WG K7000 series (now Wei-Ya 826HR) - replaced width adjustment cap, issues...

[Numbski]

Okay, I'm cursed.  That's all there is to it.

I ordered the chasis in the link above.  What I got in the mail was a Wei-Ya 826HR.

I carefully go about wiring it up - given that it came with no instructions, manual, nothing.

Turn the thing on, it immediately blows the 2A fuse next to the AC power in (really a 3A).  I go back, remove the chasis - re-mount it so that it's not touching the frame that holds the tube, put a 2A fuse in, turn it on, blows the 2A fuse - AGAIN, immediately.

I am *so* running out of ideas.  The only thing that has me even the slightest bit concerned was that one wire harness coming off of the tube was colored slightly different from the original, but the connector was the same, right down to the keying.  From keyed end over, the new one was colored  red, blue, yellow, green.  The original one (which is still the one in use) is colored red, blue, brown, yellow.

I did some searching, and I'm starting to wonder - the frame holding the tube - it appears to be connected to the ground circuit running throughout the cabinet - so I am not entirely sure what to think.  The ground wire coming off the neck board is a black wire that turns into a long length of exposed braiding.  I've connected that back up where the old neck board was grounded.  The new chasis had a new R, G, B, sync harness, so I wired that in where the old one was - but given the way that 3A fuse flashed immediately, I tend to think that it's somewhere in the AC/DC transformer that things are going awry.  The thing has it's own "lamp cable", which I've plugged in for now, but would eventually like to remove and wire back into the master power switch for the cabinet.

Suggestions?

[Ken Layton]

Here's the instructions:

http://home.earthlink.net/~arcadeparts/id11.html

Hopefully you did NOT plug the power cord into a wall outlet. This chassis must be powered from an isolation transformer.

[Numbski]

I did.

Based on those instructions, that's the only error I made.  Hopefully the fuse spared me.  I'll replace the fuse, run it through the transformer and pray.

[Numbski]

Okay - replaced the 2A fuse, wired the monitor in via the isolation transformer, fire it up - and the fuse doesn't blow, but I get a solid white screen.  Try feeding it video, still get a white screen.  My signal lines are run in too.  I'm going to work on tracing my cabling to make sure I didn't foul anything else up - but at least the white fills the screen, rather than a nice white box in the middle.

[Numbski]

Update - we have picture.  It's over-saturated, and it's UPSIDE DOWN, but we have a picture.

Make that upside down and backwards.  It's like I have the yoke plugged in backwards, but it matches the pictures...?

Since I'd done so many stupid things - is there any harm in me plugging the yoke plug in the other way?  From the flyback, I have it plugged in red, blue, brown yellow, just as in the pictures.

[Numbski]

ok ok ok - I get it now.  I think.  Someone please confirm before I kill this thing or myself.

The thing is yoke-flipped.  No clue how it happened, but I see in one of the pictures he's cut his plug in half.  So even though it shows red, blue, brown, yellow - I really need it to be blue, red, yellow, brown.  Sound right?

[Numbski]

Well - after months of frustration - I'm back to where I started, only slightly worse off.

Picture is back up - almost completely normal.  The picture is back to being too wide (can't seem to find my plastic tool to turn the horizontal adjustment coil), and now the picture is waving.  I thought maybe the speakers I'd installed were doing it, so I removed those, degaussed, and still get the waving.  On top of that, I'm seeing "refresh lines", coming top to bottom.

So I guess this is progress - so long as I like SFII waving like a flag.

[Numbski]

Found my adjustment tool.  Then I promptly found that the ferrite slug in this thing is flat, and can't be turned.

Well.  It's time for bed I think...I've got the pot on the control board turned all the way down, and in the "dot cloth" screen, half of the squares on either side is overscanned off screen.  Flag waving and refresh lines are still present.

[Ken Layton]

Screen control is probably a tad bit too high and should be turned down a little. I think on this chassis there should be a "N" (Narrower) and "W" (Wider) jumper wire to move that sets the width range.

I also think this chassis has two yoke connectors to choose from: one gives a mirror image and the other gives a normal image.

Never plug or unplug any connectors with the power on. Same with moving the N or W jumper wire.

I'm surprised you didn't get the 825 chassis which is made for 25" tubes. The 826 is made for 26" & 27" tubes I think.

[grantspain]

for the flyback lines adjust the screen volts,its kinda like a pre brightness adjustment-its on the flyback transformer below the focus adjustment

[Numbski]

For once my suspicion was kinda right - (BTW, I've done computer hardware repair, programming, and networking engineering for well over 12 years, my father however was a TV repair person in high school!), and I had my wife watch the screen, I turned the screen pot down until the picture disappeared, and then slowly turn it back until she saw an image again, then turned the brightness back up.  "The flag was still there".  (sorry)


I'll go looking for that jumper.  With everything being in chinese, but with english in fine print, makes for difficult hunting.  Go fig that the the two plugs weren't the same - I was just following the pictures.  Oh well, no harm done.  I'll try finding that jumper, and see if I can turn the screen pot down any further.

[Numbski]

Pulled the board, and you're right - there are jumpers for both H and V, N and W.  Both were already set to N.

There was an adjustment pot for b+, which in my searching I seem to recall someone talking about flagging from a bad b+ cap, but I don't know if an improperly adjusted pot would do the same thing.

So it looks like I'm screwed on width anything I go futzing with the width adjustment cap.  Again.  I'll see what I can do about the flagging before I mess with that.

Anyway, the auction even listed this model number:

[Numbski]

I don't suppose there's a manual for this chassis floating around someplace?  The reason I ask is that I'm looking at the RBG harness - and the K7000 (if I recall) , could either take H Sync and V Sync separate or composite.  The marking on the chasses for the harness is halfway covered, but as far as I can tell it reads:

R G B B S

It occurs to me that this means red, green, blue, BLACK, sync (I had to presume this was ground).

So - I guess I'd like to confirm that this doesn't have the ability to take separate H and V sync.

[Numbski]

Here's the state of things as I head out this morning.  WARNING!  Turn off your speakers - YouTube completely hosed the audio on this recording.  It's fine on my local copy. :\



The waving isn't caused by my camera - it really does look that way, with about 1/2 inch of overscan left and right.

[Numbski]

Hey grantspain, you get around:

http://forum.arcadecontrols.com/index.php?topic=85134.0

That board is very, VERY similar to mind - some pots are populated on his board that aren't on mine, but it's starting to look like the Pentranic CH888 is a very similar, if not identical chassis to the Wei-Ya 826HR.

So - you made a comment about him having the sync wires hooked up wrong.  My signal harness (now that I have a schematic to go by!) is R,G,B,E,S (or I guess it could be G, S) - and it looks the same as his.  I don't see a separate hookup for v-sync though...where were you getting that from?

[grantspain]

o.k i reckon there is a quick fix for this,i am gonna get flamed from the other techs here but what the hell
you chassis is for a 26" tube but you have a 25" tube-so the logical step is to send it back and replace it for the correct one
now if you do not want to do that then there is one other option without messing with cap values
turn down the b+ adjustment,when you do this your height will increase but i reckon you can adjust that out easily

[Numbski]

Now I had tried to turn down b+ this morning, but it had no impact on the waving.  Are you saying that if I crank down b+, adjust out the height that it would fix both the waving AND the geometry? (I'm at work, can't test it just now...)

Just for reference (I *really* don't want to go this route...), can you tell from the Pentranic schematic which cap is the horizontal width adjustment cap?

[Ken Layton]

The "ripple" in the picture could be from your video signal cable being near AC power wires. The video signal cable must be dressed away from any 120 volt AC power wires. It's also possible that when you connected this chassis without isolation transformer you may have damaged an electrolytic capacitor in the monitor's power supply section.

[Numbski]

From a glance at the schematic, L301 is the width adjustment coil with (apparently immobile) ferrite slug, and that makes C315 the width adjustment CAP, with a current value of .39uf (394J/250V).  I forget what caps I have back at the house, but I'm thinking if I do .40uf or .42uf as a last resort I should be in good shape.  That of course presumes I get the waving under control and there's absolutely no other way to fix the screen's geometry.

If someone could be so kind as to verify.    Please....I'll send out beers over TCP or something over this.  Amazon wishlists?

[Numbski]

The "ripple" in the picture could be from your video signal cable being near AC power wires. The video signal cable must be dressed away from any 120 volt AC power wires. It's also possible that when you connected this chassis without isolation transformer you may have damaged an electrolytic capacitor in the monitor's power supply section.

Yeah - I was kind of afraid of that.  If that's the case at least it's not TOO big of a deal to find those caps and replace them. :\

[grantspain]

the wave is nothing to do with the geometry problem
you probably screwed the mains filter cap when you connected this direct to mains

the b+ is something i would be a lot happier adjusting down rather than messing with cap values
b+ adjusting up=bad
b+ adjusting down(a little)=no big deal

[Numbski]

Well - turning B+ all the way down along with the width pot all the way down does nothing. :\

So far as the waving, the mains filter cap - if J801 is the mains coming in, that makes T801 a switched transformer (I think?), so C801 is the "filter cap"?  I'm not too good at this, it is labelled 0.22U/250V I'm not sure what the capital U stands for.  Is it just a .22f cap?

[grantspain]

well first time i have ever heard of the b+ making no affect
perhaps you have killed the b+ filter cap

[Ken Layton]

Main filter capacitor would be the largest (physical) electrolytic capacitor on the main board.

[Numbski]

So far as I can tell, this is the schematic for this board.  Some of the positions are labelled ever so slightly different, but the values and positions match up.

[grantspain]

ch888 is a free voltage chassis that runs without the need of an isolation transformer,are your sure that it not a ch666 chassis which 120v isolation only

[Numbski]

Well, I have the chassis out now.  That would explain the labelling differences.  I'll take some hi-res pics here in a few minutes - is there any relatively fast way to tell?

BTW - the filter cap on this board (based on Ken's description) is 680uf 200WV - that would tend to corroborate your idea, since they'd want at minimum a 250WV cap there I'd think, and in fact on closer inspection, the schematic here calls for a 250V.  Lemme go pull the ch666 schematic.  Dang this thing matches so closely though...

[Numbski]

Are you sure you don't have those backwards?

CH-666 (Analogue Chassis – CGA/EGA/VGA) - 28", 29", 38"
CH-888 (Analogue – CGA) - 14", 17", 19", 20"

I think we're both wrong and it's this one:

CH288 - CGA (Analogue - CGA) - 26", 29", 33", 38"

[Numbski]

Okay, so one is the overhead view, the second is what I think is the filter cap.  My side views came out blurry, so I'm going to re-take those.  Compare with this image from the other thread:





I don't have the yoke plug attached, so that seems to be glaringly absent, and the top-left set of pots is not populated, but that's because they've wired it outboard (attached).  The general layout and just about every component matches up.

[grantspain]

sorry i was helping someone with a 666 in another forum and got confuzzled
again the 288 is free voltage
now the 988 is 120v only so check that out

[Ken Layton]

That's not a picture of a Wei-ya chassis. That's a Kortek.

[Numbski]

Ugh - you've got to be kidding me.  They sent me a Kortek chassis in a Wei-Ya box???  Sheesh.

(oh wait, the top image is someone else's chassis, the bottom pictures are mine)

[grantspain]

wei ya and rodotron are basically the same although there are some variations,the basic chassis is the same
i have been looking at your pic and the 988 schem and i believe they are the same

your chassis is without doubt a 120v isolation chassis

also i wonder if the wave problem is down to the degauss,try the monitor with the degauss disconnected otherwise i would go for the large filter cap in the top right hand corner
important to check those diodes as well in the bridge circuit

[Ken Layton]

The large 680 uf cap is the main filter.

I now see your pictures correctly. Earlier when I clicked on them I had a "permission denied" page pop up.

On your chassis is a second red wire jumper near the wide-narrow jumper. What does this other jumper do? What are the markings next to it?

[Numbski]

I'll check in a moment.  I managed to snag a replacement filter cap locally.  The waving remains.   I guess the B+ cap would be next. :\  I believe the other jumper was Vertical Wide/Narrow.  I'll check as soon as I can.  I haven't tried running without the degauss cables hooked up.  I can try that too, but I'm puzzled as to how that would help.

[Numbski]

Okay - the jumper nearest to the width adjustment coil is labelled "V", with two choices "W" and "N", with "N" selected.  The other one is labelled "A", with the same two choices, "N" selected.

[grantspain]

I'll check in a moment.  I managed to snag a replacement filter cap locally.  The waving remains.   I guess the B+ cap would be next. :\  I believe the other jumper was Vertical Wide/Narrow.  I'll check as soon as I can.  I haven't tried running without the degauss cables hooked up.  I can try that too, but I'm puzzled as to how that would help.

coz i am wondering if the degauss circuit is constantly on-which would cause waves

[Numbski]

Running with the degauss cable unplugged makes no difference, the waves remain.

The two yoke plug outlets behave differently - one runs the picture upside down, the other is backwards.   No matter which you choose, you have to yoke flip.

So what really should be the next step here?  I get the feeling I should tackle one problem, then worry about the other.  Since we know it's not the filter cap causing it - I've gone and cleaned up any A/C wiring that could be suspect, and it doesn't appear to make any difference - the signal cables are well clear of any A/C wiring.

I suppose I could order a cap kit for the thing, but we're kind of chasing our tail at that point.

Pentranic doesn't list a 988 model schematic for download.

[grantspain]

i would send the chassis back and swap it for a 25" version,just tell them it did not work on arrival-wei ya and rodotron are crap quality control anyway,i have had 4 rodotron and 2 wei ya chassis and had to repair 3 of these on arrival due to bad soldering
the yoke thing would require you breaking the yoke plug in two

you have so may different issues with this chassis that it seems pointless trying to get it right

[Numbski]

I'm inclined to agree, but *dang* this is frustrating.