Author Topic: Advantest R6144, DC Voltage/Current Source, [needs repair]  (Read 5206 times)

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Offline HighVoltage

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Advantest R6144, DC Voltage/Current Source, [needs repair]
« on: June 23, 2016, 09:30:02 am »
This Advantest R6144, DC Voltage/Current Source was very cheap, because it is dead.
Luckily I have a second one, perfectly working, so I hope the repair is possible.
I looked everywhere for some schematics but no luck and may be it is not available.

Maybe someone here has a complete diagram for these Advantest sources.
All I have so far, is the operational / user manual in English:
ds.theatr.us/test-equipment/Advantest/6144_ope_e.pdf

Well, I took it apart.
There are two large PCB's in the unit and the top one is directly connected to the bottom one, so it is not possible to probe inside the system, because the top PCB has to be attached.

Anyone here have experience in repairing Advantest test gear?
Where to start?
I think will start with the Power Supply, the fuse is alright.

Here are my first pictures:

« Last Edit: June 23, 2016, 09:32:30 am by HighVoltage »
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Offline HighVoltage

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #1 on: June 23, 2016, 09:39:30 am »
Here are some pictures of the top logic board
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Offline MosherIV

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #2 on: June 23, 2016, 11:23:34 am »
Hi

Nice score if you get it working (would love one myself but too mean with my money to splash out on one).

"This Advantest R6144, DC Voltage/Current Source was very cheap, because it is dead."
Please explain what the symptoms are :

Do you mean it will not power on?

Have you done the simple checks :
fuses OK
Power cord OK
Check power switch OK
Check transformer OK
Check power rails for correct voltages
« Last Edit: June 23, 2016, 11:25:33 am by MosherIV »
 
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Offline HighVoltage

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #3 on: June 23, 2016, 01:11:18 pm »
The unit did NOT power on at all.
That problem was easy, both bridge rectifier were dead and I installed new parts.

Now it is turning on and it is working, but the values do not make any sense.
The current source is right on
But the voltage source is far off

For instance, if I set it to 10V output is 11.3V
Or set to 1.000 V, the output is 0.890V

So, I opened up the my second unit and follow along some signal path on the PCB.
I added some LEDs to the relays, to see when they are ON and OFF.

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Offline MosherIV

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #4 on: June 23, 2016, 02:16:31 pm »
"But the voltage source is far off

For instance, if I set it to 10V output is 11.3V
Or set to 1.000 V, the output is 0.890V"

Not sure tracing the signal path is much help.

The Voltage output must be set by the processor somehow, a DAC of some kind.
Have a look round the boards and check the IC part numbers for some kind of DAC.

Alternatively, the DAC should be fed by some kind of precision voltage reference.
Have a look round the boards and check the IC part numbers for some kind of voltage reference device.
 
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Offline HighVoltage

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #5 on: June 23, 2016, 02:25:28 pm »
Here is a picture of the voltage reference.
It is an LT1021

Interestingly, the 100mV Range is right on spot.

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Offline deadlylover

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #6 on: June 23, 2016, 02:34:23 pm »
There's a service manual from the same site, good luck with the repair! No schematics unfortunately but there's a decent troubleshooting section.
 

Offline HighVoltage

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #7 on: June 23, 2016, 03:06:49 pm »
There's a service manual from the same site, good luck with the repair! No schematics unfortunately but there's a decent troubleshooting section.
Wow, this is great, it even has the parts list inside.
Thanks so much.
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Offline TiN

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #8 on: June 23, 2016, 03:43:26 pm »
HV is on fire lately, good job.
Check the feedback loop for other V-ranges...
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Offline HighVoltage

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #9 on: June 23, 2016, 05:20:29 pm »
I found a faulty 74HC374 by comparison to my good unit.
The chip is ordered, will be here in a few days.
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Offline HighVoltage

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #10 on: June 23, 2016, 07:01:47 pm »
HV is on fire lately, good job.
Check the feedback loop for other V-ranges...
TiN
I would like to have your repair skills ...

It looks like I have circled in the problem with two broken chips
If confirmed, I will write it down in detail.

It is just a surprise to find two completely (as it seems) unrelated problems
Powersupply with broken bridge rectifiers and logic chips
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Offline HighVoltage

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #11 on: June 25, 2016, 11:13:29 am »
Check the feedback loop for other V-ranges...

Partial success.
OK, I installed one new FlipFlop and one Hex Inverter
All ranges work now, almost right spot on.

But ... the 1 V range is far off
Here are a few measurement examples:

Set to            Output
1.0000 V        1.243 V
1.1000 V        0.681 V
0.9000 V        0.275 V
1.2000 V        71 mV

TiN's suggestion about the feedback loop is probably right on.

But I find it very difficult to search and find any feedback loop, without the schematics.
How would you proceed?





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Offline TiN

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #12 on: June 25, 2016, 12:48:32 pm »
Follow the rabbit....erm....signal I meant. You have a reference, find the DAC (time width modulator output) which generates voltage to output PA.
Your issue is in output differential amplifier and/or protection on it's output. Check polarity switching too, if it's same problem there.
Check signals in section 6.5 Output voltage error of Maintenance manual. I'd start from there.
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Offline 3g57

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #13 on: October 08, 2017, 12:08:43 pm »
Hello guys. Hi TiN. I am glad to communicate.
Advantest R6144 check and correct if necessary.
The accuracy of the calibration of the device depends on the PWM operation. An important factor is the period.
The accuracy of the frequency of the crystal oscillator directly affects the accuracy of operation and calibration. The quartz oscillator provides a frequency for PWM!
From photos you will understand.
You can ask a question.

Advantest R6144 TP3 Frequency
https://youtu.be/y0OmU4l0i_M

Advantest R6144 TP5 Period
https://youtu.be/XpGoXbMETYE

with best wishes 3G57
 
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Offline HighVoltage

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #14 on: October 08, 2017, 12:28:51 pm »
This is great information on the R6144, thank you 3g57

I got my broken unit back to work a while back.
All that was wrong was one logic chip.
Replaced it and it worked perfectly.


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Offline 3g57

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #15 on: October 14, 2017, 11:08:09 am »
Good afternoon guys. High Voltage Hello!
Thanks for the feedback.
High Voltage! I need your help.
It takes you a little time. I'm sorry.
Advantest R6144 has one element in which I doubt.
This is the R35 SIP RESISTOR ie the resistive matrix.


I want to ask you to measure her resistance.
R35 it is necessary to unsolding (do not overheat) and measure its resistance
between the terminals:
                         PIN to PIN.
                1-2, 1-3, 1-4, 1-5, 1-6.
                       2-3, 2-4, 2-5, 2-6.
                              3-4, 3-5, 3-6.
                                     4-5, 4-6.
                                            5-6.

I am give You an example of table.  I have doubt in my first section.



Please write Your result in the table.
Later I will send you for comparison my measurements of the first section. It is important. It's a divider!
The accuracy of the calibration and the readings in the lower orders depend on it.
And yet you have on the analog board from the side of soldering on the resistor R56
Two diodes connected to each other are connected in parallel.
Question: what is their marking???
I have not installed them, and I bought a new Advantest R6144.
I will be very grateful to you!
All the best! 3G57.
 
A few screens from the last my calibration(2016):


 Photos:


If You have a questions - ask me,  please.
HV I will wait for Your reply.
Best regards.



« Last Edit: October 15, 2017, 12:34:50 pm by 3g57 »
 

Offline Justincase1979

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #16 on: December 13, 2017, 05:25:23 pm »
Quick question for HighVoltage. I just got a R6144, and it has pretty much the exact same problem as you describe, with voltages on the 1V range being all over the place. If I read your later post correctly you traced this to a faulty logic chip!? If so, which one?
 

Offline HighVoltage

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Re: Advantest R6144, DC Voltage/Current Source, [needs repair]
« Reply #17 on: December 13, 2017, 05:59:56 pm »
Quick question for HighVoltage. I just got a R6144, and it has pretty much the exact same problem as you describe, with voltages on the 1V range being all over the place. If I read your later post correctly you traced this to a faulty logic chip!? If so, which one?
Actually I had to exchange 3 logic chips until it worked again.
But I don't remember off hand which one. I will have a look after I am back from traveling.
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