Home |
Search |
Today's Posts |
|
Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
|
|||
|
|||
Diamond Monitor 1997 (ACER 7279G) Help
I am attempting to fix this 19" monitor. I have found a schematic on a
Russian site :-) part of the eht section is scanned and viewable here http://users.tpg.com.au/users/verdons2/7279.htm Symptom: no EHT /green light on. I have disconnected the smps from main board and it runs ok. I have checked caps around Hor out and they look ok with regards to ESR. I can find no bad joints around the FBT or HOT drive Txfmr. I checked the FBT and it rings well, the 3000p cap on the eht lead measures ok. I pulled out the Q313 HOT BU2520DX and replaced it with a BU508D (had on hand) and also Q304 an IRF640 (was 634) and tried a 740 (on hand). Also I replaced the diode D305 and the 4 470p/2kV caps across the HOT's C-E. I got a picture for about 5 secs, there was a short blink and then back to nogo status When in this condition and I power on: the HORV signal from IC304 tda4855 driving this circuit appears for a few seconds then stops. There is a signal on the BU2520 base before HORV stops. I can see a switching signal on Q304's gate. 45V on HOT emitter There is a slight fizzing sound...perhaps heating of the FBT primary? Should I replace the HOT and Mosfet with the correct type and see what happens? Is there some other component I should check before I do this? Thanks in advance Russell (wish I had a variac!) |
#2
|
|||
|
|||
Diamond Monitor 1997 (ACER 7279G) Help
I must go by your description. I have not worked on the model you have. I
am sure, you need the correct HOT for sure. The flyback most likely has to also be replaced. I have seen this before, but not in the make of monitor you have. -- Greetings, Jerry Greenberg GLG Technologies GLG ========================================= WebPage http://www.zoom-one.com Electronics http://www.zoom-one.com/electron.htm ========================================= "Verdons" wrote in message ... I am attempting to fix this 19" monitor. I have found a schematic on a Russian site :-) part of the eht section is scanned and viewable here http://users.tpg.com.au/users/verdons2/7279.htm Symptom: no EHT /green light on. I have disconnected the smps from main board and it runs ok. I have checked caps around Hor out and they look ok with regards to ESR. I can find no bad joints around the FBT or HOT drive Txfmr. I checked the FBT and it rings well, the 3000p cap on the eht lead measures ok. I pulled out the Q313 HOT BU2520DX and replaced it with a BU508D (had on hand) and also Q304 an IRF640 (was 634) and tried a 740 (on hand). Also I replaced the diode D305 and the 4 470p/2kV caps across the HOT's C-E. I got a picture for about 5 secs, there was a short blink and then back to nogo status When in this condition and I power on: the HORV signal from IC304 tda4855 driving this circuit appears for a few seconds then stops. There is a signal on the BU2520 base before HORV stops. I can see a switching signal on Q304's gate. 45V on HOT emitter There is a slight fizzing sound...perhaps heating of the FBT primary? Should I replace the HOT and Mosfet with the correct type and see what happens? Is there some other component I should check before I do this? Thanks in advance Russell (wish I had a variac!) |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
2nd day of Metal working class...grinding cutting tools | Metalworking | |||
mapled out | Woodworking |