WG D9400 Neck Board - Burn't Out Components (UK)

[Jollywest]

Hi,

I have Wells Gardner 27" D9400 VGA Arcade monitor which I've received in a non-working state.

The chassis board components look ok but some of the neck board components have been fried (see photo's attached).

Would it just be a case of swapping out these components or is it possible there is other issue's which have caused these components to fail in the first place? ... Thanks

[Jollywest]

I've been looking for a direct replacement for this neck board but haven't had any luck, so I'm trying to repair it.

The burn't out components are;

Transistor - Q813 (NPN, HSD1609, TO-126ML)

Resistors - R803 R823 R843 (10 Ohm 1/8w)

Resistors - R806 R826 R846 ( * Ohm 1/4w)

I've also been advised that IC 801 (Video Pre-Amp LM1269A/LM1267A) is probably faulty too.

The issue I'm having is trying to find out the value of the burn't out resistors noted above; R806 R826 R846.
The coloured bands have been burn't away and all I can see is 1 green band on the end of two of them.
I've also checked them with a multimeter but they return no value.

On the schematic for the monitor which I've linked below, these 3 resistors just have an asterisk next to them instead of a Ohm value and they are not listed in replacements parts list either.

Any ideas?

https://www.wellsgardner.com/pdf/Schematics/D9400.pdf

EDIT

Or if anyone has a WG D9400 monitor and could take a close up picture of the neck board, that would do great.

[Jollywest]

Ok I've acquired a replacement chassis for the monitor, however when I've checked the yoke, the horizontal impedance is a lot higher than what it should be (4 ohm instead of 0.4 ohm), and on closer inspection under the anode cap I found this;





Does this mean the tube and yoke are also shot?

[MonMotha]

Whoo, that's a lot of arcing.  Sounds like it probably arced to the yoke (and maybe elsewhere).  Might be toast :\  Was this maybe run without the dag ground strap connected to the neckboard?

[Jollywest]

Whoo, that's a lot of arcing.  Sounds like it probably arced to the yoke (and maybe elsewhere).  Might be toast :\  Was this maybe run without the dag ground strap connected to the neckboard?

I received the machine and monitor like this, so I couldn't say for sure but all the connections to the chassis/neckboard (including ground) were connected when I first looked.
If I were to ft the replacement chassis to the tube as it is, would it knacker the chassis as well?

[lilshawn]

you have a seriosu probrem here.

i agree, this tube has been run ungrounded.

problem is, when you do that, high voltage starts to build up and tries to leak out anywhere it can. it's like a leaky bucket...the more water you put in, the more it leaks.

what's happened is that high voltage has built up enough that it has escaped through arcing out under the anode cap, and out through the color guns (frying the transistors and associated circuitry.) it's supposed to have spark gaps to reduce this happening...

the next problem is A LOT of stuff is going to be fried...likely including the tube itself. high voltage and the color "guns" don't mix well. (50v =/= 25000 volts) even if the tube faired out okay, the yoke...the chassis... i dunno man, i'd cut my losses now and toss it before you start dumping money into it.

i wouldn't put any chassis on there unless you properly measure the yoke with an LCR meter...and even then...test the tube to make sure the guns haven't been melted into tiny blobs.

the high voltage has gone through the color guns, out the neck, through the neck board and found ground through the resistors ( R806 R826 R846) and through IC801

since q 813 is toast i'd suspect q803 and q823 are toast too....the only path to ground frying  R806 R826 R846 is q801 q811 q821, they are toast too.

since the output resistors of the amp IC are fried, q801 is fore sure toast... and likely q802 (the OSD chip since it uses an input on q801) which also means possibly the main IC on the deflection chassis is fried. game over man, game over.

it's a can of worms.

[Jollywest]

you have a seriosu probrem here.

i agree, this tube has been run ungrounded.

problem is, when you do that, high voltage starts to build up and tries to leak out anywhere it can. it's like a leaky bucket...the more water you put in, the more it leaks.

what's happened is that high voltage has built up enough that it has escaped through arcing out under the anode cap, and out through the color guns (frying the transistors and associated circuitry.) it's supposed to have spark gaps to reduce this happening...

the next problem is A LOT of stuff is going to be fried...likely including the tube itself. high voltage and the color "guns" don't mix well. (50v =/= 25000 volts) even if the tube faired out okay, the yoke...the chassis... i dunno man, i'd cut my losses now and toss it before you start dumping money into it.

i wouldn't put any chassis on there unless you properly measure the yoke with an LCR meter...and even then...test the tube to make sure the guns haven't been melted into tiny blobs.

the high voltage has gone through the color guns, out the neck, through the neck board and found ground through the resistors ( R806 R826 R846) and through IC801

since q 813 is toast i'd suspect q803 and q823 are toast too....the only path to ground frying  R806 R826 R846 is q801 q811 q821, they are toast too.

since the output resistors of the amp IC are fried, q801 is fore sure toast... and likely q802 (the OSD chip since it uses an input on q801) which also means possibly the main IC on the deflection chassis is fried. game over man, game over.

it's a can of worms.

  

Well thats a bit of a ---Bad words, bad words, whatcha gonna do? Whatcha gonna do when saint censors you?---!

I appreciate the detailed info though.

Think I'll be taking your advice and getting rid then.

Thanks