Author Topic: HP 6671A option J05 J09 5V 250A Power Supply  (Read 6648 times)

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Offline Jay_Diddy_B

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HP 6671A option J05 J09 5V 250A Power Supply
« on: July 20, 2015, 02:53:16 pm »
Hi,

I am going to share a few photographs of the inside of a HP 6671A 2000W power supply.

The standard version is 8V 220A. The one I have is marked Option J05 and J09. I am not exactly sure what the options are, but there was a sticker on the front panel indicating 5V 250A.

The unit was known to be bad when I bought it. It took it apart to see if I could find what is wrong.

Photographs

This first picture is an overview. The power enters the unit at the bottom left and exits at the top left. The MOSFET assembly and rectifier assembly are in the middle.



This second picture shows the transformer, choke and rectifier diodes. The diodes are mounted on the heatsink. The connections are made with bolts:



The third picture shows the output capacitors:




Damage

There has been some capacitor leakage and subsequent damage. C305 has leaked and damaged the AC Input board in the area shown:



Here is the placement diagram from the service manual:



And the schematic:



The parts that are damaged are fairly common parts, so there should be no difficulty finding replacements.

It is going to be quite difficult to get the AC Board out of the unit to perform the repair.

Regards,

Jay_Diddy_B


« Last Edit: July 20, 2015, 02:55:11 pm by Jay_Diddy_B »
 

Offline Jay_Diddy_B

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #1 on: July 21, 2015, 03:54:03 am »
Hi group,

Here is a continuation of the repair.

I removed the AC Board following the instructions in the manual. It is quite a task. This pile of screws of gives you an idea:



I removed the electrolytic capacitors in the bias supply area:



Here is a close up of the damage:




And the capacitors that I pulled out. The capacitors were made by Sprague in 1991:



I then cleaned the board with a stiff brush and some IPA. I will be replacing more parts and I will clean the board some more:



It doesn't look like there any damaged tracks. HP used a process where the tracks are plated with gold, even under the solder mask.

I have ordered some replacement parts.

Regards,

Jay_Diddy_B



« Last Edit: July 21, 2015, 03:55:52 am by Jay_Diddy_B »
 

Online BravoV

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #2 on: July 21, 2015, 04:24:10 am »
 :popcorn:

Always love to watch & follow your repair/restoration threads on various T&M gadgets, especially from experienced EE.

Keep them coming.  :-+

Offline edpalmer42

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #3 on: July 21, 2015, 05:09:13 am »
In the last picture, there's a resistor between U302 and U309.  What is peeking out from underneath the resistor?  It looks like a wire clipping or a trace that's going nowhere.

Ed
 

Offline Jay_Diddy_B

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #4 on: July 21, 2015, 12:25:43 pm »
Hi Ed and the group,

In the last picture, there's a resistor between U302 and U309.  What is peeking out from underneath the resistor?  It looks like a wire clipping or a trace that's going nowhere.

Ed


There is a trace on the board. Actually there are two traces, on each side of the board. They are shown on the schematic:



These are guard traces. If there is contamination or moisture on the board that would cause small currents to flow across the isolation you want these currents to flow to the emitter of the optocoupler. If the small currents reach the base they are amplified by the gain of the Darlington transistors.

I have ordered a new optocoupler. I will scrub the board under the optocoupler.

[ I know all about this. I had this problem one of the products I designed. I had leakage caused by no-clean flux residue. I had to cut the base leads off the optocouplers, until I could switch to parts without a base lead.]


Regards,

Jay_Diddy_B
 

Offline Jay_Diddy_B

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #5 on: July 23, 2015, 02:21:50 am »
Hi,

I did a little more work on the repair this evening.

First I removed more of the parts and cleaned the board with a stiff brush and IPA:



I then installed new components:




It looks a lot better. I have to put the power supply back together.

Regards,

Jay_Diddy_B

 

Offline Jay_Diddy_B

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #6 on: July 25, 2015, 02:21:02 pm »
Hi group,

When I was putting the unit back together, I found another problem. R400 one of the soft-start resistors was broken, and measured open circuit. This is a picture of the resistor removed from the board:




The purpose of the resistor is to limit the inrush current when the unit is turned on. After about 10 seconds the resistor is shorted by a relay. Here is the schematic:



With a little effort I was able to find a replacement resistor. These 25W wire wound resistors are not stocked at Digikey etc.
I did find one New Old Stock at a local store:



This is a picture of the resistor installed in the bracket, mounted on the board:



Sense Leads

These high power units use remote sense. This allows the voltage to be regulated at the load, as oppose to being regulated at the power supply. If you are not using remote sense, you must connect the sense leads at the output of the power supply. The Sense terminals are normally marked +S and -S on HP / Agilent / Keysight power supplies:




Testing

I used a 120 to 240 Auto transformer to power the unit. A quick check shows the unit is now working:



Another successful repair.

Regards,

Jay_Diddy_B


« Last Edit: July 25, 2015, 02:24:13 pm by Jay_Diddy_B »
 

Offline saposoft

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #7 on: December 10, 2015, 04:26:19 pm »
Hi
I too got one of these beasts, but it was intended to be an 8 Volt one, turned out that I have the options that you have and it's only 5V.
Do you know of a sure way to convert it back to 8 Volt operation ?
I've already tried to recalibrate it'e OVP for ops over 6,4 V but no luck , it doesn't go over 6,4V.

Alessandro
 

Offline Jay_Diddy_B

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #8 on: December 10, 2015, 04:44:12 pm »
Hi
I too got one of these beasts, but it was intended to be an 8 Volt one, turned out that I have the options that you have and it's only 5V.
Do you know of a sure way to convert it back to 8 Volt operation ?
I've already tried to recalibrate it'e OVP for ops over 6,4 V but no luck , it doesn't go over 6,4V.

Alessandro


Alessandro and the group,

I have both versions of the power supply. The service manual doesn't describe the options.

The good news is that the main transformer 9100-4909 is the same in both units.

I suspect that the option is implement in the EEPROM. There are some clues on page 64 of the service manual, figure 3-18.



Regards,

Jay_Diddy_B

 

Offline saposoft

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #9 on: December 10, 2015, 05:07:05 pm »
thanks a lot Jay
Will investigate further on the issue and report to the group.
 

Offline saposoft

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #10 on: March 09, 2016, 10:53:55 pm »
Just a quick follow up to my previous message.
I'm in the process of finalizing a program to restore the eeprom settings to verify the theory of Jay.
Will post news when the program will be finished.
So little time so many toys ...
 

Offline saposoft

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #11 on: March 14, 2016, 01:53:41 pm »
Well Software for EEprom initialization Ready .
Started , written new (original) calibration constant , performed Voltage calibration , NO JOY  >:(
Looks like the OPTION J05 (5Volt output Max) has something more than few constant in the EEProm.
Perfoming calibration 1st step is : the pwr supply output 1/10 of max out voltage and sure as hell it output 0.4461 V, roughly 1/10 of 5V...
Grrrrrr back to the bench
Any Indication Jay ? is your service man for sernum 36xxxxxxxxx and above ? mine is and my pwr supply is 3129-xxxxx.
I have available an Original HP Operating Guide manual for my serial number if anyone needs it just ask I can scan it and post to K4 site
Software availabe for asking , needs Prologix usb inteface.
Alex
 

Offline Shef

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #12 on: August 22, 2020, 02:05:09 am »
Добрый всем день!

Хочу тоже немного поделиться опытом - аналогично проблеме выше, возникла пробоем  и у меня !
Конденсаторы 50 В 1000 мкфполностью протекли! из-за этого возникла большая коррозия печатной платы, аппарат начал "глючить". После замены конденсаторов и полной пропайки платы все стало нормально.

Залужены полностью коррозионные дорожки!
Заменены электролитические конденсаторы
Покрыта заново лаком печатная плата.
« Last Edit: August 22, 2020, 02:09:18 am by Shef »
 

Offline Shef

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #13 on: August 22, 2020, 02:09:54 am »
Фото
 

Offline Jay_Diddy_B

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #14 on: August 22, 2020, 02:11:08 am »
Hi,

This message reads, thanks to google translate:

Good day everyone!

I also want to share a little experience - similar to the problem above, I also had a breakdown!
50V 1000uF capacitors are completely leaking! Because of this, there was a lot of corrosion on the printed circuit board, the device began to "glitch". After replacing the capacitors and completely soldering the board, everything became normal.

Completely tinned corrosive tracks!
Replaced electrolytic capacitors
Re-varnished printed circuit board.


So, the same issue.

Jay_Diddy_B
 

Offline Shef

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #15 on: August 22, 2020, 02:12:37 am »
Thank you so much!
 

Offline Jay_Diddy_B

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #16 on: September 27, 2020, 05:19:37 pm »
Hi group,

Today I made a 3D printed safety cover for an HP6671A. The original part number is 5040-1676.

I was able to take the measurements from an original cover. The metal parts I purchased. It was a Hubbell 3/4" 2 Screw Saddle Connector (Part Number NMC075R1 from Canadian Tire).

Original
[attachimg=1]


This is a picture of the original cover.

3D Printed Version

Here is the 3D printed version before the raft and the supports have been removed:

[attachimg=2]


And here is the finished assembly:

[attachimg=3]


I have attached a zipfile containing the STL file.

Regards,
Jay_Diddy_B
[attachurl=4]
« Last Edit: September 27, 2020, 05:22:56 pm by Jay_Diddy_B »
 

Offline Jay_Diddy_B

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #17 on: September 30, 2020, 03:24:28 am »
Hi,

I am going to share a document that I prepared for changing the capacitors on the AC Board assembly (A4). This should apply to other members of the power supply family:

  • 6571A
  • 6572A
  • 6573A
  • 6574A
  • 6671A
  • 6672A
  • 6673A
  • 6674A

I chose Kemet PHE850 series capacitors to replace the Rifa X and Y capacitors.

Jay_Diddy_B

[attachurl=1]
 

Offline Jay_Diddy_B

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #18 on: September 30, 2020, 03:40:09 am »
Hi,
I am going to share the design of a 3D printed version of the 5040-1674 Cover-Output-Buss. This is a safety cover that goes over the output bus bars.

The following units use this cover:

6571A
6572A
6573A
6574A
6575A
6671A
6672A
6673A
6674A
6675A
85301A-E95
E4356A
E4370A
E6189A
E6238A



Original Part

[attachimg=1]

[attachimg=2]


Replacement Design

A replacement was designed in Fusion 360:

[attachimg=3]


Printed part

[attachimg=4]


I have attached the STL file

This took 8 hours to print.

Regards,
Jay_Diddy_B

[attachurl=5]
« Last Edit: September 30, 2020, 03:42:42 am by Jay_Diddy_B »
 

Offline Jay_Diddy_B

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #19 on: September 30, 2020, 03:10:45 pm »
Hi,

Here are some additional pictures of the covers installed on the back of a power supply:

[attachimg=1]



[attachimg=2]


(It hard to get a good picture of the black cover)

Regards,
Jay_Diddy_B
 

Offline Jay_Diddy_B

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Re: HP 6671A option J05 J09 5V 250A Power Supply
« Reply #20 on: October 02, 2020, 03:35:47 am »
Well Software for EEprom initialization Ready .
Started , written new (original) calibration constant , performed Voltage calibration , NO JOY  >:(
Looks like the OPTION J05 (5Volt output Max) has something more than few constant in the EEProm.
Perfoming calibration 1st step is : the pwr supply output 1/10 of max out voltage and sure as hell it output 0.4461 V, roughly 1/10 of 5V...
Grrrrrr back to the bench
Any Indication Jay ? is your service man for sernum 36xxxxxxxxx and above ? mine is and my pwr supply is 3129-xxxxx.
I have available an Original HP Operating Guide manual for my serial number if anyone needs it just ask I can scan it and post to K4 site
Software availabe for asking , needs Prologix usb inteface.
Alex


Hi group,

Saposoft asked this question a long time ago. I have investigated the differences between the standard 6671A and the J05 option.

The J05 option reduces the maximum output voltage from 8V to 5V and increases the maximum current from 220A to 250A.

I removed the A5 control board from my J05 unit. I was able to see, because of the flux residue, which resistors had been changed.

Conversion J05 to standard.

Replace three resistors on the A5 control board.
Reprogram the NM93C56 EEPROM on the A1 front panel board.

It is possible to program the EEPROM inside the unit over GPIB. I found it easier to pull the EEPROM and use my Xeltek device programmer.

I have attached files with the instructions.

I have attached the binary files of the EEPROM.

It is advisable to follow the calibration procedure in the manual after this modification.

Regards,
Jay_Diddy_B

[attachurl=1]

[attachurl=2]



 
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