Spectroniq PLTV-3250 wont start

[ratdude747]

Re: Spectroniq PLTV-3250 wont start

replace all caps. even ones that look fine are suspect. they fail without visual signs.

[Test540va]

Re: Spectroniq PLTV-3250 wont start

OK... I took the "Power Supply" outta my Protron PLTV-3250. I am going to attempt to replace the Capacitors that are bulged. (I only see two bulged capacitors) ... My question is when I removed the Power Supply, there are "two sockets right next to each other labeled CNS-4 and CNS-3.... Wich One do I plug the White Pluggy Thing back into ? I forgot

[diggah]

Re: Spectroniq PLTV-3250 wont start

Thanks for the link Toasty,

I too am the proud owner of a dead proscan pltv-3250; and have had no luck replacing the suspect caps. The only other place I knew that had the part wanted twice as much, and I was riding the fence since I really don't know what else might be wrong with the set.

You may have freed up a little more space in our local landfill.

[glen65]

Re: Spectroniq PLTV-3250 wont start

Hello Glen,
A question for you if I may,
You emphasise the use of anaIog meter,

( I was able to track down the fault doing comparison reading using an analog meter. )

As a hobbyist, am I to take it that the DMM would not have done this, and if so can you explain to me why, please, thanks,
bob

It probably would have been fine to use my DMM for the comparison resistance checks, I did it mostly out of personal preference and to get a second opinion.

[Bobdee]

Re: Spectroniq PLTV-3250 wont start

Hello Glen,
A question for you if I may,
You emphasise the use of anaIog meter,

( I was able to track down the fault doing comparison reading using an analog meter. )

As a hobbyist, am I to take it that the DMM would not have done this, and if so can you explain to me why, please, thanks,
bob

[glen65]

Re: Spectroniq PLTV-3250 wont start

That was one of your original questions.
Congratulations of your now working TV. You had invested on the new supply to find out but for that price you wouldn't find a TV that price with a backup power supply (that maybe can be used for other purposes in the meantime ...).

I checked all over the place for service info for
that set and came up empty. So there really wasn't much choice
but to get a new supply. It also didn't help that I was misled
into believing that one of the diodes was good. Thats what
was killing the 5 volt standby to begin with. Normally there's no problem
testing diodes in circuit buy simply using the diode test on
my DMM. However the amount of leakage on this one was
small enough to throw the reading off, giving it the appearance that
it was ok. I was able to track down the fault doing comparison reading using an analog meter.

[EGuevarae]

Re: Spectroniq PLTV-3250 wont start

Update:
To turn the supply on you need to inject 3.3 volts at the terminal
marked o/f on the socket where the 5 volt line is at.
I imaging if one wanted to start it at the bench it
it could be done by simply tapping off of the 5 volt standby line,
with something to reduce the voltage.

That was one of your original questions.
Congratulations of your now working TV. You had invested on the new supply to find out but for that price you wouldn't find a TV that price with a backup power supply (that maybe can be used for other purposes in the meantime ...).

[glen65]

Re: Spectroniq PLTV-3250 wont start

Update:

Ok the new supply came in, I connected it to the monitor
and all works fine. However I still wanted to repair the old one.
So I took both supplies to the bench and connected a source to them
in order to do some comparison testing to find out why I wasn't getting
the 5 volt standby voltage. I check for voltage on the new supply
in the area where I had to replace a surface mount transistor (Q7) on the
old supply, it measured just under 15 volts. I checked the same areas
on the old supply and the reading was about 1.5 volts. I went to diode
test and rechecked the transistors and diodes in that area of the board,
and all looked ok. Next I decided to do some comparison resistance checks,
for this I decided to beak out my Simpson analog meter. I noticed that
the resistance between two of the terminals on Q7 was lower than
compared to the new supply.

I started desoldering one leg of some
of the components to find out which one was abnormally lowering the
resistance of the circuit. I eventually made it to a surface mount
15 volt zener diode. Once disconnected the resistance of the
circuit went back to normal to match what I was getting from
the new supply. I checked the diode out of circuit with my
analog meter and sure enough that's what was throwing the
resistance off. The diode was neither shorted nor open and
had originally checked ok using diode check on a digital meter
when in circuit. I replaced the diode then put the supply back
into the monitor and it checked ok.

To turn the supply on you need to inject 3.3 volts at the terminal
marked o/f on the socket where the 5 volt line is at.
I imaging if one wanted to start it at the bench it
it could be done by simply tapping off of the 5 volt standby line,
with something to reduce the voltage.

[EGuevarae]

Re: Spectroniq PLTV-3250 wont start

Didjagetit?didjagetit?didjagetit?didjagetit?didjagetit?didjagetit?didjagetit?

Didjafixit?didjafixit?didjafixit?didjafixit?didjafixit?didjafixit?didjafixit?didjafixit?






The 6 year old in the back seat,
Toast

Make him sign up with his own name and post under it, or else your reputation will suffer with postings like that ..

[Toasty]

Re: Spectroniq PLTV-3250 wont start

Didjagetit?didjagetit?didjagetit?didjagetit?didjagetit?didjagetit?didjagetit?

Didjafixit?didjafixit?didjafixit?didjafixit?didjafixit?didjafixit?didjafixit?didjafixit?






The 6 year old in the back seat,
Toast

[glen65]

Re: Spectroniq PLTV-3250 wont start

Excellent. Glad to see this resolved. Now you have another rainy day project.

I'll call it resolved when I actually see the monitor running properly.

Please post back when you get the original repaired. It interests me to see what exactly failed.

You bet

What about the IC's on the underside? Are they "standard issue" or proprietary?

They are standard issue. I found a shorted transistor in very close
proximity of one of them. It may have damaged the IC.

What does the SMT you replaced control further along in the circuit?

Not really sure, I think it may be controlled by the adjacent IC.
There's where a schematic would have been useful.

You said it was shorted, so what caused that? Is one of the regulator transistors or MOSFET's also blown perhaps? Open or shorted?

I checked all other transistors, diodes, and resistors and all checked
ok. I suppose its possible that the caps I had to replace were responsible.
Some were literally bulging out at the top.


Later

[Toasty]

Re: Spectroniq PLTV-3250 wont start

Excellent. Glad to see this resolved. Now you have another rainy day project.

Please post back when you get the original repaired. It interests me to see what exactly failed.

About the only thing that would keep this unit from getting repaired is maybe the inductors.
They are most likely custom made and cannot be ordered as a replacement.

What about the IC's on the underside? Are they "standard issue" or proprietary?

What does the SMT you replaced control further along in the circuit?

You said it was shorted, so what caused that?

Is one of the regulator transistors or MOSFET's also blown perhaps? Open or shorted?

Cheers!
Toast

[glen65]

Re: Spectroniq PLTV-3250 wont start

Save yourself the continuing headache:

Ebay FSP194-3F01 Only 4 left - Hurry!

For $69 you're up and running.

I ordered one directly from their website rather than Ebay which
saved me a few bucks on the shipping.

Then you can perhaps use that one to figure out the busted one.

About the only thing that would keep this unit from getting
repaired is maybe the inductors. They are most likely custom
made and cannot be ordered as a replacement.

If you go that way and are gonna trash the dead unit, I'd be interested in taking a poke at it. LMK

The only reason I am replacing it is because of the time element.
I will repair it and then use it is as a test supply.

FYI: FSP replied to my inquiry and their policy does not allow them to supply schematics.

Toast

That's certainly nothing new, there are a number of companies that
have a similar policy. Some wont give you data unless you are a
warranty authorized service center.

[Toasty]

Re: Spectroniq PLTV-3250 wont start

Save yourself the continuing headache:

Ebay FSP194-3F01 Only 4 left - Hurry!

For $69 you're up and running.

Then you can perhaps use that one to figure out the busted one.

If you go that way and are gonna trash the dead unit, I'd be interested in taking a poke at it. LMK

FYI: FSP replied to my inquiry and their policy does not allow them to supply schematics.

Toast

[glen65]

Re: Spectroniq PLTV-3250 wont start

Don't know. You didn't answer my questions.
Read the paragraph again that starts with "Now, regarding the way..."

Did you try to contact FSP support for a schematic or a replacement?

So far they will not contact me back.

For safety's sake, I do hope you are testing this with an isolation transformer.

Yes

Please remember that this circuit is live to the house current.
Getting yourself across any point to ground could be deadly.[/B]

Yep,
I simply use the same high level of caution that I use when working around
the 4000 volt high voltage section of Microwave ovens.

[EGuevarae]

Re: Spectroniq PLTV-3250 wont start

Current limiter.

OK. Thanks for the Technical term.
Learning something new every day.

[PCBONEZ]

Re: Spectroniq PLTV-3250 wont start

Current limiter.

[EGuevarae]

Re: Spectroniq PLTV-3250 wont start

Oohhhhhhhhh!

Actually, not a "load" but a measure of safety in the event you cross the wrong terminals. I don't want glen65 to cross a high power source by accident and damage the supply. The resistor prevents that, but on the correct line, it will pass a sufficient amount of current to start the PSU.

So, it's like a circuit breaker or a fuse? (in Mortal language )

[Toasty]

Re: Spectroniq PLTV-3250 wont start

So indeed, this is more an ATX, computer-style SMPS, than a "regular" LCD PSU?

Yes

I know that after the big cap and partially rectified voltage (half wave) there could be ("could be" because I'm not an electronics expert, I'm learning on the go...) at least a 120v (input V) half-rectified...

AC voltages are normally specified in terms of their RMS values. 115v AC is an RMS value. The RMS (Root Mean Square) voltage is called the effective voltage, as opposed to the Peak voltage which corresponds to the Maximum AMPLITUDE of the voltage variations. It's the "working part" of the voltage, or the value where the work gets done that we reference when we speak of the 115 volt power at the outlet.

If you take 115 volts and multiply it by 1.414 you get 162.61 volt. Voila! The 160 volts he's talking about. The 162 volts is the Peak voltage. Since it is passing through at least one of the rectifiers, and he's measuring on a DC scale, he'll see that peak voltage, especially across the cap.

With there being no load on the supply, as it is not working, discharging that cap is a critical safety matter before working on this supply.

Here's some light reading:
Power Transformer The bottom part of the text gets into the tasty bits. But, the whole page makes for good reading.

Root Mean Square

What is RMS value

...that 1/2 w resistor might be the load required to start the ATX "engine", right?

Actually, not a "load" but a measure of safety in the event you cross the wrong terminals. I don't want glen65 to cross a high power source by accident and damage the supply. The resistor prevents that, but on the correct line, it will pass a sufficient amount of current to start the PSU.

Cheers!
Toast

[Toasty]

Re: Spectroniq PLTV-3250 wont start

A jumper from ground to which terminal?

Don't know. You didn't answer my questions.
Read the paragraph again that starts with "Now, regarding the way..."

Did you try to contact FSP support for a schematic or a replacement?

Are you talking about connecting the resistor across the 5 volt line itself?

No!

For safety's sake, I do hope you are testing this with an isolation transformer.
Please remember that this circuit is live to the house current.
Getting yourself across any point to ground could be deadly.

Toast