Unless you have an oscilloscope you cannot do much, however, with a simple VM you can get an idea, -0.6V.
Check the following : FRONT: C36, C37, C38, C39 , U18, U16 Back: Check image.
What "afedorov" suggested is correct however you need to have the correct voltage to worry about any other issue.
1> Have you checked for any possible short circuit? 2> Are all components in the correct position and polarity? 3> Have you tested all PINS on all chips that are all connected with a good solder joint?
1，i chencked triode,they are not short 2.position are correctly 3,i test all chip's pin to scl, sda, 3.3v,they are ok
Here are some of my work yesterday The picture you provided shows the generation of 3.3V and - 0.6V voltage. After I measure it separately, it outputs 3.28v and 0.56v. Maybe this is a reasonable error range? Yesterday, I removed all the chips connected to SCL and tested the voltage change. When I remove U12, 13 and 18 at the same time, the original voltage connected to the front board changes from 3.17v to 3.23. Is this reasonable or is U12, 13 and 18 faulty? At the same time, I inquired about the working voltage of the U8. It only needs 2.5V to work, so the current voltage of 3.17v does not seem to be a problem. I have an oscilloscope, if you can, please give the test method, although I have an oscilloscope, but I rarely use it, do not understand it.
My work -0.689 all time and voltage is stable no matter what I do. I would check all diodes & transistors that are on the correct assignment, also I would check for shorts on the -0.6v rail.
How do I check? I checked the triode, their pins have voltage, but I don't know how to make sure they are working properly I replaced the cable, and nothing changed
Yes, that is a good way to verify that all diodes are doing the correct rectification The voltages have to be in that exact range of figures. Replace what you think might be wrong and let us know good luck.
i test voltage,if only use back,it seems ok.when i connect front,something goes wrong.you can see the pictuer.the voltage be pulled down about 0.1V.
I suggest putting everything as it says in the BOM and checking all voltages that are correct. I notice you are using DC from the photos, have you tried AC?
Re BOM missing stuff it is not the case, just make sure to get the correct pitch size with it is 2.54mm. J4, J8 2 CNTR Header, 10-Pin CABLE HEADER 2x5 2.54mm 2x5x2.54
OK，i will changge resistors and diodes, and wires. Is the picture you provided to let me check the 6pin socket?
Your front board is ok, but I would use 10M ohm. I notice you remove U11, did the error 45 still persisting?
There is nothing wrong if you solder crimp pins but it is not recommended since the wires will get lose eventually especially if it is in a vibration environment or while testing, the wires with solder will get solid and will no longer be flexible therefore they will be very fragile and snap so the crimp is the best way to solve such issue.
Thanks for the photo, besides the diodes, did you take any other shortcut?
That is designed for a 10p ribbon cable IDC any reason why you use that type of connector they cost pennies 3 RMB? By any chance have you solder those crimp pins? If yes, you are asking for trouble, if you want that type of connector make sure you use the correct Crimp tool.
Re Wires vs Ribbon not sure if that creates any possible noise or interference.
I didn't find the 10PIN socket in the BOM, so I bought and soldered the socket and plug myself. I used the multimeter to measure the wiring. Maybe they have some problems as you said. Only rectifier diodes and a 10 m ohm resistor, I used a 3 m ohm through-hole component.
If this is a new assemble please check the ribbon cable and check it using a multimeter for continuity to see if pin 1 is going to pin 1 and so on. Error 21 is normal to be displayed for less than 1 sec (10 ms +-).
It's a new assembly, and 21 has been around for a short time. I've checked the connection many times and it seems to be OK。this is my connect
I have a problem. When I power on, 21 will be displayed and then 45 will be displayed. I checked the thread in the past and replaced the U8, but the fault still exists. Any suggestions?
