rainbow screen????

i-zombie

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ive been given a 1000 to try and fix for my mate,problem is that although it boots ok ive got a lovley flashing rainbow effect on screen-wtf is this

also ive tried to force an update and the damn thing has nit on the display and on screen it reels thru thousands ov numbers all variations of dh b50109b3

any ideas-please (i get 200 marlboro if i can sort it)
 

Spectre

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I've seen some weird on-screen effects caused by caps going short around the AV section of the board.
 

Teeny

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you could always try gong into the settings and making sure it's not set on RGB. It should be set on composite, the reason I say this is cos a friend of mine kept getting a pinky screen, when I checked the setting it was set on RGB, change it to composite and everythings fine now. I know this isn't excactly the same as rainbow effect, but worth a try mate.

Hope this helps
 

i-zombie

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thanks spectre i will have to look into that later,@tina thanks but ive already tried that

i left it updating last night and when i tried it earlier it came on ok but i soon had artifacts all over the place,then back into my flashing rainbow-alsoo it seems to take an age for the channels to come thru-like its gotta warm up first ---any ideas on this-i get the no t stream msg in eng menu but if i leave it a few hours it usualy come on
 

i-zombie

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no ive redone the cable with brand new cable-and ive tried other boxes on it,also spectre which is the av part ov the board?
 

Spectre

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Does the engineers menu screen suffer from the same problem?
 

i-zombie

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yep ive tried rf and yep engineers menu the same-ive now lost writing just got a rainbow
 

mentholflash01

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hi
sorry to but in but i have a 1000 that delivers green screen in eng menue it says av microcode failed to load but it boots up to 890 with no channels displayed and will do a forced update
thanks
 

Spectre

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My bet is on short circuit caps.

The AV part of the board is the area around the SCART sockets, lots of SMT caps to test!
 

Spectre

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mentholflash01 said:
hi mate do i just do continuety test on all caps in this section
thanks

Yes.

There is one on some boxes that appears short to some meters (it's accross the backup battery!) so be aware of that one or disconnect the battery by desoldering a lead.

I remember seeing one with the AV Microcode fault but don't remember if it was a S/C cap or not, was a while ago now.

Here's the approximate area to look for AV faults though:
 

mentholflash01

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hi mate`sorry to sound so stupid but once told itll stick
the only things that arent caps there are the 3 pin black things is this right most of all else are caps and need checking ther is a lot i was gonna`sudgest replaceing them1 by 1 but there is much too many
lol
thanks a lot mate for your help
 

Spectre

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They aren't all caps, there are some inductors which look similar and show as short circuit or low resistance.
 

Spectre

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mentholflash01 said:
sorry mate
how can i tell the difference
thanks again

Experience is probably the easiest way, test all components with your continuity tester and note the look of the types that always show S/C and ones that don't.

You should start to recognise what are caps or what's something else by their appearance after a bit practice.

Some caps appear as a short for a small ammount of time after connecting the tester also, they appear O/C after they have charged.
 
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