Samsung G3 Series 3.5 Inch USB-Sata Adapter Repair
Recently my busy computer user friend Marco asked me to check upon his no longer working Samsung G3 series 3.5 inch USB to Sata adapter board.
Because I at first had no clue what he had brought me I started by examining all passive components. Made some photos and measured all values. Here follows the list I made:
Also C52 above U4/G5795 was nc. And position L1 left next the dual mosfet was nc too. (nc=>not connected).
After a quick examination I found no bad or broken resistor nor any bad capacitor component. And I started to check the active components being the step down DC DC converter G5795, the 93LC46B1 serial eeprom, and mosfet AP4957 with transistor Q3 with smd code DAYS.
I couldn’t find any info on the G5795 converter, maybe again because of infringement of some firm’s copyright?, but I assume that the given datasheet of a G5796 resembles the exact same functions. Because that type was constantly given at any Google search. Next photos show this board.
Naturally I also tested the USB to Sata adapter board by inserting a brandnew Sata 260GB SSD hdd and by connecting an 12V DC adapter to the power input jack. And connecting a USB cable to one of my USB ports of my Quad-core desktop computer. But as expected nothing happened. My computer still didn’t see the attached SSD drive.
So I started to measure the output voltages of the step down converter but assuming it should at least give a 3.3V DC output, there was nothing measured. Also the coil with marking 100 wasn’t giving any output voltage. Below an extract of the assumably pin compatible G5796 datasheet:
And after a quick ‘hot spot’ test, by just using my fingertips, I noticed that the G5795 chip was getting abnormally hot. Which explains why the bigger square controller IC with marking JMB509 couldn’t work and also the sop8 93LC46B1 serial eeprom couldn’t be read by the JMB509 either.
Also finding a datasheet of this JMB509 was impossible, probably again because of some copyright issues with Samsung, who sells and probably designs these small adapter boards? And testing this chip was simply not possible other than just checking it by trying to fix the culprit on this defect board.
And I did a quick transistor Q3 measurement by using the diode beep test on my DMM. And I also assumed that the dual 7,4A 20/30V P-channel Mosfet was still intact.
Next I desoldered the sop8 serial eeprom from the board to check its function by trying to read its content by using my new GQ-4×4 USB programmer and a smd to dip socket adapter. Next screen copy shows that the 1K eeprom was still just completely fine! The screen also shows the successfully extracted 1K bin file.
About this new GQ-4×4 Universal Programmer : I bought it because I needed to make sure I could read,copy and save the calibration data of the battery backupped SRam’s in my Tektronix oscilloscopes. I managed reading all 8192Bytes of the 4464 in my Tektronix 2465A with my TL866II
and a special made 28 pins cable with IC test clip, but it gave verify issues reading the Dallas 1225y or the FM16(w)08 memory chips. Why I needed a better programmer which is the new GQ-4×4!
Although both programmers still not support all of these SRam or battery backed up Dallas memory chips and neither the Ferro Magnetic FM16(w)08 and the larger 18(w)08 (for the 2440 Tektronix oscilloscopes). GQ-4×4 does support the Cypress FM16(w)08 Rams but fails to support the almost identical (both firms are now one?) Ramtron FM types. And also the 18(w)08 types altogether. But perfectly supports all Dallas 3V lithium backupped modules! And sadly also the RT809H, and the TL866II still need many more upgrades supporting all those types too! But if the FM types are not available they possible still can be read as a Dallas DS1225 memory type. The RT809H however can’t read any of the Dallas DSxxxx memories! Why we simply need several universal programmers to fill the device supporting gap! (Why I already count now having 5 of those different universal programmers, and also several different smd to dip and other IC adapters).
Next picture shows part of datasheet of this 3-wire 1K serial eeprom that according to its specs is capable in providing at least 1000.000 secure read/write operations! And a retention time of over 200 years!
And the datasheet also shows several different chip pin configuration settings. The nice thing of using an universal programmer is that we normally do not need to bother with using the right setting because we just insert the chip into its smd to dip adapter with pin 1 in the right direction and we are good to go! And if we do not get any good read or verify we simply check and adjust our chip or chip setting.
As I already wrote in the earlier given component list, the likely 3.3V output of the 100 marked coil goes to the source 2 pin of our AP4957 dual mosfet. And a page of that datasheet follows.
Next an extract of the AP4957 AGM P-channel dual mosfet datasheet. It is obvious to assume that the D2 output is giving no voltage out because there is no output voltage at pin 3 of the step down IC G5795. Strangely these G5795’s are still plenty available on Aliexpress although there is no datasheet available. Like happened in another 230VAC to 5V USB adapter repair I wrote that was about a defect unknown ‘data protected’ sop6 PWM controller chip from a firm that used these in their special power unit devices.
On 10 May ’21 I ordered five of those G5795 3.3V DC DC step down sop8 chips for about +3 Euro including shipping on Aliexpress.
I am almost certain that replacing this ‘specs unknown’ chip will fix this small USB to SATA adapter board! And the herein given information will no doubt be most useful for other Samsung G3 series 3.5 inch Sata converter owners.
Update: On this link afterwards the exact datasheet for the G5795 was found. It is indeed pin compatible and has the same function but works on a lower 340KHz frequency, instead of the 500KHz of the G5796 and higher types. Strangely the datasheet of this IC is always only one page, and there should be more!
In the meanwhile my friend got in contact with Samsung to claim a new adapter board. But all they thus far said was that it shouldn’t have happened so soon and that it was quite unexpected. Anyhow, no matter how the service of Samsung turns out to be, as soon as the new G5795 DC DC step down converter is here, I expect that his old Sata board will be working like a brand new one!
Albert van Bemmelen, Weert, The Netherlands.
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Note: You can read his previous repair article in the below link: