Have you read through Banggood's forum posting?
http://forum.banggood.com/forum-topic-61279.html?page=4
Search found 78 matches
- Wed Aug 19, 2015 8:37 am
- Forum: DSO138
- Topic: Sellers reported selling FAKE DSO138 kits
- Replies: 70
- Views: 278320
- Wed Aug 19, 2015 8:35 am
- Forum: DSO138
- Topic: Sellers reported selling FAKE DSO138 kits
- Replies: 70
- Views: 278320
Re: Sellers reported selling FAKE DSO138 kits
Now that is interesting. I believe that the voltage at TP25 and at L1 vary depending on the actual value of L1. If you put your finger on the probe can you pick up AC hum floating around your workbench?
Did you contact Banggood about the fake board?
Did you contact Banggood about the fake board?
- Mon Aug 10, 2015 7:56 pm
- Forum: DSO138
- Topic: Q1 Exploded
- Replies: 5
- Views: 7495
Re: Q1 Exploded
Check your board first http://www.jyetech.com/forum/viewtopic.php?f=18&t=511 . Seems that wrong value inductors are either common or a fact of life on the counterfeit boards. You would need an inductance meter. If you do have a counterfeit board perhaps the easiest option is to buy the correct v...
- Mon Aug 10, 2015 11:11 am
- Forum: DSO138
- Topic: Q1 Exploded
- Replies: 5
- Views: 7495
Re: Q1 Exploded
Are you sure you have a "real" DSO138? Check the value of L2.
- Wed Jul 29, 2015 7:28 am
- Forum: DSO138
- Topic: Test is not square
- Replies: 13
- Views: 16944
Re: Test is not square
Glad you are making progress. The test signal should be OK in AC or DC, but you have to be able to adjust the vertical position and to be able to reduce the sensitivity enough to get the whole waveform on the screen. A good "shotgun" technique is to re-solder ... in your case the input/ana...
- Tue Jul 28, 2015 7:12 pm
- Forum: DSO138
- Topic: Test is not square
- Replies: 13
- Views: 16944
Re: Test is not square
3mA? Is that the current drawn by the DSO138. It should be around 130mA. I'd suggest, seeing as we can't determine that the test signal point is working going back to the 10VAC source from your transformer and working with that as a test signal. Are you able to the Vpos alignment with no input signal?
- Tue Jul 28, 2015 10:30 am
- Forum: DSO138
- Topic: Test is not square
- Replies: 13
- Views: 16944
Re: Test is not square
:? :roll: :cry: Well, there can only be an open track from pin 17 (TESTSIG) on the uP to the end of R26 or a short on this track. Do a close visual inspection to confirm pin 17 is soldered to the PCB track and that there are no shorts on the track to R26. R26 could be open and/or you have shorted pi...
- Tue Jul 28, 2015 8:55 am
- Forum: DSO138
- Topic: Test is not square
- Replies: 13
- Views: 16944
Re: Test is not square
Test signal ... if it is not on TESTSIG end of R26 you have microprocessor problems. You will need another oscilloscope to look for it. How about measuring all the other voltages around the board. When you had the 10VAC source on it what amplitude do you read on the screen, even though you can't see...
- Mon Jul 27, 2015 10:34 pm
- Forum: DSO138
- Topic: Test is not square
- Replies: 13
- Views: 16944
Re: Test is not square
Sorry, I didn't realise that you were trying to look at the built-in test signal! Well, either the test signal is not on the test output or you have some issues in your input circuit. I was also confused by the top waveform. If you expecting 50Hz and getting that waveform what timebase setting are y...
- Mon Jul 27, 2015 7:29 pm
- Forum: DSO138
- Topic: Test is not square
- Replies: 13
- Views: 16944
Re: Test is not square
Can you display the built-in test signal?