Author Topic: HP 4274A LCR Meter - mini teardown  (Read 26154 times)

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Offline velik_kazakov

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Re: HP 4274A LCR Meter - mini teardown
« Reply #175 on: January 08, 2019, 06:05:13 pm »
Santa Claus come to me too :) with working 4274A in good working condition.
My A9 board is different compared to the pictures I find in the net. Want to ask if someone have backup of the eproms for this board (part numbers 04274-85041.... 04274-85046). If not I think to try to read it w/o desoldering from the board. Think to solder a dip in the empty place and to desolder only the ROM selector. After to try to select every eeprom and to read it. What you guys think about this or need to desolder every eeprom and to read it.
« Last Edit: January 08, 2019, 07:44:49 pm by velik_kazakov »
Sorry for my bad English!
 

Offline MateKrisz

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Re: HP 4274A LCR Meter - mini teardown
« Reply #176 on: January 09, 2019, 07:19:13 am »
Hi,
Yours very nice too! I think only way if you desoldering the ROMs. After you can solder the correct sockets and push the original ROMs. My different, little earlier than yours.  Just a question. Your equipped with 001 or 002 option? Mine is equipped with 002 option, 100V BIAS card, and if I set the second position (<2F 35/100V) on the rear panel I can't measure over 200nF. I really don't know it is normal or not.
« Last Edit: January 09, 2019, 08:09:46 am by MateKrisz »
 

Offline velik_kazakov

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Re: HP 4274A LCR Meter - mini teardown
« Reply #177 on: January 09, 2019, 05:23:41 pm »
Hi,
my options - GPIB, 35Vdc bias, Battery. Will try this night about this measuring and will let you know. Get a box with fixtures too with my unit :).
Some are from other HP equipment but can be used with small mods.
BTW on the first picture is connected 1000uF electrolytic cap with dc bias 28.5 v. All looks correct.
« Last Edit: January 09, 2019, 05:29:21 pm by velik_kazakov »
Sorry for my bad English!
 
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Offline MateKrisz

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Re: HP 4274A LCR Meter - mini teardown
« Reply #178 on: January 10, 2019, 08:02:17 am »
Hi,

Thanks for your answer! Today I read in the user manual the following: "Note: Option 002 internal dc bias should be used for capacitance measurements below 0,1uF." I think because the 35Vdc bias card voltage accuracy is 0,5% and the 100Vdc bias option has 2%.
So I need to change the bias card to 35Vdc version or I need a 16047B fixture and I can use the 200V Bias option if I would like to measure higher capacity than 0,1uF with Bias.

I saw your plus fixtures. Looks good! :D Do you have an unused fixture for sale? :)

Here are 2 picture of my measuring. You can compare with yours. The HP 3456A show the current bias voltage.







Krisz
 

Offline velik_kazakov

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Re: HP 4274A LCR Meter - mini teardown
« Reply #179 on: January 10, 2019, 06:36:16 pm »
Hi,
I have no time yesterday to test the measuring of big caps with dc bias , but will do this today.
I have some 16048 fixtures, but all are with broken clips. Maybe will use one of them to do a fixture like 16047. I have no 16047 in the set. Something else - I have one good probe from HP 4328A (like on this pictures - https://www.woutersenwouters.be/sold-products/101/hewlett-packard-4328a-milliohmmeter-with-hp16005a-clip-type-probes). They use this socket RM12BRD-5S-71 HRS Hirose (https://www.ebay.co.uk/itm/Connettore-circolare-5-poli-femmina-RM12BRD-5S-71-HRS-Hirose/223317913580). It is very strong clips and one that I have are in very good condition + extra 3 spare clips. I think to order one socket and to install it on a 16048 to be used with this probe. It looks good for in circuit measuring. The clips are very fine on the ends. BTW I have one test fixture 16096A tha I can't use. I think to try to sell it and when sell it to buy one original 16047 A or B for my 4274A. If I find some time in the future will use one 16048 to do it for SMD elements.
Sorry for my bad English!
 

Offline Inverted18650

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Re: HP 4274A LCR Meter - mini teardown
« Reply #180 on: January 11, 2019, 01:09:14 pm »
NICE SCORE. The adapters are a small fortune too.

Offline velik_kazakov

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Re: HP 4274A LCR Meter - mini teardown
« Reply #181 on: January 11, 2019, 06:21:12 pm »
I do some tests with DC bias and 3300uF cap. No problem to measuring this cap. Just the setting time for the bias is longer. Here have some pics with 0v, 10v and 20v bias.
BTW, find a cracked Rifa cap inside the item, exchange it with new one. If it blow they generate lots of smell for some days in the room. I still remember this smell from last one that blow in my hands :). This Rifa element is hidden under the AC traf and need to remove the traf to reach and exchange this cap.
« Last Edit: January 11, 2019, 06:33:18 pm by velik_kazakov »
Sorry for my bad English!
 

Offline MateKrisz

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Re: HP 4274A LCR Meter - mini teardown
« Reply #182 on: January 11, 2019, 11:38:14 pm »
Hi,
Thank you for the pictures of your measurement. I really don't know what happen at me, because when I try to measure a 47uF capacitor with 5V Bias,  I see how charging very slowly and just Err4 flashing. I will try to order a 001 option +35Vdc card. If you sell I wanna to buy a 16048 with broken clips.
With the 4274A working well the BK Precision TL89F1 fixture too. It is much cheaper than original HP/Agilent 16047A. See my attached picture.

https://www.mouser.bg/ProductDetail/BK-Precision/TL89F1?qs=%2fha2pyFaduhLmatVqNnrkFl7T9kQbnjqWyUnSv4N2%2fx4a2gZHtHWyA%3d%3d or

https://www.globaltestsupply.com/product/bk-precision-tl89f1






« Last Edit: January 12, 2019, 12:28:39 am by MateKrisz »
 

Offline velik_kazakov

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Re: HP 4274A LCR Meter - mini teardown
« Reply #183 on: January 14, 2019, 11:05:20 pm »
Hi,
Thank you for the pictures of your measurement. I really don't know what happen at me, because when I try to measure a 47uF capacitor with 5V Bias,  I see how charging very slowly and just Err4 flashing. I will try to order a 001 option +35Vdc card. If you sell I wanna to buy a 16048 with broken clips.
With the 4274A working well the BK Precision TL89F1 fixture too. It is much cheaper than original HP/Agilent 16047A. See my attached picture.

Hi,
maybe will order one TL89F1 in the future. For now will use 16048 - it work perfect. If you want I can to make some pictures in the weekend of the test fixtures and if you have an interest of it to comment with me. Maybe will use one of them to use it and to make it for SMD. Have a friends that will do all parts that need to do all, but have no time now for this. Most impotent for me is to find a time to back up the eproms :).
Sorry for my bad English!
 

Offline MateKrisz

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Re: HP 4274A LCR Meter - mini teardown
« Reply #184 on: January 17, 2019, 09:51:24 am »
Hi,
Yes it is good idea! The BK has Smd fixture too, really not expensive. I asked my friend about ROM backup. He can save it and write another epproms, but need remove the eproms from the PCB. My CPU board is different, and I my rom images not compatible with yours unfortunetly.
 

Offline precaud

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Re: HP 4274A LCR Meter - mini teardown
« Reply #185 on: January 17, 2019, 03:28:47 pm »
4274A and 4275A use same ROM images. See:

https://www.eevblog.com/forum/repair/the-repair-from-he!!-hp-4275a-lcr-meter/msg1490586/#msg1490586
 
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