Author Topic: Tektronix DMM4050/Fluke 8846A Guard Crossing Restarted Error +370  (Read 1437 times)

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Online Johnny10

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Tektronix DMM4050 Guard Crossing Restarted Error +370


Anyone familiar with this error?

I can't measure anything from front or rear posts.
Manual lists error with no further information.
« Last Edit: October 04, 2018, 05:15:40 am by Johnny10 »
Tek TDS7104, DMM4050, HP 3561A, Tek 2465A, HP8903B, DSA602A, Tek 7854, 7834, HP3457A, Tek 575, 576, 577 Curve Tracers, Datron 4000, Datron 4000A, Fluke 181 Nanovoltmeter, Dos4Ever uTracer, HP5335A, EIP534B 20GHz Frequency Counter, TrueTime Rubidium, Sencore LC102, Tek TG506, TG501, SG503, 1062LS101
 

Offline TiN

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Re: Tektronix DMM4050 Guard Crossing Restarted Error +370
« Reply #1 on: October 04, 2018, 03:20:02 am »
I saw this one on my dead 8846A, when ethernet cable was plugged in (when meter worked a little).
But no idea what's the root cause.
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Offline commongrounder

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Re: Tektronix DMM4050/Fluke 8846A Guard Crossing Restarted Error +370
« Reply #2 on: October 04, 2018, 06:27:30 am »
I have this same meter in my shop.  I haven’t experienced this error, but it seems to imply a communication problem between the in-guard and out-guard sections of the main board.  Does the meter always hang at this point?  Might check and see if anything is blocking the optical coupling across the guard gap.
I do hope you can solve the problem.  It’s a great meter!  :)
 

Online Johnny10

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Re: Tektronix DMM4050/Fluke 8846A Guard Crossing Restarted Error +370
« Reply #3 on: October 05, 2018, 08:49:38 am »
OK So I am doing a repair on this DMM wondering if anyone has theirs open?

I have a blown diode? CR16 next to the LF353 opamp.

Checking power rails, seems something is dragging down my 15V and -15V rails. This could be part of problem.

Would like to know value.
Thanks
« Last Edit: October 05, 2018, 09:11:45 am by Johnny10 »
Tek TDS7104, DMM4050, HP 3561A, Tek 2465A, HP8903B, DSA602A, Tek 7854, 7834, HP3457A, Tek 575, 576, 577 Curve Tracers, Datron 4000, Datron 4000A, Fluke 181 Nanovoltmeter, Dos4Ever uTracer, HP5335A, EIP534B 20GHz Frequency Counter, TrueTime Rubidium, Sencore LC102, Tek TG506, TG501, SG503, 1062LS101
 

Online Johnny10

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Re: Tektronix DMM4050/Fluke 8846A Guard Crossing Restarted Error +370
« Reply #4 on: October 05, 2018, 09:21:51 am »
better pic
Tek TDS7104, DMM4050, HP 3561A, Tek 2465A, HP8903B, DSA602A, Tek 7854, 7834, HP3457A, Tek 575, 576, 577 Curve Tracers, Datron 4000, Datron 4000A, Fluke 181 Nanovoltmeter, Dos4Ever uTracer, HP5335A, EIP534B 20GHz Frequency Counter, TrueTime Rubidium, Sencore LC102, Tek TG506, TG501, SG503, 1062LS101
 

Offline picburner

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Re: Tektronix DMM4050/Fluke 8846A Guard Crossing Restarted Error +370
« Reply #5 on: October 05, 2018, 12:57:04 pm »
I read "A7", a BAV99?

 
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Offline malaino

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Re: Tektronix DMM4050/Fluke 8846A Guard Crossing Restarted Error +370
« Reply #6 on: November 15, 2018, 07:33:52 pm »

Hi, I have the same problem. When I try to measure high values ​​of resistance I get the same error.

Have you replaced the A7 diode?
Does it work?
 

Online Johnny10

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Re: Tektronix DMM4050/Fluke 8846A Guard Crossing Restarted Error +370
« Reply #7 on: November 15, 2018, 11:27:35 pm »
Changing the A7 diode made no difference to Guard Crossing error.

Are you saying you get "Guard CrossingRestarted" error only when you try and measure high resistance or whenever DMM is powered on?
Tek TDS7104, DMM4050, HP 3561A, Tek 2465A, HP8903B, DSA602A, Tek 7854, 7834, HP3457A, Tek 575, 576, 577 Curve Tracers, Datron 4000, Datron 4000A, Fluke 181 Nanovoltmeter, Dos4Ever uTracer, HP5335A, EIP534B 20GHz Frequency Counter, TrueTime Rubidium, Sencore LC102, Tek TG506, TG501, SG503, 1062LS101
 

Offline malaino

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Re: Tektronix DMM4050/Fluke 8846A Guard Crossing Restarted Error +370
« Reply #8 on: November 21, 2018, 06:15:38 pm »

Exactly, only the error appears when I try to measure high resistances. :bullshit:
 

Online Kleinstein

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Re: Tektronix DMM4050/Fluke 8846A Guard Crossing Restarted Error +370
« Reply #9 on: November 22, 2018, 04:21:57 am »
Getting the error only when measuring high resistance is odd, as there is not that much different in high resistance mode compared to normal readings. If at all the current consumption in the input referenced part would be higher in low resistance more, but not that much.
Normally the Ohms part should be very well separated from the data transmissions to keep the accuracy of the Ohms ranges. The only difference in the high ohms mode could be a relatively high voltage at some points. If there is a design fault or a defect there could be rare cases where this higher voltage could cause a latchup and this way higher than normal supply current (dragging down the supply), that could effect the rest of the operation. With a weak supply a latch-up may not blow the parts involved.

Is the error coming when using the high resistance range or is it only coming when the resistor also is high (or open circuit) ?

 

Offline malaino

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Re: Tektronix DMM4050/Fluke 8846A Guard Crossing Restarted Error +370
« Reply #10 on: November 30, 2018, 08:37:01 pm »
Yes it is, Only when I measure low or normal resistance values ​​is when I avoid the error.
 

Offline Urs42

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Re: Tektronix DMM4050/Fluke 8846A Guard Crossing Restarted Error +370
« Reply #11 on: January 30, 2019, 11:05:10 pm »
I got a Fluke 8845A with the same error. Im my case the error dosn't cause any troubles, the multimeter does work perfectly. I get this error sometimes  when i start the multimeter with the hardware power switch on the back. I can trigger the error by blocking the light from the IR LED DS2 in the second picture.

Will test some capacitors on the PCB.
« Last Edit: January 30, 2019, 11:10:50 pm by Urs42 »
 

Online Johnny10

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Re: Tektronix DMM4050/Fluke 8846A Guard Crossing Restarted Error +370
« Reply #12 on: January 31, 2019, 01:30:35 am »
I haven't gotten any further on my units since the holidays last year.

Once I found my units were not identifying Inguard software or hardware... I shelved them and started working on other projects.
Tek TDS7104, DMM4050, HP 3561A, Tek 2465A, HP8903B, DSA602A, Tek 7854, 7834, HP3457A, Tek 575, 576, 577 Curve Tracers, Datron 4000, Datron 4000A, Fluke 181 Nanovoltmeter, Dos4Ever uTracer, HP5335A, EIP534B 20GHz Frequency Counter, TrueTime Rubidium, Sencore LC102, Tek TG506, TG501, SG503, 1062LS101
 


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