Hannspree M19W1 2 secs on Prob

[ceedy]

Not been here for a while since I Recapped an Old ProView 700P from all the ace info on here..
Its still going great guns as my spare ..
Actually having to use it at the moment as my 19 in Hanspree has just died on Xmas eve !and 2 weeks outside its warranty , a bummer.

Here 's a Piccy of the offender ...


[/IMG]

Done a limited recap of all the obvious bulgers around the Right angle heatsink , but its still got the 2 seconds on problem.
Seems a similar layout to a few common boards . But I've limited testing equipment now .. and the Makers have been decidedly unhelpful with a replacement ( they will only do a whole LCD repair @ some cost and not flog me a PSU ?.
Any clues where I go go with this fella , t' was such a nice monitor.

Happy Xmas & new year all

Chris

[sabre504]

Re: Hannspree M19W1 2 secs on Prob

Hi most on here would recommend that you replace all the caps except the largest one which rarely fail (but can sometimes)
As a lot of the caps may not bulge but will lose capacitance or go out of range on ESR

[retiredcaps]

Re: Hannspree M19W1 2 secs on Prob

Here 's a Piccy of the offender ...

Please do not post inline (slows things down) or offsite (lead to potential unwanted popups). Use the manage attachments instead.

Done a limited recap of all the obvious bulgers around the Right angle heatsink , but its still got the 2 seconds on problem.

That blue cap looks like a Radio Shack cap. Radio Shack does not sell low ESR caps that are required for a SMPS application.

See this for a list of recommended caps.

https://www.badcaps.net/forum/showthread.php?t=2280

For your 2 seconds to black, it could be

1) bad caps
2) bad inverter transformer
3) bad ccfl or wiring
4) something wrong in the sense circuitry

See this guide on how to troubleshoot starting with post #13

https://www.badcaps.net/forum/showthread.php?t=10419

[ceedy]

Re: Hannspree M19W1 2 secs on Prob

Happy New year all..

Done a recap.. all except the biggun.. and no change , switch off switch on
1-2 seconds ok then off.

One symptom I've just noticed during playing about is .. the Screen will switch on and off during a Boot up
so as the PC goes through the various startup screens it will go on then off .
is this due to the various Frequencies being used ? from the Old Dos'y up to the windows ( in my case 75 mhz) screen.
Would this indicate the probem is in the sensing circuitry just a guess?

Where can I go now ???

Chris

[retiredcaps]

Re: Hannspree M19W1 2 secs on Prob

Where can I go now ???

See my suggestions in post #3. You can rule out bad caps now and move down the list.

[ceedy]

Re: Hannspree M19W1 2 secs on Prob

Just a Pic of the Track side of the Board.. can just make out the IC's numbers and looked them up on the net .? ..

thanks for the reply will have a go at the other area ..

reckon I'll be back tho' ..

[Mr_Bodgit]

Re: Hannspree M19W1 2 secs on Prob

Happy New year all..

Done a recap.. all except the biggun.. and no change , switch off switch on
1-2 seconds ok then off.

One symptom I've just noticed during playing about is .. the Screen will switch on and off during a Boot up
so as the PC goes through the various startup screens it will go on then off .
is this due to the various Frequencies being used ? from the Old Dos'y up to the windows ( in my case 75 mhz) screen.
Would this indicate the probem is in the sensing circuitry just a guess?

Where can I go now ???

Chris

some monitors do turn off and on during booting up windows as things change (size and refresh rate adjustment) connect the monitor to the pc after loading windows up, dual output cards are handy for testing monitors on the second output.

does the power LED stay on after the screen goes black? does it go off compleatly or to standby?

if the power light stays on then i would connect the CCFL tubes from your working monitor to the inverter on the one thats faulty, no need for any other connections, just the tube wires and see what happens, if they stays on then its one of the CCFL's thats the problem and causing it to turn off, like wise to test the inverter, connecting the working screen ccfl's to it and see if it still turns off, if the connections are the same its the easiest test to do,

just sorted my first 2 faulty screens out by testing ccfl's after a few bulging caps dint sort 2 seconds black out, but they had been on for 45k hours

Regs
Rich

[ceedy]

Re: Hannspree M19W1 2 secs on Prob

some monitors do turn off and on during booting up windows as things change (size and refresh rate adjustment) connect the monitor to the pc after loading windows up, dual output cards are handy for testing monitors on the second output.

does the power LED stay on after the screen goes black? does it go off compleatly or to standby?

if the power light stays on then i would connect the CCFL tubes from your working monitor to the inverter on the one thats faulty, no need for any other connections, just the tube wires and see what happens, if they stays on then its one of the CCFL's thats the problem and causing it to turn off, like wise to test the inverter, connecting the working screen ccfl's to it and see if it still turns off, if the connections are the same its the easiest test to do,

just sorted my first 2 faulty screens out by testing ccfl's after a few bulging caps dint sort 2 seconds black out, but they had been on for 45k hours

Regs
Rich

Thanks I'll try that .. I've a CCFL Driver module board I bought on Fleabay
a while ago to try on another ( failed repair) LCD.
It only needs a 12 v supply to drive the Tubes. that should do ?.

I 'll dig it out tomorrow and have a go.

I can see the display with a torch ok . and the power light does stay on all the time during the blackouts, switch on and off and the picture is back for a moment .


I've just pulled the 3 transformers of the board, and a 4 Pin semiconductor but not quite sure which pins to test with my old Fluke 77.

Just taking some piccys of the offenders .

Chris

[ceedy]

Re: Hannspree M19W1 2 secs on Prob

Just powered up the tubes , all seem good .. used this module form fleabay..

also here's the transformers... and the one semiC i've pulled off .

C.

[ceedy]

Re: Hannspree M19W1 2 secs on Prob

Small transformer ..
4 pins 2 coils = 1 ohm each

7 Mohms between windings
----------------
The longer one SPI 8TC00293 8 pins,

across the 4 pairs of pins ( shortest width )?

resitances are :

1540 ohm 1.2ohm 1.2ohm 1127ohm


Open circuit between pins along the long sides


Not sure which pins to check on the First tranny. ?

or how to check the 4 pins semi ?

C.

[Rtech]

Re: Hannspree M19W1 2 secs on Prob

Your 8 pin one is faulty......1.2ohms are the primaries,and they are correct, the other two readings are the secondaries(driving the Backlights)and they shoud be within 5% of each other(some people like 3%), so it looks like the 1540 one is probably the faulty one,and you will need a new one ...IF YOU CAN FIND ONE !!!!!!!
Good hunting

[retiredcaps]

Re: Hannspree M19W1 2 secs on Prob

http://lcdparts.net/T.aspx might have them. They have 2 part numbers that are close

8TC00221 and 8TC00332

You can always give them a call or send them an email.

[ceedy]

Re: Hannspree M19W1 2 secs on Prob

Hi again

many thanks for the input .. Looking to be a tricky replacement.?

must ask ...tho' how would a tranny secondary mismatch cause the black out on all the tubes ?? just wondering about the sequences that would happen to cause it ?.

wouldn't it only give a differing output to the top & bottom tubes, as they feed direct to the tubes ??

Chris. ( Oldish and tryin to to retire! myself! )

[PlainBill]

Re: Hannspree M19W1 2 secs on Prob

Hi again

many thanks for the input .. Looking to be a tricky replacement.?

must ask ...tho' how would a tranny secondary mismatch cause the black out on all the tubes ?? just wondering about the sequences that would happen to cause it ?.

wouldn't it only give a differing output to the top & bottom tubes, as they feed direct to the tubes ??

Chris. ( Oldish and tryin to to retire! myself! )

You are exactly right in the effect, but miss the implications. An inverter is best thought of as a constant-current AC source with over voltage and over current protection.

The inverter controller monitors the total current through the CCFLS, and adjusts the drive signal to maintain the proper level. It also checks the voltage across every CCFL and will shut down if any exceeds the safe level. This is to detect a broken lamp or broken wire to a lamp. It also checks the current through each lamp and will shut down if the current through any lamp rises too high (lamp current rises as the tube ages).

Now consider the implications of a shorted secondary. The output voltage will be reduced because the total number of turns has been reduced. The output voltage will be further reduced because the shorted turns act as a shunt, loading the primary. Since the output voltage of the transformer is reduced, the current through the CCFL will be reduced. Since the inverter is trying to maintain a constant current through all CCFLs, it increases it's drive, and the good CCFL will be handling more current, and trip the over current protection.

PlainBill

[ceedy]

Re: Hannspree M19W1 2 secs on Prob

Many thanks . what a brilliant explanation.. just the thing to fill to large holes in my ole brain , ( not used as much these days ? LOL..)

As its looking tricky to source this lil fella .. is there much variation in specs
I can look for , especially as it needs to physically fit as well ?,
Not many adverts seem to give the dimensions , unless that is they are all the same size ??? .

thanks again Chris

----------------------------

You are exactly right in the effect, but miss the implications. An inverter is best thought of as a constant-current AC source with over voltage and over current protection.

The inverter controller monitors the total current through the CCFLS, and adjusts the drive signal to maintain the proper level. It also checks the voltage across every CCFL and will shut down if any exceeds the safe level. This is to detect a broken lamp or broken wire to a lamp. It also checks the current through each lamp and will shut down if the current through any lamp rises too high (lamp current rises as the tube ages).

Now consider the implications of a shorted secondary. The output voltage will be reduced because the total number of turns has been reduced. The output voltage will be further reduced because the shorted turns act as a shunt, loading the primary. Since the output voltage of the transformer is reduced, the current through the CCFL will be reduced. Since the inverter is trying to maintain a constant current through all CCFLs, it increases it's drive, and the good CCFL will be handling more current, and trip the over current protection.

PlainBill

[ceedy]

Re: Hannspree M19W1 2 secs on Prob

Found a lot of similar ( up to a point) Boards available complete with a very close layout and specs ..same part number but a slightly differin' shape board

like this ..

http://cgi.ebay.co.uk/Power-Board-FS...item3a610d9a16

I thinking maybe the best way to get a small pile of sparse to test/check/replace would be to get a whole board and swap the part ??
they are not too expensive ?? even if I have to wait from HK, can always test it before pulling to bits ..

seem reasonable idea ??

C.

[PlainBill]

Re: Hannspree M19W1 2 secs on Prob

Found a lot of similar ( up to a point) Boards available complete with a very close layout and specs ..same part number but a slightly differin' shape board

like this ..

http://cgi.ebay.co.uk/Power-Board-FS...item3a610d9a16

I thinking maybe the best way to get a small pile of sparse to test/check/replace would be to get a whole board and swap the part ??
they are not too expensive ?? even if I have to wait from HK, can always test it before pulling to bits ..

seem reasonable idea ??

C.

Depends on what type of personality you have.

One type will cheerfully strip the board for parts, discarding it when it has no useful parts left.

Another type will discard the board quickly because it's bad. Usually this occurs shortly before you need another part from the board.

A third type will be compelled to repair the donor board.

PlainBill

[ceedy]

Re: Hannspree M19W1 2 secs on Prob

Depends on what type of personality you have.

One type will cheerfully strip the board for parts, discarding it when it has no useful parts left.

Another type will discard the board quickly because it's bad. Usually this occurs shortly before you need another part from the board.

A third type will be compelled to repair the donor board.

PlainBill

So there's no major flaw in Plan A ?

1 & 3 apply to me !!

I'm a right old magpie!! I've boxes of odd bits I've stripped off injured stuff .. nothing to suit here tho '

Usually I need a part a week or so after i've chucked it in clearup .. :p.

I'll grab one of these in a last attempt ... Back in a week or so to report ??
of any success.
take care all

C.

[ceedy]

Re: Hannspree M19W1 2 secs on Prob

My New Donor PSU has turned up .( actually a UK supply)

The 8 pins trans measures right .. so will
start swapping with this.

Looks a nice close layout with near indentical components.
Cheap way to get the parts @ £12 delivered .

[ceedy]

Re: Hannspree M19W1 2 secs on Prob

Touch wood ( using head as its nearest).. it switches on and stays on ?. at least 5 mins at the mo...

Got a housefull of grandkids (only 2 but seem like more ) at the moment.
Not a good mix with open cases and lives lectric .. so will have to wait till they clear off later, to give it a good test.

heres hoping??

Chris