Author Topic: Tektronix DPO7104 repairs  (Read 2958 times)

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Offline pasta2018Topic starter

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Tektronix DPO7104 repairs
« on: December 07, 2024, 09:41:19 am »
 When the oscilloscope is turned on, there is a fan that does not turn. It has been confirmed that there is no problem with the fan. Checking the acquisition board, the measurement found that the input terminal of the U1750 (LT1963) was shorted to ground, and the measurement found that the two ends of the C1750 were also short-circuited. May I ask who has DPO7104, please measure whether these two ends of the normal instrument are short-circuited.
 

Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #1 on: December 07, 2024, 09:47:33 am »
I removed the acquisition board and tested it again, and found that there was no short circuit. It seems that the short circuit before the test may be caused by the power interface board.
 

Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #2 on: December 07, 2024, 10:07:51 am »
It's really interesting, and then disconnect the power interface board from the mother board, then I find that the mother board 3.3V is short-circuited with GND
 

Offline squadchannel

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Re: Tektronix DPO7104 repairs
« Reply #3 on: December 07, 2024, 10:14:38 am »
Check again with the acq board alone and nothing connected.
 

Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #4 on: December 07, 2024, 10:55:24 am »
Thanks,now I can confirm it's the mother board failure. 3.3V out is shorted to GND.
 
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Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #5 on: December 07, 2024, 01:31:46 pm »
it's the power supply CVR460-96p01b01,3.3V out is shorted.
 

Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #6 on: December 12, 2024, 08:29:25 am »
Still not fixed. At present, the measured power supply voltage is normal, when I remove the acquisition board, both fans on the side of the oscilloscope rotate, but after the acquisition board is installed, only one fan rotates. Looking at the maintenance manual, it says that the acquaintion board will detect the temperature and then adjust the speed of the fan, who knows where the circuit for detecting and adjusting the fan is?
I saw that there is a place marked with sense on the acquisition board, it seems to be C100, and the two ends of the measurement are in a short-circuit state, I wonder if this is normal?
« Last Edit: December 12, 2024, 08:32:43 am by pasta2018 »
 

Offline iAleks

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Re: Tektronix DPO7104 repairs
« Reply #7 on: December 12, 2024, 09:39:09 pm »
I saw that there is a place marked with sense on the acquisition board, it seems to be C100, and the two ends of the measurement are in a short-circuit state, I wonder if this is normal?
I check resistance on work board this capacitor one side 0 Ohm to GND other side 8 Ohm to GND.

Update:
Little bit reverse engineering, FAN's connect to transistors Q632 and Q631 on main board (R632,R641,R631,R642=475 Ohm), next PWM signals go to acquisition board, on acquisition board PWM signals connect to U1305 its ADT7476 (bottom side), PWM1 connect to pin24 U1305, PWM2 connect to pin10 U1305.
I highly recommend when you do some tests, connect GOOD fan's for cool acquisition board (when i repair my scope i cool this board with 3 FAN's, two for ADC's one for NI BGA chip) and PSU-Motherboard. And be very careful with acquisition board try hard not bend this board (when you disconnect this), don't apply any force or litle hit to BGA heatsinks ADC, Preamp, DEMUX.
« Last Edit: December 12, 2024, 11:50:11 pm by iAleks »
 
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Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #8 on: December 13, 2024, 07:38:04 am »
Really appropriate for your information, that's really useful. I will check the signals and be careful with acquisition board.
 

Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #9 on: December 14, 2024, 12:25:04 pm »
I checked my scope, the power interface board is the same with yours. The acquisition board is different, pwm1 and pwm2 is shown in the picture,it is connect to pin 10 and pin24 of adt7476
 

Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #10 on: December 14, 2024, 01:15:34 pm »
I guess the Q631 or Q632 is fault.The two pin resistance of each one is not the same,while Q631 is about 2k,and Q632 is infinity.
It,s marked with 2A X,it's MMBT3906,a PNP transistor.
« Last Edit: December 14, 2024, 01:18:10 pm by pasta2018 »
 

Offline coromonadalix

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Re: Tektronix DPO7104 repairs
« Reply #11 on: December 14, 2024, 02:17:41 pm »
i would say  clean your pcb

it is crusty  and that could cause problems if it continues and humidity goes in that
 

Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #12 on: December 14, 2024, 04:22:44 pm »
I don't know what to clean well. I tried cleaning with water or alcohol and it didn't seem to work. It looks very clean when it gets wet, and it looks like this when it's dry.
 

Offline iAleks

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Re: Tektronix DPO7104 repairs
« Reply #13 on: December 14, 2024, 09:45:58 pm »
I guess the Q631 or Q632 is fault.The two pin resistance of each one is not the same,while Q631 is about 2k,and Q632 is infinity.
It,s marked with 2A X,it's MMBT3906,a PNP transistor.
No, this is some N channel mosfet. Fan current 0,52A. You need some mosfet with similar parameter Vthreshold
 

Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #14 on: December 14, 2024, 10:17:48 pm »
Oh my god, thanks! Can you tell what is marked on Q631 of your scope? Mine is 2A XK8
 

Offline iAleks

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Re: Tektronix DPO7104 repairs
« Reply #15 on: December 14, 2024, 10:22:53 pm »
Oh my god, thanks! Can you tell what is marked on Q631 of your scope? Mine is 2A XK8
2ax3A
 

Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #16 on: December 15, 2024, 01:01:32 am »
Thanks again.It may be SI2302ADS-T1-E3.
By the way, I saw you upgrade the 7104 to 7354 and generate an option key, have you successed?
 

Offline iAleks

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Re: Tektronix DPO7104 repairs
« Reply #17 on: December 15, 2024, 01:21:00 am »
Thanks again.It may be SI2302ADS-T1-E3.
By the way, I saw you upgrade the 7104 to 7354 and generate an option key, have you successed?
Yes i think this mosfet fine for this.
Upgrade DPO7104-DPO7354 possibly  only if scope have acqusition board with 4 ADC, 8DEMUX and track and hold ic, and in this moment SPC fail, i search someone who have DPO7254-DPO7354 for copy some files from it.
Your acquisition board have 2ADC 4DEMUX you can activate only some options and max memory, on this forum have links to keygen, or you can send me your sn and i generate key for you.
 

Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #18 on: December 15, 2024, 01:59:34 am »
I get some information from the service manual,hope it's useful.
Can you post the keygen link here,I can not find it.
« Last Edit: December 15, 2024, 02:02:36 am by pasta2018 »
 

Offline calibrationfixture

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Re: Tektronix DPO7104 repairs
« Reply #19 on: December 15, 2024, 05:14:26 am »
Hi pasta2018,

You need the Program(s):
- gen.py and
- validate.py

The last is used to split out the Option Mask for existing Keys.

Both can be found at:

https://0xacab.org/mitic/tek-ssc/tree/master

And a list of possible Options (page 2-9) for your DPO7104 attached.

Success,

Calibrationfixture

« Last Edit: December 15, 2024, 05:32:36 am by calibrationfixture »
 
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Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #20 on: December 15, 2024, 07:14:24 am »
Thanks. I will learn it, hope I can fix my dpo7104 first
 

Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #21 on: December 19, 2024, 09:56:39 am »
It turned out that R632 was desoldered
 

Offline iAleks

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Re: Tektronix DPO7104 repairs
« Reply #22 on: December 19, 2024, 01:56:31 pm »
Your scope work now? SPC pass?
 

Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #23 on: December 19, 2024, 02:16:04 pm »
Not yet.Now the two fans are running normally.
I uninstalled the tekscope before and am now reinstalling it, not sure if the acquisition board is still faulty.
 

Offline pasta2018Topic starter

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Re: Tektronix DPO7104 repairs
« Reply #24 on: December 20, 2024, 05:37:36 am »
Quite difficult.
When I install tekscope, it reports ddsigninstall32.exe error and then continue.

After installation, the tekscope start and then it report x08e error, then shutdown and restart.


 


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