can second that, had a Tek 2465B scope with a faulty power supply. Only with 
the help of others more experienced in these repairs it was found to be a 
faulty opto-isolater that had degraded over time.


-=Bryan=-



From: time-nuts  on behalf of Glenn Little WB4UIV 

Sent: October 1, 2017 11:23 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Symmetricom S200 PSU

Opto-isolators degrade with time.
The "optically clear" material between the emitter and detector will
start turning opaque with time.
At least this is what my boss told me years ago.
We has a product that used opto-isolators to isolate our circuits from
phone lines.
After a few years of use, the boards started failing.
When we measured the transfer characteristics of the opto-isolators, we
found them to be degraded.
Replaced the opto-isolators and the boards functioned again.
Could have been a design error on our boards, who knows.

Opto-isolators ate cheap.

Replace it and see what happens.

Any and all parts are suspect, some more than others.
To me, it would be physically damaged parts, electrolytic capacitors,
opto-isolators, solid state devices then other parts.

73
Glenn



On 10/1/2017 12:26 PM, Lists via time-nuts wrote:
> Thanks for the reply Clint. I spent some time on it today with no luck, I do 
> have some more info though…
>
> The primary seems ok, there is a steady 329volts DC across the big cap after 
> the rectifier diodes.
>
> When you power it up under its normal load you can hear the transformer 
> whistle, which you could not hear when it was working, also measuring the DC 
> outputs gives almost exactly half the expected output, i.e.
>
> +2.54v
> +6.02v
> -5.88v
>
> Unfortunately I only have a multimeter and no ‘scope so any further fault 
> finding is difficult. I guess the next step is to replace the mos fet that 
> drives the transformer, or I guess it could be the feedback loop, which looks 
> like an opto-isolator, doubt that the isolator itself would die, but there’s 
> a PNP transistor driving it…
>
> If anyone has any other ideas I’m listening !
>
> Thanks,
> Chris
>
>
>> On 18 Sep 2017, at 20:21, Clint Jay  wrote:
>>
>> Hi Chris, if it's not blowing fuses and you're sure you've got all the 
>> capacitors ( low value ones in the primary specifically) then check all the 
>> high value resistors on the primary and continuity from reservoir capacitor 
>> to switching transistor.
>>
>> The average SMPSU usually doesn't deviate wildly from the application notes 
>> of the switching controller so if there's no specific schematic that might 
>> be a lifeline.
>>
>>
>>
>> On 18 Sep 2017 20:08, "Lists via time-nuts" > <mailto:time-nuts@febo.com>> wrote:
>> Hello Fellow Time Nuts,
>>
>> Does anyone know where I can get either a circuit diagram or a replacement 
>> PSU for a symmetricon S200 NTP server?
>>
>> I’ve fixed the original one twice before by replacing all the electrolytic 
>> caps, this time it’s popped something more critical and refuses to come back 
>> to life.
>>
>> So I either need a new PSU or a circuit diagram so I can fault find on the 
>> original.
>>
>> I’m in the UK.
>>
>> Thanks,
>> Chris
>>
>>
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>

--
---
Glenn Little ETCS(SS) USN Ret, ARRL Technical Specialist,  SBE ARRL TAPR
Amateur Callsign:  WB4UIVwb4...@arrl.netAMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI, FRA, NRA LM  QCWA  LM 28417
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
---
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Re: [time-nuts] Symmetricom S200 PSU

2017-10-01 Thread Scott McGrath 
Check to see if PSU is a symmetricom power supply it MAY be a standard merchant 
power supply for which replacements are available from 
newark/digi-key/arrow/ebay etc

Content by Scott
Typos by Siri

On Sep 18, 2017, at 3:21 PM, Clint Jay  wrote:

Hi Chris, if it's not blowing fuses and you're sure you've got all the
capacitors ( low value ones in the primary specifically) then check all the
high value resistors on the primary and continuity from reservoir capacitor
to switching transistor.

The average SMPSU usually doesn't deviate wildly from the application notes
of the switching controller so if there's no specific schematic that might
be a lifeline.



On 18 Sep 2017 20:08, "Lists via time-nuts"  wrote:

Hello Fellow Time Nuts,

Does anyone know where I can get either a circuit diagram or a replacement
PSU for a symmetricon S200 NTP server?

I’ve fixed the original one twice before by replacing all the electrolytic
caps, this time it’s popped something more critical and refuses to come
back to life.

So I either need a new PSU or a circuit diagram so I can fault find on the
original.

I’m in the UK.

Thanks,
Chris


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Re: [time-nuts] Symmetricom S200 PSU

2017-10-01 Thread Glenn Little WB4UIV 

Opto-isolators degrade with time.
The "optically clear" material between the emitter and detector will 
start turning opaque with time.

At least this is what my boss told me years ago.
We has a product that used opto-isolators to isolate our circuits from 
phone lines.

After a few years of use, the boards started failing.
When we measured the transfer characteristics of the opto-isolators, we 
found them to be degraded.

Replaced the opto-isolators and the boards functioned again.
Could have been a design error on our boards, who knows.

Opto-isolators ate cheap.

Replace it and see what happens.

Any and all parts are suspect, some more than others.
To me, it would be physically damaged parts, electrolytic capacitors, 
opto-isolators, solid state devices then other parts.


73
Glenn



On 10/1/2017 12:26 PM, Lists via time-nuts wrote:

Thanks for the reply Clint. I spent some time on it today with no luck, I do 
have some more info though…

The primary seems ok, there is a steady 329volts DC across the big cap after 
the rectifier diodes.

When you power it up under its normal load you can hear the transformer 
whistle, which you could not hear when it was working, also measuring the DC 
outputs gives almost exactly half the expected output, i.e.

+2.54v
+6.02v
-5.88v

Unfortunately I only have a multimeter and no ‘scope so any further fault 
finding is difficult. I guess the next step is to replace the mos fet that 
drives the transformer, or I guess it could be the feedback loop, which looks 
like an opto-isolator, doubt that the isolator itself would die, but there’s a 
PNP transistor driving it…

If anyone has any other ideas I’m listening !

Thanks,
Chris



On 18 Sep 2017, at 20:21, Clint Jay  wrote:

Hi Chris, if it's not blowing fuses and you're sure you've got all the 
capacitors ( low value ones in the primary specifically) then check all the 
high value resistors on the primary and continuity from reservoir capacitor to 
switching transistor.

The average SMPSU usually doesn't deviate wildly from the application notes of 
the switching controller so if there's no specific schematic that might be a 
lifeline.



On 18 Sep 2017 20:08, "Lists via time-nuts" mailto:time-nuts@febo.com>> wrote:
Hello Fellow Time Nuts,

Does anyone know where I can get either a circuit diagram or a replacement PSU 
for a symmetricon S200 NTP server?

I’ve fixed the original one twice before by replacing all the electrolytic 
caps, this time it’s popped something more critical and refuses to come back to 
life.

So I either need a new PSU or a circuit diagram so I can fault find on the 
original.

I’m in the UK.

Thanks,
Chris


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--
---
Glenn Little ETCS(SS) USN Ret, ARRL Technical Specialist,  SBE ARRL TAPR
Amateur Callsign:  WB4UIVwb4...@arrl.netAMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI, FRA, NRA LM  QCWA  LM 28417
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
---
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Re: [time-nuts] Symmetricom S200 PSU

2017-10-01 Thread Lists via time-nuts 
Thanks for the reply Clint. I spent some time on it today with no luck, I do 
have some more info though…

The primary seems ok, there is a steady 329volts DC across the big cap after 
the rectifier diodes.

When you power it up under its normal load you can hear the transformer 
whistle, which you could not hear when it was working, also measuring the DC 
outputs gives almost exactly half the expected output, i.e.

+2.54v
+6.02v
-5.88v

Unfortunately I only have a multimeter and no ‘scope so any further fault 
finding is difficult. I guess the next step is to replace the mos fet that 
drives the transformer, or I guess it could be the feedback loop, which looks 
like an opto-isolator, doubt that the isolator itself would die, but there’s a 
PNP transistor driving it…

If anyone has any other ideas I’m listening !

Thanks,
Chris


> On 18 Sep 2017, at 20:21, Clint Jay  wrote:
> 
> Hi Chris, if it's not blowing fuses and you're sure you've got all the 
> capacitors ( low value ones in the primary specifically) then check all the 
> high value resistors on the primary and continuity from reservoir capacitor 
> to switching transistor. 
> 
> The average SMPSU usually doesn't deviate wildly from the application notes 
> of the switching controller so if there's no specific schematic that might be 
> a lifeline.
> 
> 
> 
> On 18 Sep 2017 20:08, "Lists via time-nuts"  > wrote:
> Hello Fellow Time Nuts,
> 
> Does anyone know where I can get either a circuit diagram or a replacement 
> PSU for a symmetricon S200 NTP server?
> 
> I’ve fixed the original one twice before by replacing all the electrolytic 
> caps, this time it’s popped something more critical and refuses to come back 
> to life.
> 
> So I either need a new PSU or a circuit diagram so I can fault find on the 
> original.
> 
> I’m in the UK.
> 
> Thanks,
> Chris
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com 
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts 
> 
> and follow the instructions there.
> 

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Re: [time-nuts] Symmetricom S200 PSU

2017-09-18 Thread Clint Jay 
Hi Chris, if it's not blowing fuses and you're sure you've got all the
capacitors ( low value ones in the primary specifically) then check all the
high value resistors on the primary and continuity from reservoir capacitor
to switching transistor.

The average SMPSU usually doesn't deviate wildly from the application notes
of the switching controller so if there's no specific schematic that might
be a lifeline.



On 18 Sep 2017 20:08, "Lists via time-nuts"  wrote:

Hello Fellow Time Nuts,

Does anyone know where I can get either a circuit diagram or a replacement
PSU for a symmetricon S200 NTP server?

I’ve fixed the original one twice before by replacing all the electrolytic
caps, this time it’s popped something more critical and refuses to come
back to life.

So I either need a new PSU or a circuit diagram so I can fault find on the
original.

I’m in the UK.

Thanks,
Chris


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[time-nuts] Symmetricom S200 PSU

2017-09-18 Thread Lists via time-nuts 
Hello Fellow Time Nuts,

Does anyone know where I can get either a circuit diagram or a replacement PSU 
for a symmetricon S200 NTP server?

I’ve fixed the original one twice before by replacing all the electrolytic 
caps, this time it’s popped something more critical and refuses to come back to 
life.

So I either need a new PSU or a circuit diagram so I can fault find on the 
original.

I’m in the UK.

Thanks,
Chris


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