mercury pc power supply only 5vsb supply.

[playit]

Re: mercury pc power supply only 5vsb supply.

is it totally damaged? no way to fix it?

[playit]

Re: mercury pc power supply only 5vsb supply.

oh damm.. so its not because of low volt 200v (before it was 250v) in the filter capacitor big ones? anyways to fix them.. ?

[R_J]

Re: mercury pc power supply only 5vsb supply.

It looks like the mosfets in the primary shorted and blew the gate resistors and diodes, and likely the two small electrolytics were bad as well.

[playit]

Re: mercury pc power supply only 5vsb supply.

hi ,hope you are in good health.. after a long time,i got my shipping.. so i fixed c945 ,fixed it all.. it worked for 2 secs then boom boom ,flashes came.i switched it off immediatly.. please see the pics ,what happend.. i think primary side resistors busted off ,it was fun tho.. atleast i made it work for 2 secs lol.

[R_J]

Re: mercury pc power supply only 5vsb supply.

The 2sc1815 should work fro the h945

[playit]

Re: mercury pc power supply only 5vsb supply.

i have this transistor available ST2SC1815 ,almost similar parameters except these 2 - ft is 250 for h495p ,80 for ST2SC1815, power dissipation is 250mW for h495p , 400mW for ST2SC1815
can i replace h495p with ST2SC1815 ?

[playit]

Re: mercury pc power supply only 5vsb supply.

they have nothing in the shop,they dont know anything.. hate these guys,,i have to order online now.

[playit]

Re: mercury pc power supply only 5vsb supply.

i cheked the diodes ,with black probe in between and difference at either sides come almost same sometimes or 1 value difference. 40-39 ,39-40.. 28-29 ,guess they are ok
oh and i removed some 4148 near the transistors which gave short beep with no value. but after removing they checked to be normal ,really as you said damm beeps are nothing!

[playit]

Re: mercury pc power supply only 5vsb supply.

yes ,you were right,i saw some youtube vid ,saying the continuity in diode cant be reliable,you have to remove it to test it properly, i was thinking to buy and keep just in case as my shop here is at 1 hour distance.was planning to go there today..
oh ya i removed it outside ,both of test weird.. confused..
so going to get new transistors now,if may i get diodes too.

[R_J]

Re: mercury pc power supply only 5vsb supply.

The two transistors you checked should read about the same. The fact that one checks different shows there is a problem, remove the transistors and check them out of circuit.

the vertical at base- continuous beep - black at base- continuous beep-value decreases- o-1812

This confirms the beeping is meaningless. the resistance of 0Ω or 1812Ω produces the continuity beep. so how in the hell can you go by that?

[R_J]

Re: mercury pc power supply only 5vsb supply.

It is likely the diodes are ok, you are being fooled by the meter beeping. I keep telling you you can NOT go by that. YOU NEED TO READ THE FARWARD VOLTAGE DROP when using the meter in diode test. Schottky diodes have a lower voltage drop (0.2xx) not (0.6xx)

[playit]

Re: mercury pc power supply only 5vsb supply.

would need little clarity on choosing substitutes by the ratings on
stth1002ct -this is Fast Recovery Rectifiers 200v, 8x2 16A,fv -1.25 V
stps2045ct - this is Schottky Rectifier vrrm -45v, 10x2 20A ,vf- 0.84 V

how nearest i can get a component less or high.. ,which parameters to choose ?

[playit]

Re: mercury pc power supply only 5vsb supply.

hmm the beep is just long continuous never ending..
also can i use high ampere transisitor ,h945-p is
Type - NPN
Collector-Emitter Voltage: 50 V
Collector-Base Voltage: 60 V
Emitter-Base Voltage: 5 V
Collector Current: 0.15 A

i might get 50v but different amperes like 2A
is it ok to replace wtih it?

[R_J]

Re: mercury pc power supply only 5vsb supply.

whats piece of string?

It is like a beep from a meter

[playit]

Re: mercury pc power supply only 5vsb supply.

What is the voltage drop of a BEEP? What is the resitance of a long BEEP vs a short BEEP?
If the diodes and transistors are checking shorted, replace them.
How long is a PIECE of string?
Check the internet for susbstitute diodes, I am not going to look for a replacements, Why are you replacing them? Are they shorted?

whats piece of string?

[playit]

Re: mercury pc power supply only 5vsb supply.

i just saw a video in which the schotty diodes at output side gave continuity long beeps (meaning short) even when power supply is working good, they say it happens sometimes but have to remove it to test it to see if it really is good or bad,so i am thinking of just changing the transistors and 4148 diodes

[playit]

Re: mercury pc power supply only 5vsb supply.

if i touch both of the multimeter leads i get long beep as its called shorting (source - youtube videos),so when i touch the legs of transistor ,i get the same beep as shorting..

the transistor-- the horizontal - black at base- 676- 699
reversed gave- red at base -1749 - 1852
the vertical at base- continuous beep - black at base- continuous beep-value decreases- o-1812
reversed gave - red at base- continuous beep value 0 - 362

[R_J]

Re: mercury pc power supply only 5vsb supply.

What is the voltage drop of a BEEP? What is the resitance of a long BEEP vs a short BEEP?
If the diodes and transistors are checking shorted, replace them.
How long is a PIECE of string?
Check the internet for susbstitute diodes, I am not going to look for a replacements, Why are you replacing them? Are they shorted?

[playit]

Re: mercury pc power supply only 5vsb supply.

some diodes at output section on heatsink = stth1002ct gkdsnvu chn816, and stps2045ct 7sacdvw phl 806(2 in numbers)
could you tell me what alternatives i can use if i dont get these?

[playit]

Re: mercury pc power supply only 5vsb supply.

i removed the jumper wire and checked the voltage ,it was still 0.76v . also checked the (c15)yellow color capacitor g104m (cant find what it is in internet) - value in diode mode- 576 stable , reversed - 1868(in some thousands) then disappears.
the diode (D11) 4148 is good.
i am using this multimeter- DT380D( just incase may be of somehelp)
the 2 transistors - Q5 is attached to jumper, Q6 attached to +ve of D13(ph4148) ,and there is a D12 at back of Q6.
these diodes are all short,giving continuity(long beep).
transistors giving beep too ,before it dint give beep.. saw some vids according to my multimeter.. it said its a sign of continuity and its short.
the transistors are H945P 8B3,if its not available what should i get instead? i was waiting for you reply,thanks a lot for showing up