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| JYE Tech DSO150 oscilloscope troubles |
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| MrElectric:
Just for fun, I bought a JYE Tech DSO150 oscilloscope from Banggood. I thought it would be a fun soldering project that might be usable sometimes. When it arrived, I read the instruction, which says to verify that it boots before soldering anything. Else the warranty will be void. I found a 9V power supply with center positive as instructed. I connected the power. The screen gets light, but nothing happens. After a while, I smell that something is getting hot. I remove the power and can feel that the large IC is really hot. I first thought the power supply might be faulty. So, I connect my power supply instead. Exactly 9V. I didn't think to turn down the current limit on the supply. After turning it on, it lights up exactly like when I used the power supply. Light screen, and a red diode on the backside. Then I notice that it delivers 1.5A through the circuit, and I see some smoke after a few seconds. According to the manual, it needs 400mA. I reported this to both Jyetech and Banggood. Jyetech send me a replacement. Banggood sent me another complete kit because I had received a bad unit. The new ones arrived yesterday. I first tried the one Jyetech sent me (with the same power supply as last time - I have verified it since). Lo and behold, it boots up, and the screen looks as expected. I try the same thing with the other one, but it's as dead as the first one I received. I now try the Jyetech one once more, and now it won't boot again... So, I set up my power supply again. This time, I use the current limiting. I set it at 200mA first. I test all three boards, and none work. I up the current to 400mA. Now the red diode glows dimly on one, but not on the others. I up the current to 600mA, and now the red diode shines brightly. As I didn't have a schematic, I did do some measuring. The input is 9V, and then there's a voltage regulator which outputs 3.3V. There is a pad that says 3.3V. This looks like a good spot to measure the voltage. I can see no consistent results between the three boards. None of them measure 3.3V there though. Using the continuity tester, I see that there is a short between all legs of the voltage regulator and ground on two of the boards. The third has 174 ohms between ground and 3.3V, while the others have 0.5 ohms (or thereabouts). Clearly, there is a short somewhere, that makes the voltage regulator get hot. On one of the boards, it's the big IC that gets hot, while on the other two, the voltage regulator gets hot... Anyone else with this problem? I seem to find a number of positive reviews of this unit. [edit: I removed the negative comments. I understand more of the circuit now, and believe the margin for over-voltage wasn't enough. Many power adapters give out much more than 9V when unloaded. The voltage regulator only handles up to 15V. They are going to release a new version with a 5V USB power connector instead, which will make for a better tolerance to over-voltage] |
| Peabody:
I built the Shell scope, and it has worked very well. From what I hear, I think your experience is not at all typical. In fact, having the same failure on three units from different sources would be extremely unlikely. From your description it seems the only thing in common in all three cases is your power supply. Have you considered trying it with a 9V battery? My DSO150 is the original version, and it draws about 120ma. They've made some improvements since then, and I don't know what the newer units draw. I really don't think these units are junk at all. A good bit of engineering goes into them, and the manuals are well done. And they have continued to issue firmware updates from time to time, which is unusual for products of this type, and as you have seen, they stand behind their products. JYETech is about to release a two-channel version of the DSO150, and if the price isn't too high, I plan on getting one. Of course I can't tell from here, but logically it seems something at your end is more likely the problem. By the way, there should be a schematic included with the unit. If not, schematics are available for download on the JYETech.com website. |
| MrElectric:
I found this instcruction, where someone has similar problems (after using a 12V AC adapter): https://www.instructables.com/id/DIY-Oscilloscope-Kit-Assembling-and-Troubleshootin/ I now see I wrote "power supply" everywhere yesterday. I need to clarify that. When I got the first one, I first couldn't find a 9V power adapter, so I used my lab power supply, set to exactly 9V (tested with a multimeter as well). It had the same symptom then, i.e. white screen, red diode. I only did this for a short while, because I didn't find a place where I could attach the +9V clip, so I had to hold it in place while testing. I then found a 9V power adapter that I used after that. Same symptom. After a while the large IC got hot. I then switched back to the lab power supply because I wanted to be sure I supplied the correct voltage. I left it running like this for 10-15 seconds, when some component (maybe the voltage regulator) blew up. When I received the new units, I used the 9V power adapter. The first one booted up ok, and I don't think that anything got hot. The second one didn't boot up at all, same problem as unit 1. Next time I tried unit 2, it didn't boot up. I have since then tested with the lab power supply. I have now found the schematic online. It was not included in any of the units. |
| Peabody:
Well it just seems unlikely that three units would be bad. As you said, the reviews are generally quite good. But as confirmed on the link you found, powering it with higher than recommended voltage would be a problem. I'd strongly suggest you post about this on the JYETech forum, and see if anyone there has a suggestion. It sounds like a voltage regulator problem, but of course it could be something shorting downstream. Nothing on the board should get hot, and it shouldn't draw much over 100ma. I've converted mine to battery power with a charger and boost converter, and it still works fine after two years. I have found it to be surprisingly useful. My unit included a schematic, but they may have stopped doing that. The printed version was difficult to read, and I guess they decided the downloaded pdf would be more useful. I should say that there are some counterfeit units out there, but Banggood is known to have genuine supply. I got mine there. I hope you find a resolution. |
| NoisyBoy:
I received mine last week and just assembled it last night, everything works fine on it, no problem. I also think with three failure, it is likely that the problem could be related to power supply. I have powered mine with both an Agilent bench supply and a precision system power supply, the latest draws just about 100mA in normal operation. With such project, I always use a 300mA current limit to be on the safe side. I am surprised that the tiny scope did not burst into flame when it drew 1.5 A |
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