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Products => Test Equipment => Topic started by: Galen on July 15, 2020, 02:14:59 am

Title: BK Precision 2540B-GEN blank screen
Post by: Galen on July 15, 2020, 02:14:59 am
All, I got a BK 2540B-GEN, startup with blank screen, cost 30 bucks. The seller said no repair for it. It's a BW 60MHz with 1GSa/s, plus a 20MHz arbitrary wave generator. As it's body appearance is good, and price is so low, I bought it. Will reach to me in 2 days.

Blank screen, so the power maybe OK, but need to check. Then possible problem could be the CPU reset circuit, or a bad crystal? Will check by this sequence when received it.

Searched the internet, can only find the user manual, no service manual.

The BW is a bit lower. There is a BK2542B-GEN with 100MHz BW and 40MHz wave generator. I guess there should be a way to do a BW upgrade for BK2540B-GEN, but didn't find any clue on the net. Very appreciate if you know something about this and can share here. Thanks in advance.
Title: Re: BK Precision 2540B-GEN blank screen
Post by: Galen on July 25, 2020, 04:05:20 pm
The scope was fixed last Thursday night. 
Initial check found the +5V is almost 0V. And the 7805 IC is very hot.  So I replaced the 7805 IC.  but +5V still 0.
So must be a short in the main board. Visual check, didn't find any abnormal. 
Measure +5V lead to GND at main board, short circuit.  So trace the +5V trace, desolder a cap 470u, found it's short.  Measure the +5V lead to GND, still short.  Then desolder another cap 470u on the +5V trace, it's short too.  Measure +5V lead to GND, no short anymore.
Replace these 2 cap. install the power board and main board back, power on the scope, it LIVE! everything is normal.  Self cal passed. Great!
Next steps could be:
1. lmprove the ventilation, add heat sink to a few ICs.
2. Try to hack the scope to 100M BW.  Will try to through network connection.
Title: Re: BK Precision 2540B-GEN blank screen
Post by: tv84 on July 25, 2020, 04:55:01 pm
2. Try to hack the scope to 100M BW.  Will try to through network connection.

Should be the same as an old Siglent SDS. Maybe I can help.

Show us a picture of the System Info menu.
Title: Re: BK Precision 2540B-GEN blank screen
Post by: Galen on July 25, 2020, 10:06:06 pm
Thanks a lot tv84. I will take a picture of the system info screen in a few days (I am currently out of the city).
BTW, the scope looks like Tonghui TDO3062B/S.
B&K precision product link, scope was introduced in Y2012.
https://www.bkprecision.com/products/discontinued/2542B-GEN-100-mhz-1-gsa-s-digital-storage-oscilloscope-with-arbitrary-waveform-generator.html (https://www.bkprecision.com/products/discontinued/2542B-GEN-100-mhz-1-gsa-s-digital-storage-oscilloscope-with-arbitrary-waveform-generator.html)
https://www.bkprecision.com/products/oscilloscopes/2540B-GEN-60-mhz-1-gsa-digital-storage-oscilloscope.html (https://www.bkprecision.com/products/oscilloscopes/2540B-GEN-60-mhz-1-gsa-digital-storage-oscilloscope.html)
Title: Re: BK Precision 2540B-GEN blank screen
Post by: Galen on July 25, 2020, 11:08:10 pm
Found the system screen in the user manual. They are same except company name.
Title: Re: BK Precision 2540B-GEN blank screen
Post by: tv84 on July 26, 2020, 04:42:43 pm
Do you have a copy of the FW (any version)?
Title: Re: BK Precision 2540B-GEN blank screen
Post by: Galen on July 26, 2020, 09:52:39 pm
Yes Sir.  Downloaded it a few days ago from B&K Precision website.  Today, when I checked in B&K's website, it disappeared from the download list! At least I got 1 copy.
Title: Re: BK Precision 2540B-GEN blank screen
Post by: tv84 on July 27, 2020, 06:04:55 pm
I thought that your scope would be similar to a Siglent, looking at this:
https://www.youtube.com/watch?v=avd3SqRdJEg (https://www.youtube.com/watch?v=avd3SqRdJEg)

But, from the FW that you shared, I can see that the FW is totally different from Siglent. So I can't help you, sorry.

It's a Blackfin processor so it's not impossible to do some patching in the model to make it 100 MHz BUT I don't know details about the FW format (at least, it doesn't' appear obfuscated/encrypted like Siglent's).
Title: Re: BK Precision 2540B-GEN blank screen
Post by: Galen on July 27, 2020, 10:28:37 pm
Dear tv84, actually, you already helped me by providing these information. So, thank you very much.
I remember it's main board picture is different from the one you shared above. I will put one here.
Yes, I guess changing it's model number should works. So will see if some command, like 'set model 2542B', works or not.
firstly, using *IDN´╝čto confirm the communication.
Title: Re: BK Precision 2540B-GEN blank screen
Post by: Galen on July 28, 2020, 11:30:19 pm
Tried 'IDN?' , the scope reply it's ID 2540B-GEN, so network communication is good.  But tried a few commands to set the ID, restart the scope, no joy.
Where to find the right command to set the  scope model ID?
Title: Re: BK Precision 2540B-GEN blank screen
Post by: Galen on August 24, 2020, 01:44:14 pm
The CPU is Blackfin BF531. very similar with Rigol DS1052E.  Any suggestion to hack the firmware? Very appreciate any suggestions.