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Epson EMP-7600 Projector

D

dodger741

Jan 1, 1970
0
A projector I bought used for my son seems to work fine for about 40
minutes then the "lamp indicator" blinks red and the projector lamp
turns off. User manual says replace bulb because it has reached its
end of life. The hours indicated 611 hours which I reset with no
change in operation. I replaced the bulb with a new one and the same
thing happens. From what I have read (wikipedia) the life of the bulb
has to do with the voltage required to drive it. It becomes higher as
life goes on. I can imagine some sort of circuit to sense either
voltage or current on the powersupply module and inform the processor
when some limit is reached. The bulb type is ELPLP12. Does anyone have
any information on this or any schematic documentation which might
help me troubleshoot it. I do have experience with high voltage
supplies etc.
 
J

Jerry G.

Jan 1, 1970
0
There may be problems in the power supply or with the cooling of the
system. The service people would change the power supply to start, and
take internal temperature readings.

Most of the manufactures of these units will not sell spare parts, or
any service manuals to end users. To service this unit is specialized
work.

Research for the service rep in your area. Take the unit in for an
estimate. It is possible that the repair may be worth the cost.


Jerry G.
======
 
J

James Sweet

Jan 1, 1970
0
dodger741 said:
A projector I bought used for my son seems to work fine for about 40
minutes then the "lamp indicator" blinks red and the projector lamp
turns off. User manual says replace bulb because it has reached its
end of life. The hours indicated 611 hours which I reset with no
change in operation. I replaced the bulb with a new one and the same
thing happens. From what I have read (wikipedia) the life of the bulb
has to do with the voltage required to drive it. It becomes higher as
life goes on. I can imagine some sort of circuit to sense either
voltage or current on the powersupply module and inform the processor
when some limit is reached. The bulb type is ELPLP12. Does anyone have
any information on this or any schematic documentation which might
help me troubleshoot it. I do have experience with high voltage
supplies etc.


I would start by checking electrolytic capacitors on the lamp ballast, and
in the power supply for the whole unit. If you reset the bulb timer and it
still shuts down, then something is wrong with it.
 
D

dodger741

Jan 1, 1970
0
I would start by checking electrolytic capacitors on the lamp ballast, and
in the power supply for the whole unit. If you reset the bulb timer and it
still shuts down, then something is wrong with it.

Well I took it apart and found several things. First of all a lot of
tightly packed boards etc - what a nightmare to work on. The ballast
board is very compact with transformers and igniter module, and 2
daughter boards soldered in. I found the current sensing resisters on
the board (10ea 1.0ohm resisters in parallel) and will measure the
current shortly. I found a similiar manual online (EMP 7700) which had
block diagrams and some details about the power supply. They talked
about a 28 pin connector which carries the supply voltages to the main
board. I have a 28 pin connector and all my supply voltages matched
this manual except pin 14 which is listed as 12 volts and I measure 0
(not even a hint of voltage even looking with a scope). There is a
wire in the connector so it is for something. The other item was a
small fan (2.5") which blows on the low voltage board and also the HV
ballast board. The fan doesn't come on. It is a 12 volt fan which is
connected to the LV supply board. The voltage supplied at the
connector is 8 volts with no ripple. I plugged the fan into 12 volts
and it doesn't work. I thought this might be it so I rigged up
another fan to blow on the boards and plugged the unit in. The light
came on but went out in half the time it used to (25min). I am just
turning the unit on (blue screen) with no inputs). Maybe with the
case off etc the air flow is not working correctly which caused this
failure. Seems like I need to disassemble the whole thing to get to
the LV supply board to investigate the 8v fan drive for the 12v fan.
Any more thoughts??
 
J

James Sweet

Jan 1, 1970
0
dodger741 said:
Well I took it apart and found several things. First of all a lot of
tightly packed boards etc - what a nightmare to work on. The ballast
board is very compact with transformers and igniter module, and 2
daughter boards soldered in. I found the current sensing resisters on
the board (10ea 1.0ohm resisters in parallel) and will measure the
current shortly. I found a similiar manual online (EMP 7700) which had
block diagrams and some details about the power supply. They talked
about a 28 pin connector which carries the supply voltages to the main
board. I have a 28 pin connector and all my supply voltages matched
this manual except pin 14 which is listed as 12 volts and I measure 0
(not even a hint of voltage even looking with a scope). There is a
wire in the connector so it is for something. The other item was a
small fan (2.5") which blows on the low voltage board and also the HV
ballast board. The fan doesn't come on. It is a 12 volt fan which is
connected to the LV supply board. The voltage supplied at the
connector is 8 volts with no ripple. I plugged the fan into 12 volts
and it doesn't work. I thought this might be it so I rigged up
another fan to blow on the boards and plugged the unit in. The light
came on but went out in half the time it used to (25min). I am just
turning the unit on (blue screen) with no inputs). Maybe with the
case off etc the air flow is not working correctly which caused this
failure. Seems like I need to disassemble the whole thing to get to
the LV supply board to investigate the 8v fan drive for the 12v fan.
Any more thoughts??

The 8V to the fan may be by design, to run it at a slower quieter speed. If
the fan is bad, fix/replace it first. The circuit may detect the current
draw or RPM of the fan, is it a 3 wire type with a tach signal?
 
D

dodger741

Jan 1, 1970
0
Just a follow-up. There are several other fans in this unit. I had
suspected a thermistor on the lamp as the culprit but as I tested I
found that when this over-temp condition is triggered, a different
failure mode occurs. Also the fans speed up so I suspect the 8v is a
variable voltage/speed fan as James suggested. The other thing I
discovered is that it does make a diffference if you don't have a
changing presentation on the screen as it does turn-off after a while
with no changing input. In the end, I replaced the fan and it seems
to be working correctly now. Thanks to all who commented and made
suggestions.
 
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