Plasma Tv 42" Hot point No picture no sound

[ryann2k1]

I have a 42" plasma tv brand Hotpoint (it seems the boards are samsung made). When plugging the power source, tv turns on with green light turns on, but no picture and sound. A few second later, it indicator turns to red(stand by mode). After turning on with remote, tv indicator turn to green but still no picture and sound at all. There is one green light on the logic board (i think) which keeps blinking (see attachment). I have tried to unplug the X-board and Y-board( one at a time and all simultaneously) but the problem remains. I have measured Va, Ve, Vset, Vs, all are in normal rating voltage as shown in the specification attached on the back of the panel. Only Vscan which is supposed to be -182v, and the measure one is only -50v. i think this it the problem but i don't know how to further diagnose as i don't have the schematic diagram. Any help would be great. Thanks

[Hamie]

Re: Plasma Tv 42" Hot point No picture no sound

Unplug the buffers from the y-sus and check the vsc voltages again.

[ryann2k1]

Re: Plasma Tv 42" Hot point No picture no sound

I have done that, I unplug y-sus and measured, vsc measured at 0v (no voltage), Va,Ve and others are in normal range. I forgot to mention that I have replaced one capacitor at power supply unit, 47uF/50v. I thought that was the problem as the capacitor looks already bulging, but I was wrong, the problem still remains..

[Hamie]

Re: Plasma Tv 42" Hot point No picture no sound

The vsc voltage might only appear for a few seconds then drop to 0.
You'll need to quickly measure it as soon as the TV is plugged in.

[ryann2k1]

Re: Plasma Tv 42" Hot point No picture no sound

The vsc voltage might only appear for a few seconds then drop to 0.
You'll need to quickly measure it as soon as the TV is plugged in.

Thanks I will do that this weekend.

[Alastair E]

Re: Plasma Tv 42" Hot point No picture no sound

Unlike later sets this one has the -Vy, VSC, VSCAN,, VE etc generated on the PSU board, along with the Va and Vs supplies.

Some of these supplies are derived from the Vs supply but on the PSU, so any issues with the Vs supply, the PFC etc will give none of the other rails....

A common fault (It appears) is the PFC and Vs Controller chip can fail--which apparently is rarer than hens-teeth--uses same chip for both jobs--Bit weird.....

Unless its just for experience--I wouldn't waste any time on this 480i EDTV set, that has no HDMI or DTV....
--I'm sure it will be great on the spin-cycle though! (Hotpoint make washers here in UK, never any TV's etc....)

[tw2005]

Re: Plasma Tv 42" Hot point No picture no sound

Unlike later sets this one has the -Vy, VSC, VSCAN,, VE etc generated on the PSU board, along with the Va and Vs supplies.

Some of these supplies are derived from the Vs supply but on the PSU, so any issues with the Vs supply, the PFC etc will give none of the other rails....

A common fault (It appears) is the PFC and Vs Controller chip can fail--which apparently is rarer than hens-teeth--uses same chip for both jobs--Bit weird.....

Unless its just for experience--I wouldn't waste any time on this 480i EDTV set, that has no HDMI or DTV....
--I'm sure it will be great on the spin-cycle though! (Hotpoint make washers here in UK, never any TV's etc....)

Off topic , but Hotpoint for my memory in the 70's produced pretty good frypans, grillers etc. been gone for a very long time as a brand so probably someone purchased the rights to use it as a rebadge. all speculation of course but there's plenty of badges wacked on chinese TVs, thorn, PYE, AWA, are some others that come to mind. Sanyo was a rebadge for TVs too.

[Alastair E]

Re: Plasma Tv 42" Hot point No picture no sound

I Think Hotpoint was bought by someone like Beko I know Kenwood was amongst others...
Most TV sets here (Inc Panasonic) are going rebadged VESTEL Vomit, JVC, Sanyo, Alba, Technika, Bush, Baird, Xenius etc --All Vestel Crap!

Only four or five 'main' makers now--Vestel, Sony, LG, Samsung, Philips--rest will be rebadged or cheap Chinese rubbish with whatever name--or in some cases, NO name on at all--and NO clue who made 'em!

[ryann2k1]

Re: Plasma Tv 42" Hot point No picture no sound

the voltage for Vscan is 0-no voltage ( y sus is unplugged). My question is that does the Vscan voltage only appears once in closed loop, unlike Ve, Va, and others?

[ryann2k1]

Re: Plasma Tv 42" Hot point No picture no sound

The vsc voltage might only appear for a few seconds then drop to 0.
You'll need to quickly measure it as soon as the TV is plugged in.

the voltage for Vscan is measured from -50 (supposed to be lower than -100v) than gradually decreased to 0 v( y sus is unplugged). My other question is that does the Vscan voltage only appears once in closed loop, unlike Ve, Va, and others?

[ryann2k1]

Re: Plasma Tv 42" Hot point No picture no sound

anyone can help?

[Alastair E]

Re: Plasma Tv 42" Hot point No picture no sound

VScan is derived from either Vs or Va on that chassis--cant remember which--But Isnt closed loop as I recall....

IF however--There's a fault on Y, then this could be picked up by the control-system/Fault det, that then shuts down the PSU, but not as in closed-loop regulation etc--Unplugging PSU may actually Cause the observed results on an otherwise normal set...
--This tends to shut most of the PSU down though....

Is Va and Vs present and correct while on?--IF these are wrong/not present then Vscan wont be right anyway, as it is derived from one or the other ...

[ryann2k1]

Re: Plasma Tv 42" Hot point No picture no sound

VScan is derived from either Vs or Va on that chassis--cant remember which--But Isnt closed loop as I recall....

IF however--There's a fault on Y, then this could be picked up by the control-system/Fault det, that then shuts down the PSU, but not as in closed-loop regulation etc--Unplugging PSU may actually Cause the observed results on an otherwise normal set...
--This tends to shut most of the PSU down though....

Is Va and Vs present and correct while on?--IF these are wrong/not present then Vscan wont be right anyway, as it is derived from one or the other ...

Thank you for responding. Vs and Va are in normal range. I am still wondering, if vscan is not close loop...the measured voltage is supposed to be the same, when unplugging the Y sustain and when plugged. When i plug, Vscan around less than -50v but when i unplugged, Vscan = 0v.

[ryann2k1]

Re: Plasma Tv 42" Hot point No picture no sound

is there any way to get an example of circuit diagram for the "similar" power supply board and Y sustain board?

[ryann2k1]

Re: Plasma Tv 42" Hot point No picture no sound

is there any way to get an example of circuit diagram for the "similar" power supply board and Y sustain board?

Please any one can respond?