Zenith DLP Set Not Working After Lamp Replacement
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From: Chris F. on 6 Aug 2008 17:16 I posted a message about this a few weeks ago, regarding replacement of the blown lamp. After installing the new lamp, the set still won't start up; the "replace lamp" error light flashes instead. Checking the power input to the H.V. power supply (or lamp ballast I suppose), I measured a peak of over 300 VDC initially but it quickly drops to (and stays at) about 160. The 450 volt electrolytic cap connected across the power input suggests that the operating voltage should be much higher than 160. So what now? Is this a ballast problem or something on the main power supply? I can't afford to gamble any more money on this thing. The model and chassis numbers BTW are E44W46LCD and MB-042B respectively.
From: Franc Zabkar on 7 Aug 2008 01:32 On Wed, 6 Aug 2008 14:16:16 -0700, "Chris F." <zappyman(a)hotmail.com> put finger to keyboard and composed: > I posted a message about this a few weeks ago, regarding replacement of >the blown lamp. After installing the new lamp, the set still won't start up; >the "replace lamp" error light flashes instead. Checking the power input to >the H.V. power supply (or lamp ballast I suppose), I measured a peak of over >300 VDC initially but it quickly drops to (and stays at) about 160. The 450 >volt electrolytic cap connected across the power input suggests that the >operating voltage should be much higher than 160. > So what now? Is this a ballast problem or something on the main power >supply? I can't afford to gamble any more money on this thing. > The model and chassis numbers BTW are E44W46LCD and MB-042B respectively. FWIW, I have a service manual for an LG MB-042C chassis. The DC supply voltage for the ballast is 370 min, 390 typ, and 410 max. This is derived from directly across the main 220uF/450V bulk capacitor (C820). It is not regulated. The parts list includes ... 6913V00002C BALLAST, EUC100 P/11 PHILIPS 100W POWERPACK BALLAST FOR LCD 6912V00006C LAMP, HIGH PRESSURE MECURY UHP 100W 1.0 PH P22 PHILIPS 100V 1A RN48SZ40H - Franc Zabkar -- Please remove one 'i' from my address when replying by email.
From: Chris F. on 7 Aug 2008 14:32 So based on that info, I should suspect the power supply isn't supplying enough voltage to the ballast? "Franc Zabkar" <fzabkar(a)iinternode.on.net> wrote in message news:54vk94hpn36dfpbi60hubbm3at0s70v8rq(a)4ax.com... > On Wed, 6 Aug 2008 14:16:16 -0700, "Chris F." <zappyman(a)hotmail.com> > put finger to keyboard and composed: > >> I posted a message about this a few weeks ago, regarding replacement of >>the blown lamp. After installing the new lamp, the set still won't start >>up; >>the "replace lamp" error light flashes instead. Checking the power input >>to >>the H.V. power supply (or lamp ballast I suppose), I measured a peak of >>over >>300 VDC initially but it quickly drops to (and stays at) about 160. The >>450 >>volt electrolytic cap connected across the power input suggests that the >>operating voltage should be much higher than 160. >> So what now? Is this a ballast problem or something on the main power >>supply? I can't afford to gamble any more money on this thing. >> The model and chassis numbers BTW are E44W46LCD and MB-042B >> respectively. > > FWIW, I have a service manual for an LG MB-042C chassis. > > The DC supply voltage for the ballast is 370 min, 390 typ, and 410 > max. This is derived from directly across the main 220uF/450V bulk > capacitor (C820). It is not regulated. > > The parts list includes ... > > 6913V00002C BALLAST, EUC100 P/11 PHILIPS 100W POWERPACK BALLAST FOR > LCD > > 6912V00006C LAMP, HIGH PRESSURE MECURY UHP 100W 1.0 PH P22 PHILIPS > 100V 1A RN48SZ40H > > - Franc Zabkar > -- > Please remove one 'i' from my address when replying by email.
From: Franc Zabkar on 7 Aug 2008 16:17 On Thu, 7 Aug 2008 11:32:33 -0700, "Chris F." <zappyman(a)hotmail.com> put finger to keyboard and composed: >So based on that info, I should suspect the power supply isn't supplying >enough voltage to the ballast? I don't know. If the ballast is drawing too much current, then I suppose it's possible for the DC supply to sag significantly. BTW, when I wrote that the 400V supply is not regulated, I should have said that this supply is derived from the rectified mains and passes through an active PFC circuit. Maybe you could insert a 1 ohm 10W series resistor into the DC feed to your ballast and measure the voltage drop across it. That would tell you the current draw. >"Franc Zabkar" <fzabkar(a)iinternode.on.net> wrote in message >news:54vk94hpn36dfpbi60hubbm3at0s70v8rq(a)4ax.com... >> On Wed, 6 Aug 2008 14:16:16 -0700, "Chris F." <zappyman(a)hotmail.com> >> put finger to keyboard and composed: >> >>> I posted a message about this a few weeks ago, regarding replacement of >>>the blown lamp. After installing the new lamp, the set still won't start >>>up; >>>the "replace lamp" error light flashes instead. Checking the power input >>>to >>>the H.V. power supply (or lamp ballast I suppose), I measured a peak of >>>over >>>300 VDC initially but it quickly drops to (and stays at) about 160. The >>>450 >>>volt electrolytic cap connected across the power input suggests that the >>>operating voltage should be much higher than 160. >>> So what now? Is this a ballast problem or something on the main power >>>supply? I can't afford to gamble any more money on this thing. >>> The model and chassis numbers BTW are E44W46LCD and MB-042B >>> respectively. >> >> FWIW, I have a service manual for an LG MB-042C chassis. >> >> The DC supply voltage for the ballast is 370 min, 390 typ, and 410 >> max. This is derived from directly across the main 220uF/450V bulk >> capacitor (C820). It is not regulated. >> >> The parts list includes ... >> >> 6913V00002C BALLAST, EUC100 P/11 PHILIPS 100W POWERPACK BALLAST FOR >> LCD >> >> 6912V00006C LAMP, HIGH PRESSURE MECURY UHP 100W 1.0 PH P22 PHILIPS >> 100V 1A RN48SZ40H - Franc Zabkar -- Please remove one 'i' from my address when replying by email.
From: Chris F. on 7 Aug 2008 22:57
What I did so far was just disconnect the lamp ballast. The voltage across C820 is still only 160V, and I also determined that all voltages derived from the switching supply (16, 32, etc) are proportionally low - the 16V supply is only measuring 6V, for example. I don't know too much about PFC circuits but I assume something has to take place to get the correct 400V across that cap, something which clearly isn't happening at this point. If you could Email me the schematic of that power supply I'd really appreciate it. I've got almost $150 in this thing now and giving up just isn't an option right now. "Franc Zabkar" <fzabkar(a)iinternode.on.net> wrote in message news:ovlm9418c3dfklcuid4fv6svhgk81vnqk4(a)4ax.com... > On Thu, 7 Aug 2008 11:32:33 -0700, "Chris F." <zappyman(a)hotmail.com> > put finger to keyboard and composed: > >>So based on that info, I should suspect the power supply isn't supplying >>enough voltage to the ballast? > > I don't know. If the ballast is drawing too much current, then I > suppose it's possible for the DC supply to sag significantly. BTW, > when I wrote that the 400V supply is not regulated, I should have said > that this supply is derived from the rectified mains and passes > through an active PFC circuit. > > Maybe you could insert a 1 ohm 10W series resistor into the DC feed to > your ballast and measure the voltage drop across it. That would tell > you the current draw. > >>"Franc Zabkar" <fzabkar(a)iinternode.on.net> wrote in message >>news:54vk94hpn36dfpbi60hubbm3at0s70v8rq(a)4ax.com... >>> On Wed, 6 Aug 2008 14:16:16 -0700, "Chris F." <zappyman(a)hotmail.com> >>> put finger to keyboard and composed: >>> >>>> I posted a message about this a few weeks ago, regarding replacement >>>> of >>>>the blown lamp. After installing the new lamp, the set still won't start >>>>up; >>>>the "replace lamp" error light flashes instead. Checking the power input >>>>to >>>>the H.V. power supply (or lamp ballast I suppose), I measured a peak of >>>>over >>>>300 VDC initially but it quickly drops to (and stays at) about 160. The >>>>450 >>>>volt electrolytic cap connected across the power input suggests that the >>>>operating voltage should be much higher than 160. >>>> So what now? Is this a ballast problem or something on the main power >>>>supply? I can't afford to gamble any more money on this thing. >>>> The model and chassis numbers BTW are E44W46LCD and MB-042B >>>> respectively. >>> >>> FWIW, I have a service manual for an LG MB-042C chassis. >>> >>> The DC supply voltage for the ballast is 370 min, 390 typ, and 410 >>> max. This is derived from directly across the main 220uF/450V bulk >>> capacitor (C820). It is not regulated. >>> >>> The parts list includes ... >>> >>> 6913V00002C BALLAST, EUC100 P/11 PHILIPS 100W POWERPACK BALLAST FOR >>> LCD >>> >>> 6912V00006C LAMP, HIGH PRESSURE MECURY UHP 100W 1.0 PH P22 PHILIPS >>> 100V 1A RN48SZ40H > > - Franc Zabkar > -- > Please remove one 'i' from my address when replying by email. |