On K9MM-V MOBO is fried southbridge VIA VT8237R+
I have only working VT8237. Can it be placed on this mobo. I found that R marking is for RAID. Maybe only RAID will be disabled?
ASROCK 775i65g revG/A 2.03
MOBO is starting normaly, nothing is heating, only DDR voltage is lower than it should be. On start, voltage is 2.11V, then it start to rise until it`s 2.3V and then it drops it to 2.27V and there it stops to fluctuate.
In DDR supply there is only one MOSFET (that I changed of course), no voltage terminators or other chips. In BIOS there is no options to change DDR voltage.
All tests (PC mark, 3D mark...) working normaly without any problems.
Should I do something at all on this mobo?
Не верю, мосфет не может сам собой управлять.
About VT8237R+/VT8237 - here (may be some interesting).
About VDDR on ASROCK 775i65g - near mosfet - resistor network RNxxx (I'm not see number on photo :)).
Measure voltage on one side RNxxx and on other side RNxxx. Also measure voltage on gate VDDR mosfet.
Control scheme to this mosfet (VDDR) IMHO one of the two 14-pin IC (LM324 - my fantasy :)) near south bridge.
You were right, as always:)
There are two LM324 u15 and u14. Changing u15 resulted DDR voltage stabilised on 2.65V.
Thank`s a lot...
Без памяти на Q27: G - 4.57V, D - 3.38V, S - 1.82V, с памятью G - 4.57V, D - 3.38V, S - 1.98V
Если U15 имеет питание +5 В, то замените Q27 на транзистор с низким Vgs(th) - что-нибудь аля AP9916GH.
Если U15 имеет питание +12 В, то было бы интересно уточнить напряжение на неинвертирующем входе соответствующего ОУ.
APM'ы бывают разные, в следующий раз указывайте точную маркировку.[/off]