grundig guvcd2800(ak49)dead


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grundig guvcd2800(ak49)dead

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ernie
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May 27, 2007, 8:04 AM

Post #1 of 14 (2064 views)
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grundig guvcd2800(ak49)dead	Can't Post

i have two of these tvs with freeveiw built in one is dead no st/by light the other one had a blown fuse and several componants in the power supply blown i repaired the power supply and now this one has the same fault as the other one i.e dead no st/by can these faults be in the freeview box as i cant find no faults on the main board.any advice appreciated

techchris
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May 27, 2007, 8:59 AM

Post #2 of 14 (2060 views)
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Re: [ernie] grundig guvcd2800(ak49)dead [In reply to]	Can't Post

this is from the toshiba website they use the same vestel chassis as yours i think.hope it helps.I dont know if the freeview section can be disconnected.also have you tried the eeprom which was a common failure on these tv's?
Chris

IC800 Switch mode power supply IC has failed. Sometimes failure of this IC can result in a number of other components being damaged. The components likely to have been damaged are shown highlighted on the schematic below.
Cure
Check and or replace the following parts:

Diode D892, D893 part no V30001318
Diode D891 part no V30007758
Transistor Q801 part no V30001386
Fuse F801 part no V20000848
Resistor R805,R852 part no V30000650
Resistor R806 part no V30000982
Resistor R855 part no V30000459
IC800 & R801 part no V30011968

ernie
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May 27, 2007, 9:25 AM

Post #3 of 14 (2058 views)
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Re: [techchris] grundig guvcd2800(ak49)dead [In reply to]	Can't Post

thanks for the advice chris.all them componants seem to be ok but i havent tried the eeprom yet so i will change that and get back to you.

ernie
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Jun 21, 2007, 12:22 AM

Post #4 of 14 (2040 views)
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Re: [techchris] grundig guvcd2800(ak49)dead [In reply to]	Can't Post

i changed the eeprom on these tvs but still the same you hear the power supply come on when first plugged in but thats it no st/by light or anything i wondered if it maybe the loptx as my meter shows them reading between good and bad.i have another question,i have some 32inch panosonic tvs with phillips tubes gone i was told to cut the print on the crt panel where the two heater wires are and to wrap a peice of wire round the loptx about 1and a half times have you heard of this before and if so is it a long lasting fix gratefull for any advice

rrobor
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Jun 21, 2007, 2:08 AM

Post #5 of 14 (2038 views)
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Re: [ernie] grundig guvcd2800(ak49)dead [In reply to]	Can't Post

What you are describing is a fix for a cathode heater short, if that is your issue it just means that the heater floats at the same potential as the cathode so there is no short. It will last as long as the tube will last, I have an abandoned Sony working in a relations house for 6 years now which has never failed. 2 points I will make is the wire is wrapped around the ferrite former of the transformer and locked there as far away from the overwind as you can, the wire should be well insulated, I use focus lead for it, 2 winds is OK, I have stepped this up on a flat tube to 3 winds as a last resort, that though will age the tube faster.

ernie
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Jun 21, 2007, 10:08 AM

Post #6 of 14 (2033 views)
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Re: [rrobor] grundig guvcd2800(ak49)dead [In reply to]	Can't Post

thanks for the info and the point you made about where to wrap the wire is usefull as i was just told to put it round the loptx.i am not sure if the two tvs i have are shorting from the cathode heater though as one goes red before cutting of and the other goes green then cuts of.but on the basis that they are scrap as they are anythings worth trying.i did try turning the tubes upside down but they still did the same.

rrobor
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Jun 21, 2007, 11:08 AM

Post #7 of 14 (2031 views)
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Re: [ernie] grundig guvcd2800(ak49)dead [In reply to]	Can't Post

Yes that sounds good to me for a cathode heater short. I have a mains to 6v transformer which I use before I muck around too much, its near enough to do the job and saves time if you are wrong. The earth pin is usually a bitch but the other usually has a resistor or chpke you can lift.

ernie
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Aug 11, 2007, 12:17 PM

Post #8 of 14 (2006 views)
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Re: [rrobor] grundig guvcd2800(ak49)dead [In reply to]	Can't Post

just mamaged to drag this panasonic out and trying to sort out which wires to disconnect.there are four wires going to the crt one goes to the heater and can be disconnected via a resister as you said but which is the other wire you disconnect.is it the one from the same plug that goes to earth and do you leave the other two wires connected.where the wire goes to the crt plug only one is marked with h that is the one via the resister so that one is sorted which leaves me three more wires one of them three is earth.could you advice me on this i would be very gratefull

rrobor
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Aug 12, 2007, 7:52 AM

Post #9 of 14 (2002 views)
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Re: [ernie] grundig guvcd2800(ak49)dead [In reply to]	Can't Post

You have to cut the print to isolate it from earth, do a neat V cut around the earth pin and you have a spark gap and isolation, how good is that.

ernie
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Aug 12, 2007, 11:28 AM

Post #10 of 14 (1999 views)
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Re: [rrobor] grundig guvcd2800(ak49)dead [In reply to]	Can't Post

thanks for that info.now i took the resister out to isolate the heater cut a v round the earth pin to isolate it put two winds of wire round the ferrite part of the loptx put the tv on and i get the static but the tube dont light up have i missed something out or done something wrong your advice is appreceated

rrobor
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Aug 13, 2007, 8:32 AM

Post #11 of 14 (1994 views)
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Re: [ernie] grundig guvcd2800(ak49)dead [In reply to]	Can't Post

unhook one wire and read what you have as resistance as a heater in the tube and get back.

ernie
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Aug 13, 2007, 9:37 AM

Post #12 of 14 (1992 views)
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Re: [rrobor] grundig guvcd2800(ak49)dead [In reply to]	Can't Post

sorry but i dont understand the bit about unhook one wire as the wire i put round the loptx isnt joined anywhere,just wound round twice and tied together.also to measure the heater resistance would it be the heater pin to earth if so i have 3.9ohms thanks for your advice

rrobor
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Aug 13, 2007, 12:50 PM

Post #13 of 14 (1989 views)
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Re: [ernie] grundig guvcd2800(ak49)dead [In reply to]	Can't Post

Now how do you expect that to work. The wire wrapped arount the flyback limb is part of a transformer, it has 6.3V flowing in it. One end is soldered on to the heater pin pad, the other end is soldered on to the bit you liberated from the earth wires. the winding must keep it away from the main body of the transformer and should be fairly heavy well insulated wire tighten it to the limb or glue it down so it remains in place.

ernie
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Aug 14, 2007, 12:17 AM

Post #14 of 14 (1984 views)
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Re: [rrobor] grundig guvcd2800(ak49)dead [In reply to]	Can't Post

thanks for your help on this fix.i must admit i wondered where the heater would get its power from when my mate told me about this fix in the first place as he never said anything about joining the wire to the crt but now you have pointed that out i am glad to say the tv is now working ok.i am very gratefull for your help and thanks again

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