1084S-P LOPT+HOT replace

check it with a multimeter not a screwdriver mains tester please.
 
i have 128,26,17 volts readings in the pins of the power supply

---------- Post added 20th February 2014 at 00:49 ---------- Previous post was 19th February 2014 at 23:44 ----------

12.41pm in Athens Greece a beautifull night with 18 degrees Celcius...............my monitor is working again:LOL::LOL::LOL::LOL::LOL:

it was a nusty... welding on a capasitor left of the flyback.
i want to thank you all of you with your help.Harry
 
Looks like I am going to have to learn how to fix these. I now have 2 dead 1084S-P1 monitors :(

I have no idea what I'm doing, so I guess my first step is to learn how to discharge the tube properly and then identify my LOPT and HOT, then start looking for replacements. Pretty sure these are the problem, both monitors make a squealing noise when I turn them on. The power light comes on, but no picture.

One only died last night while I was using it. A bright light came on the screen and then a horizontal line appeared on the screen. I turned it off and then back on and then the squealing noise started.

I'd appreciate any help from you guys :) Also if anyone is in Melbourne, Australia that can fix these it would be even better. I'll pay!!
 
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So... similar problem, power supply squeeks when I turn power on and sounds like a bomb falling in a video game when turning power off. Disconnecting the power out cable connector renders it quiet, unplugging the purity coils makes no difference - so I guess those aren't shorted. No glow in the tube and when discharging I get no spark (nor sound).
https://www.youtube.com/watch?v=ZgMGm2elDUw

Desoldered the "HOT", it's a D1577 (2SD1577) on this 1084S-P, flyback is marked E39144, AT2079, 30102 TY PHILIPS (tiny at the bottom edge) and the manufacturing year and month stamped on the small label placed in an annoying place where it was hard to get a good picture or a good look. The HR 7506 should be a suitable replacement at about €32 with tax and shipping to Sweden...

D1577 seemed to measure OK, base to collector and base to emitter measured 0.50 and 0.56 with diode test, no other reactions with all pin combinations on diode test. So it behaves (with no load) as it's supposed to.
I assume the flyback could be shorted anyway, unless there's some other problem or that the "HOT" is bad although it measures fine. Any advise welcome, I have an ESR meter so I hope I don't have to randomly swap capacitors.

Also resoldered parts on the power board as well as the flyback and hi power parts around it - didn't help.

I might have a spare monitor I could borrow parts from, is it advisable to desolder flyback and "HOT", mount these and see if there's a difference? Should I look for other problems first?
 
that is the right lopt for that monitor...its a philips chassis.

you can remove the lopt completely ,then measure the 125 volt rail when its on to see if its stable.
check the other rails as well.
also check the input voltage after the rectifiers to see if its getting dc,its a switchmode supply.
 
I measured the voltages from the power board and got 127.1V, 25.8V, 16.9V with no load. When trying it in a 1081 monitor it worked just fine.

Removing the orange wire (127.1V) from the connector I also didn't get the whistling sound from the power board - so problem is probably there and probably in the flyback. Going to desolder it and check.

Is the recommendation to swap the "HOT" at the same time? Even if it seems to measure OK?
 
Desoldered the flyback and measured it.

hr7506.jpg

1-2 0.07 Ohm
6-5 0.13 Ohm
6-2 0.30 Ohm
5-2 0.22 Ohm
9-10 1.0 Ohm

7, didn't get any thing to any pin

However I had about 18 Ohm when measuring from 9 or 10 to 2,6 or 5. Those shouldn't be connected, right?

With the flyback desoldered, no screech sounds from the power board when powering on.

The three diodes showing in the image above (right side), are these internal? Should it measure something between pin 7 and one of the wires going out?
Measuring in the right direction between 7 and 11 that should give some measurement, right?
 
Measuring voltages at the power board with the flyback removed:
126V
22.6V
13.5V

Don't know if it's OK, have nothing to compare with, this power board powered the 1081 fine though.

Swapping flyback and the HOT (I read the BU508AF should be fine for replacing the D1577) seems like the right way to go...?
 
Desoldered the flyback and measured it.

View attachment 85932

1-2 0.07 Ohm
6-5 0.13 Ohm
6-2 0.30 Ohm
5-2 0.22 Ohm
9-10 1.0 Ohm

7, didn't get any thing to any pin

However I had about 18 Ohm when measuring from 9 or 10 to 2,6 or 5. Those shouldn't be connected, right?

With the flyback desoldered, no screech sounds from the power board when powering on.

The three diodes showing in the image above (right side), are these internal? Should it measure something between pin 7 and one of the wires going out?
Measuring in the right direction between 7 and 11 that should give some measurement, right?

yes the diodes are internal,there the tripler

as for a measurement across 7 and 11,not necessarily


you could still get resistance across some windings,even when bad

- - - Updated - - -

Measuring voltages at the power board with the flyback removed:
126V
22.6V
13.5V

Don't know if it's OK, have nothing to compare with, this power board powered the 1081 fine though.

Swapping flyback and the HOT (I read the BU508AF should be fine for replacing the D1577) seems like the right way to go...?



yes.for the transistor

and...looks like the flyback is bad
 
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Hi e5frog,

I have the exact same broken model.

Did you source any HR7506 flybacks?

Thanks
Sebastian
 
Thanks, they still have them in stock. Nice, will order there.

Are the D1577 and BU508AF interchangable?
 
Thanks, they still have them in stock. Nice, will order there.

Are the D1577 and BU508AF interchangable?


yes they are.

ill have a look in the service manual to be sure anyway...

EDIT: service manual suggests BU508A just make sure you get one with a plastic case
 
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That's why I also ordered the D1577, I hope one of them is in plastic so I don't need to isolate with a silicon pad or "mica plate"?

So what's the difference between A and AF, material is often the last letters in suck codes. There are all kinds of versions of capsules on both BU508A and BU508AF.
The D1577 that's in there now looks like this with a rather even block of plastic:
http://image.pinout.net/pinout_files/bu508af-phi.jpg

There's these capsules for example:
http://thumbs3.ebaystatic.com/d/l225/m/mUO5NYSm6zayBwDdy2bMaEA.jpg
http://i00.i.aliimg.com/wsphoto/v0/...e-Fast-Switching-Silicon-NPN-Power-font-b.jpg
http://i.kontest.ru/g/000/017/953/17953/BU508A_200x200.jpg
 
i think there all the same bud electrically,i just go by the service manual.and case style that was already in there.

personally i cant be bothered to take my monitor apart to see if the heatsink is connected to anything on the pcb to see if a metal case makes any difference...short wise.


one monitor i have cant use the metal cased ones and thats a 1901 as it would short the power supply out blowing the fuse.

the d1577 is a bu508a and bu508af,just different manufacturer etc all can be used for the same job its just a power transistor
 
Got the ones from Sweden BU508AF and the ones from eBay (2S)D1577.
They're all plastic both of them, the BU version has a flatter part as you can see.

These are supposed to be interchangeable, I haven't decided which one to use yet (neither have I ordered the flyback).
 
Replaced the D1577 with a BU508AF.
Received the new HR7506 flyback yesterday. HR diemen replacement quality is questionable. Pins are not fitting in place of the old ones, because they
are slightly off-center (maybe half a millimeter). So, bent everything to fit, soldered it in and ... TADA, tube gets power again.

Picture is tilted 1 degree clockwise, although the deflection yoke is tightly glued to the tube and has not moved. Don't know if this
was the case before, but I have read about this a few times in different threads.

It seems to have a very high pitched sound that my younger colleagues can't stand, but I cannot hear it anymore.
Picture seems to be ok. Too bad I don't have a DIN9 RGB cable for my amiga at home, will have to get one of these.

What is the best measure to adjust screen and focus potentiometer at the back of the flyback?
Anything else to adjust before putting it back together?

I have already changed the power switch because it was broken.
 
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