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train123_not logged on
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 Posted: Tue Nov 23, 2010 3:49 pm Post subject: Test mode |
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| playedataritoday wrote: |
I was just given an Viewsonic N3252W to try and repair.
It was working for a while on tuner mode and then got stuck on one of
the inputs and would not allow for it to be changed. It was used like
this for a few weeks and then got stuck running the test pattern where every 5 seconds or so a different color screen would show up and then
sometimes the full color bar test pattern. This is the point it was given to me. To turn it on, we need to use the remote and the only way to turn it off is to pull the plug.
I took the back off and took the following measurements at power supply connectors both when the unit is on and when it is in standby.
CN102
On (Standby)
1 - 12.09 (0)
2 - 12.09 (0)
3 - GND
4 - GND
5 - GND
6 - GND
7 - 5.11 (5.11)
8 - 5.11 (5.11)
9 - 5.11 (5.11)
10 - 3.47 (.062)
11 - 3.57 (.627)
12 - 4.87 (.006)
CN101
On (Standby)
1 - GND
2 - GND
3 - GND
4 - GND
5 - 23.75 (0)
6 - 23.75 (0)
7 - 23.75 (0)
8 - 23.75 (0)
9 - 3.57 (.627)
10 - 4.87 (.006)
I removed the power supply completely and can see no evidence of
faulty capacitors and the voltages all seem to be in range. My only
concerns is CN102 - pin 10, being 3.47V, although I don't have
the schematics so I am not sure what it should be. I might have
expected something closer to 5V.
At one point using the top switches I was able to finally change the input
mode to VGA, and I was able to drive with a netbook and it gives me a
beautiful picture. Although now I am unable to change it to anything else, and the OSD window for "Main:" stays on the screen.
The voltages at P701 (top side switch board) are as follows:
On (Standby)
Orange - 0 (3.77)
Blue - 3.74 (3.77)
Red - 3.74 (3.77)
Green - 3.74 (3.77)
Yellow - 3.74 (3.77)
Black - 0 (0)
Brown - 3.74 (3.77)
Now I have seen a lot of discussion in this thread possibly pointing to Q7/ZD4. Now this might be a simple question but which board is this on, the PS or the logic board? I don't see any reference designators for Q7 or ZD4 on either. Even though this is an N3252W, my power supply does not seem to be the FSP 212-3F01/02 every is mentioning. The Darfon part number of mine is: 4H.B0350.001 / D2 and the label on the other side indicates it might be: BK0103500106 B40 S000547 2200232015P Rev A.
Does anyone have experience with my specific issues and has anyone seen similar symptoms with their set? I have no problem replacing the surface mount components (provided I can ID them on the board) or even as a second step dropping money on the replacement supply, I just want some confidence the problem isn't something else before I invest anything more than my time. Also since my power supply seems to be a different revision if it comes down to it, is the Power-On version with the adapter cable still the right one?
All help is appreciated.
Stephen
playedataritoday@gmail.com |
Lcdtech posted this tip on Jan 25, 2010
1. the service manual says "check voltage on C101 16V if not replace power PCB but if one goes into a special mode (cycles primary colors on the LCD panel, can be entered into by pressing MENU + ENTER + Power button) it seems that the backlights work, colors cycle normally, etc. |
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jc00
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| Posted: Tue Dec 07, 2010 5:59 pm Post subject: FSP228-3F01 need R58 value. |
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Hi,
I need to know the value of R58, located by Q2, on FSP228-3F01 power supply. It is cracked and I can't read its value. This is the last step, after following all recommendations on this thread, for my Viewsonic to work again.
Thanks for the help!
JC     |
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svalle.00
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| Posted: Wed Dec 08, 2010 7:44 pm Post subject: thanks to all |
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Hi guys, following the recommendations (changing all bulging caps and ZD4/Q7) my viewsonic is now working for... an hour I think...
the symptoms in mine where:
-- the red standby led blinked nonstop when plugged in.
hopefully this could help someone in troubleshooting....
thanks!! |
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jc00
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| Posted: Thu Dec 09, 2010 1:35 pm Post subject: R58 |
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| Hi Svale, any chances you could give me the numbers on R58? |
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xVsonicDis
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| Posted: Sun Dec 19, 2010 7:24 pm Post subject: Garbage TVs |
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| I was a view-sonic resaler for a few years for monitors and they seem to be good. Then I purchased a TV and now have replaced the power supply 3 TIMES over 5 years. This last time it lasted 1 year without turning off the set. Yes, we ran it 24-7 until a power loss occured. This time I'm not going to V sonic for the replacement ($ 150) , I will follow your advice and get it from Electronica with shipping for $82.25. Thank you for the information. PS. I will NEVER purchase another VIEW SONIC |
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loudi
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| Posted: Sat Jan 15, 2011 4:43 pm Post subject: Hannspree JT01-32E2-000G - Viewsonic N3252W |
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Some info on PSU repair.
These power supplies suffer from Dried up capacitors on the secondary side of the Power supply, When these go, Mainly the ones for the 5V (CS21,22 = 1500uF 16V and the smaller 220uF CS20) they cause the primary side to become unstable, Higher than normal peaks blow the Transistor Q7 (MMBT4401LT1G) this usualy goes short circuit Collector to Base this then results in a fairly high current blowing the Zenner ZD4, Although the MMBT4401 is rated at 600mA it is not the current that destroys it it is the higher than normal voltage. As this is used as a regulated 15V refrence ( NPN emmiter follower configuration) the junction temperature is exeeded when collector voltage increases, a typicay good set will only have 3V accross the collector/emmiter.
The best fix is to replace ALL the output caps with long life low ESR caps as the originals are rubbish and replace Q7 and ZD4.
Q7 can be any gen purpose NPN SOT 23 transistor that can handle more than 100mA
ZD4 is of the 400mW variety - the voltage is not so critical, I have found a 13V zenner to operate, but this will cause an elevated temperature in Q7.
The original caps CS21,22 are 10mm diameter 1500uF 16V, that frankly are not up to the job, I tend to replace with larger 12.5mm 105C panasonic long life 1000uF 25V versions, (the increased operating voltage tends the give the caps a slightly lower ESR) higher ESR caps just cause the caps to run hotter and shorten life expectancy! the larger caps do not fit perfectly and tend to lean a little to get them to fit.
In conclusing these are a worthwhile repair but generaly the PSU design is poor, It could do with a small fan for some forced air cooling around the Power board especialy on the secondary side as they do run real hot! |
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loudi
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| Posted: Sat Jan 15, 2011 5:02 pm Post subject: Hannspree LCD TV PSU JT01 |
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| joefair2 wrote: |
| Do you know what the specs are on Q7 ??? |
Q7 is MMBT4401LT1G NPN 600mA transistor, although a Switching Transistor it is used as a simple emmitter folower linear regulator! any sot 23 NPN with a rating above 100mA will do
ZD4 is a 15V zenner (400mW)
It is the caps on the 5V output drying up (open circuit) that causes large voltage spikes to Kill Q7 and ZD4 (CS20,21,22 for 5V always on PSU)
You will also find the rest of the capacitors dead! |
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Guest
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| Posted: Sat Jan 15, 2011 5:04 pm Post subject: Re: R58 |
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| jc00 wrote: |
| Hi Svale, any chances you could give me the numbers on R58? |
R58 = 5.1K 0805 - part of the linear regulator Q7 and Zd4 circuit |
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Guest
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| Posted: Sat Jan 15, 2011 5:50 pm Post subject: Re: Parts to replace |
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ZD4 is a 15 Volt 400mW Zenner
Q7 MMBT4401LT1 |
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skeggyman
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| Posted: Thu Jan 20, 2011 11:25 am Post subject: FSP212-3F01 Help |
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Hi there, does anyone have a FSP212-3F01 PSU lying about? i rly need to know which capacitors are on the following
CS19
CS20
CS28
mine have fried lol |
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