Chimei DAC-19M009 Power Supply problems

[caryg]

I've got a 22" Chimei branded monitor which seems to be fairly similar to the Westinghouse 19" which already has a long thread here, but instead of the 19M005 power board it's got one marked 19M009, and rather infuriatingly it looks like they've replaced the troublesome MOSFETs on that board with something marked P605 BD7C1F. Does anyone here have any experience with this board and any hints on where to look. The caps all look OK, and both the glass fuse on top and the little one underneath test fine. Here's a photo which may help

[PlainBill]

Re: Chimei DAC-19M009 Power Supply problems

I've got a 22" Chimei branded monitor which seems to be fairly similar to the Westinghouse 19" which already has a long thread here, but instead of the 19M005 power board it's got one marked 19M009, and rather infuriatingly it looks like they've replaced the troublesome MOSFETs on that board with something marked P605 BD7C1F. Does anyone here have any experience with this board and any hints on where to look. The caps all look OK, and both the glass fuse on top and the little one underneath test fine. Here's a photo which may help

What problem are you having?

PlainBill

[caryg]

Re: Chimei DAC-19M009 Power Supply problems

D'oh! I was making such a hash of trying to upload a photo that I missed that bit out. It's completely dead, no sign of life at all, not even a blinking LED.

[Krankshaft]

Re: Chimei DAC-19M009 Power Supply problems

Check those FETs they are the drivers for the inverter transformer think of them as the HOT of the LCD world they fail and fail often .

If they've been replaced once already I'd check for cracked solder joints in the inverter area. No need to deal with a repeat failure.

http://www.alldatasheet.com/datashee...D/AOP605L.html

To test DMM to diode check from source to gate reverse probes should only read in one direction from drain to gate same applies. There are two in one package. If you read a short then the IC is shot.

[PlainBill]

Re: Chimei DAC-19M009 Power Supply problems

D'oh! I was making such a hash of trying to upload a photo that I missed that bit out. It's completely dead, no sign of life at all, not even a blinking LED.

First of all,with the power supply plugged in (to both the monitor and AC power) CAREFULLY measure the voltage across the two pins of the large cap. I've circled them in red in the attached picture. This point packs enough of a punch to give you a jolt.

If you get either 150-170 VDC or 300-340 VDC the next step is to disconnect AC power from the board and unsolder 1 lead of the fuse circled in blue. Hook the board up again and see if the power LED works properly now.

If you still get nothing, it is time to take a picture of the area I have circled in green. Photograph both sides of the board. I am looking for any information on what voltages to expect.

PlainBill

[caryg]

Re: Chimei DAC-19M009 Power Supply problems

Check those FETs they are the drivers for the inverter transformer think of them as the HOT of the LCD world they fail and fail often .

OK, Assuming that the dot on the top of the FET marks pin1, and that they then run 1,2,3,4 up to the top then 5,6,7,8 down the other side, and according to the datasheet the pins are (from 1 to 8) S2, G2, S1, G1, D2, D2, D1, D1, then I get the following readings, pretty much identical on both FETs, according to which way round I have the DMM leads (Red/Black)

S1 Red to G1 805
S1 Black to G1 787
S1 Black to D1 663 (both pins)

S2 Red to G2 330
S2 Red to D2 614 (both pins)

Everything else gives no reading. S1/G1/D1 and S2/G2/P2 seem to be wired up in reverse, so I would expect them to conduct in opposite directions. I would guess that I shouldn't be getting the first reading listed, the S1 Red to G1, and therefore both FETs have blown. The fact that the S2 circuit reads only half the value (and I'm not sure what exactly I'm measuring here) would confirm it. It looks odd that they have both apparently blown the same way. Is this common, or am I mistaking something?

Thanks for the pointer to the FETs; now to hunt down a supplier.

[caryg]

Re: Chimei DAC-19M009 Power Supply problems

First of all,with the power supply plugged in (to both the monitor and AC power) CAREFULLY measure the voltage across the two pins of the large cap. I've circled them in red in the attached picture. This point packs enough of a punch to give you a jolt.

PlainBill

The big cap gives me nothing at all, which suggests that something on the mains side has gone. Looking closer I see that underneath the wire earthing the board to the mains socket there is a fuse marked T3.15A 250V CQ and under that MST JET. A fuse which has blown. Bearing in mind the clean state of the rest of the board I'm tempted to find a replacement and see what happens. Now I just have to get at the awkward little fellow.

[caryg]

Re: Chimei DAC-19M009 Power Supply problems

OK, it's not just a power surge that popped the fuse; I stuck another in there and that went the moment I plugged it in. Does that suggest that the faulty component is likely to be close-by? I'm not too sure where to look next. I had hoped that the dud fuse suggested that those FETs were really OK. Would they cause the main fuse to blow? Thanks for the help so far. I would never have realised that the little black box squeezed in under the power cable was a fuse. Is it normal to make them so inaccessible?

[PlainBill]

Re: Chimei DAC-19M009 Power Supply problems

OK, it's not just a power surge that popped the fuse; I stuck another in there and that went the moment I plugged it in. Does that suggest that the faulty component is likely to be close-by? I'm not too sure where to look next. I had hoped that the dud fuse suggested that those FETs were really OK. Would they cause the main fuse to blow? Thanks for the help so far. I would never have realised that the little black box squeezed in under the power cable was a fuse. Is it normal to make them so inaccessible?

Well, the days where a fuse was a user-replaceable part are long gone. In part, this was because users would figure that "if a 3 amp fuse blows, let's try a 15 amp."

There are several possibilities. The likely culprits are the bridge rectifier, the switching transistor driving the transformer, and the transformer itself. I'd suggest pulling each of them and testing with a DMM.

PlainBill

[caryg]

Re: Chimei DAC-19M009 Power Supply problems

The bridge rectifier was blown, so I stuck in one taken from an old PC PSU, changed the fuse again, and gave it a try and it all seems to work OK. Now the gamble is to stick with it as is and assume an outside surge blew the rectifier, or to keep exploring, and risk damaging the board with my pretty basic soldering/desoldering techniques. Thanks for helping me get to a working monitor.

[PlainBill]

Re: Chimei DAC-19M009 Power Supply problems

The bridge rectifier was blown, so I stuck in one taken from an old PC PSU, changed the fuse again, and gave it a try and it all seems to work OK. Now the gamble is to stick with it as is and assume an outside surge blew the rectifier, or to keep exploring, and risk damaging the board with my pretty basic soldering/desoldering techniques. Thanks for helping me get to a working monitor.

You're welcome.

Assuming you replaced the the fuse with one of correct value, there is no reason not to use the monitor. The most likely cause for the bridge shorting was a voltage spike. The second most likely cause would be excessive current.

PlainBill

[shane_newcastle]

Re: Chimei DAC-19M009 Power Supply problems

hello all this is my first post here and im sorry top revive an old thread but i thought it best seeing as though i have issues with this exact power supply

First of all,with the power supply plugged in (to both the monitor and AC power) CAREFULLY measure the voltage across the two pins of the large cap. I've circled them in red in the attached picture. This point packs enough of a punch to give you a jolt.

If you get either 150-170 VDC or 300-340 VDC the next step is to disconnect AC power from the board and unsolder 1 lead of the fuse circled in blue. Hook the board up again and see if the power LED works properly now.

If you still get nothing, it is time to take a picture of the area I have circled in green. Photograph both sides of the board. I am looking for any information on what voltages to expect.

PlainBill

im getting 350vdc at the cap tried unsoldering the fuse no change
in the area in blue there is a 13.8v out put which is reading 14.29v
but the 2 outputs marked 5v are reading nothing
any help in this matter would be greatly appreciated

[PlainBill]

Re: Chimei DAC-19M009 Power Supply problems

hello all this is my first post here and im sorry top revive an old thread but i thought it best seeing as though i have issues with this exact power supply

im getting 350vdc at the cap tried unsoldering the fuse no change
in the area in blue there is a 13.8v out put which is reading 14.29v
but the 2 outputs marked 5v are reading nothing
any help in this matter would be greatly appreciated

I assume you are in an area where line (mains) voltage is about 240 VAC.

Troubleshooting this would be much easier if we had sharp, clear pictures of both front and back sides of the board. Take the pictures in a well lit room and turn the flash off. It will probably be necessary to trace out part of the circuit.

Also, post a picture of the connector indicating the voltages specified and the voltages you found.

PlainBill

[zac_haryy]

Re: Chimei DAC-19M009 Power Supply problems

Hey all, new to the forum but having close to the same issue. When I plug in the monitor I get a green light and a high pitch noise and then after a bit (5 seconds) the screen turns gray. I was trying to figure out what part on the power supply this was? I have tried doing a little research on a bridge rectifier or find out which part that is but have had no luck. Anyways some help would be great!!

-haryy

[gothelder]

Re: Chimei DAC-19M009 Power Supply problems

First of all,with the power supply plugged in (to both the monitor and AC power) CAREFULLY measure the voltage across the two pins of the large cap. I've circled them in red in the attached picture. This point packs enough of a punch to give you a jolt.

If you get either 150-170 VDC or 300-340 VDC the next step is to disconnect AC power from the board and unsolder 1 lead of the fuse circled in blue. Hook the board up again and see if the power LED works properly now.

If you still get nothing, it is time to take a picture of the area I have circled in green. Photograph both sides of the board. I am looking for any information on what voltages to expect.

PlainBill

Greetings

I have the same flavor of board with the same component configuration as far as I can tell.

I was able to test the fuse for continuity and there is no resistance so its not blown. (This is the one circled in blue)

I measured the VDC across the capacitor right near the power plug and got 172. I tested the other capacitor as long as I was in the guts of the beast at it read 17.

The fuse the other poster mentioned on mine appears to be fine. I was able to test the continuity across it on the back of the board and had 0 resistance.



and

[PlainBill]

Re: Chimei DAC-19M009 Power Supply problems

Greetings

I have the same flavor of board with the same component configuration as far as I can tell.

I was able to test the fuse for continuity and there is no resistance so its not blown. (This is the one circled in blue)

I measured the VDC across the capacitor right near the power plug and got 172. I tested the other capacitor as long as I was in the guts of the beast at it read 17.

The fuse the other poster mentioned on mine appears to be fine. I was able to test the continuity across it on the back of the board and had 0 resistance.


and

First problem: Read this.

Next, you have at least 5 bad caps.

PlainBill

[gothelder]

Re: Chimei DAC-19M009 Power Supply problems

First problem: Read this.

Next, you have at least 5 bad caps.

PlainBill

Greetings again.

I figured that the canisters sitting upright should not have the tops be bowed out like that. The last time I was in the guts of a piece of equipment was in the 80's. (I really really like this monitor though). Hopefully it does not turn out its only botulism

I was hoping it was only a fuse but that was not to be, that I can replace in most circumstances, but when it comes to heavy duty soldering I know just enough to be dangerous.

Apologies for using offsite hosting but the images were too big for the badcaps.net hosting.

I will shrink them a bit and repost them in this reply so that they are hosted onsite. I expect they no longer need to be as DPI intensive as your likely to have already cracked it as it were.

Thanks for your response.

[plugh]

Re: Chimei DAC-19M009 Power Supply problems

Another Chimei DAC-19M009 here...

not mine, a friends; he said display went black.

Told him to try switching dvi vs vga; no change.
Told him to use flashlight; can see ghost image.
Told him to adjust bright/contrast;
... with control turned down display sometimes lights on powerup up.

He opened unit up, pulled PS board, brought it over.
(It is the same board and rev as in preceding post)
Inspection reveals board discoloration around P605 inverter ICs,
and 3 * CapXon 220uF 25V 105C 'KF' caps with bowed tops.
(one by glass fuse, one between horiz cap and vert resistor,
one between large green cap and regulator in above pic)

Diode checked the P605's - they seem OK.
(thanks for the datasheet pointer above)

Another thread here gave pointer to CapXon
http://www.capxongroup.com/en/prod_all_cat_full.aspx
The 'KF' datasheet says 220uF 25V is low impedance, 8x11.5

A local warehouse outlet (MCM Electronics) listed two 220uF 25V radial caps
31-7090 - Capacitor 25V 220uf 105c HI Temp,radial (8D X 11.5l MM) $1.09
31-5550 - Capacitor 25V 220uf Low ESR Hitemp, Hifreq. Rad. 8dx15l MM $1.89
unfortunately the 5550's were on backorder (21 days out), but 35V wasn't
31-5685 - Capacitor 35V 220uf Low ESR Hitemp, Hifreq. Rad. 8dx20l MM $2.19
(these are a LOT taller than the CapXon's but will still fit ok)

web-ordered and picked-up 3* 7090 and 3* 5685

Upon inspection, 5685's are Nichicon 'PL' series.

Markings on 7090's are 220uF 25V 105C GE with 76P4 stamped on side and
'M in a box' symbol (M looks more like a capital Sigma rotated 90 degrees)

Anyone know who / what this cap is? Specs / datasheet?

Or should I just go with the Nichicons? Note spec diffs:
CapXon KF 25V
---ripple 550mA rms at 105C 100KHz
---impedance 0.15 ohm at 20C 100KHz
Nichicon PL 35V
---ripple 795mA rms at 105C 10KHz~200KHz
---impedance 0.085 ohm at 20C 100KHz

Thanks!

[plugh]

Re: Chimei DAC-19M009 Power Supply problems

from this page
How to Identify Japanese Electrolytic Capacitors
it appears 'M in a box' symbol is for Panasonic (Matsushita)

Now to see if I can track down specs on the 'GE' series...

[lucky13]

Re: Chimei DAC-19M009 Power Supply problems

Wow, Malware on that imageshack site posted by gothedler?

Ctrl-F4 killed it....