Gauntlet Legends NT-2701 Neotec monitor cap on neck board...

[MKFan4Life]

I just installed a cap kit from Bob Roberts and had a couple caps left over.  (I had one cap left over on the last monitor I did that Bob confirmed was likely for same monitor used in a different game and not needed.)  Well, this kit was for my Neotec NT-2701 medium resolution 27" monitor for a dedicated Gauntlet Legends cabinet. 

Everything inside is original to the machine, all serial numbers matching up, so I know the monitor is model for this particular game (Bob messaged me saying sometimes they have variations even if it's the same model monitor if a different game benefits from a particular cap in a certain circuit.) 

Well, after sending him some pics from the neck board where a cap in the kit was supposed to go, we thought a capacitor may have been knocked off the board accidentally by a previous owner.  The solder position for the cap had one lead hole smoothly soldered over like I have seen when a cap is not supposed to be installed there, but the other lead hole appeared to have a lead from a previous cap still hanging in the solder, out the solder side of the neck board. 

Upon deciding to go ahead and install the cap, I melted the solder, but could not find the tell-tale old cap lead in the removed solder.  So I wondered, maybe the manufacturing process left a pointed-looking solder joint instead of a smooth one like the other lead hole, and that a cap was not required there after all. 

 I went ahead and installed the cap, but after getting ready to reconnect the chassis, I had second thoughts and removed it from the position in case it could cause problems.  Now my monitor looks much better, and a cap that had went bad for pincushion control is working again, since my pincushion pot works right now. 

The only problem I seem to notice is that until my screen starts to warm up (if the machine hasn't been on that day) the screen seems to be a little shaky... like it is wanting to maybe go in and out for just a split second.  Then as soon as it has warmed up and the clarity looks perfect it exhibits no problems whatsoever. 

Actually, it seems to look better and better the longer it is running.  It exhibited this even before the cap kit was installed, and it always improved as the monitor warmed up more.  I was hoping it would stop this when the kit was installed, but I am happy the colors are slightly more vibrant, and the pincushion problem is gone. 

My real question is:  Would a new flyback cure this problem?  And if anyone has this same model monitor, especially in a Gauntlet Legends 27" 4-player dedicated cab, can you tell me if your neck board has a capacitor at position C920?  It should be a 10uF 250V cap. 

If someone confirms this is needed, maybe I can install it and improve this startup problem, since the monitor has always did this.  Thanks for any and all help given!


[edit by moderator: one word - paragraphs!]

[Avinitlarge]

That value cap sounds about right for the RGB transistor feed. I can't be 100% sure but I was a TV engineer for 9 years. That cap could be anything upto 100uf, Usually no more than 47uf though. The shaking is usually a fault in the timebase circuit.

[Kevin Mullins]

I'm not really familiar with the NeoTec monitors.... but I have a couple 2701's and various other chassis amongst my parts stuff.
I have seen two versions of neckboards you may find on any of the NeoTec's.

Both of the complete 2701 monitors I have have the version shown in the pic.
(pic found on arcadecup.com)
Neither of them even has a location for C920.
Almost looks like an older version of the neckboard maybe.
But overall the neckboard is very similar to yours and all the others I have.

The 2700 chassis I have has the C920 location and it was the same as you described yours.
One hole was open as if it had been unsoldered, the other hole flat as if nothing had ever been there.

I have a few of the NT-25 series chassis and they varied.... a couple had the cap a couple did not. All had the same neckboard, all had a location for C920.

The two schematics I have for the neckboards show a cap there..... but one shows a 10uf and the other shows a 22uf. (?)

Does any of this really answer your question..... not really. 
Maybe someone else will have an NT-2701 with the same version neckboard as you will chime in.

[MKFan4Life]

Here is my exact chassis & neck board (after new caps in place)... the C920 location is visible, but no cap was there when I recapped the chassis.  Thanks for the replies.  Anyone have a Neotec NT-2701 with this neck board and is there a C920 cap in place?

[Ken Layton]

I don't believe there is a C920 installed.

[MKFan4Life]

I don't believe there is a C920 installed.

     
     Oh thanks Ken.  I came across a bunch of your replies this past week while using Google to research info on this monitor.  Most notable was a page I found where a high school student was working on a couple of Atari San Francisco Rush sit down cabs that both had this model monitor.  He quoted a ton of info on this chassis that he credited to you.

     Especially helpful was info about the missing pincushion pot on the remote adjustment board when the little pincushion board is mounted to the side of the chassis.  I thought someone had broken mine off until I read about that and then removed the remote adj. board to inspect it.  Then I found my culprit causing the pincushion problem. (that dreaded little 5.6uF bipolar cap on the pin board)  Mine had either been getting incredibly hot or was leaking some electrolyte from the base, 'cause it had dark burnt crud all around it on the board. (could have been burnt glue, like Bob Roberts mentioned to me)

     Instead of waiting to get one of the recommended "high frequency" caps via mail, I grabbed a 4.7uF 50V bipolar "axial" cap Radio Shack had in stock (closest match) just to give it a go.  It's working fine, but if what you and others state about the standard caps in that position is true, then I will be replacing it soon.  Just wanted to see if that fixed the problem. 

     Anybody else with one of these models have the C920 cap?

[sarge]

The parts listing calls for a 22uF @ 160V electrolytic capacitor to be installed at C920.  I checked a few of our neotec 2701 models and they all had this capacitor installed at this location.

[MKFan4Life]

The parts listing calls for a 22uF @ 160V electrolytic capacitor to be installed at C920.  I checked a few of our neotec 2701 models and they all had this capacitor installed at this location.

Which parts list do you mean?  The Bill Of Materials List in the Neotec manual that came from the factory for my monitor (covers 2700/2701/2702) says part# 28177-1001 electrolytic capacitor 10UF/250V @ location C920.  Do the 2701's you have include the pincushion board mounted to the side of the chassis frame (where the flyback is)??  If so it likely doesn't have the "Pincushion" pot on the remote adjustment board either.  (It DOES have a DPC "Dynamic Pin-Cushion" pot there, though)  Model on chassis frame reads "NT-27E", & a longer number.  Not sure if that helps.  Label on back of neck board reads simply "NT-2701".  Thanks for the info.

[MKFan4Life]

Thanks for the replies.  Does anyone else have this monitor and neck board THE SAME as the one I posted a pic of, and is there a cap at position C920?  Especially helpful would be someone with this monitor in a dedicated Gauntlet Legends cab, as that would likely be an exact match from the factory.  Thanks!

[sarge]

After looking closer that neck board is for an NT-27E.  This monitor has nothing to do with a Neotec NT-2701.  The parts list for that does call for a 10uF @ 250V.  The only thing I got in my shop close to that is an NT-25E which I think would be the same and it has nothing installed at C920.  If you are having doubts just call Neotec and ask their tech support.  909-626-9889.

[Kevin Mullins]

If you are having doubts just call Neotec and ask their tech support.  909-626-9889.

Brush up on your Engrish ..... sorry, couldn't help it.

But yeah, the 27-E and the 2701's are two different beasts.
(yet another reason I've never messed with the misc chassis's I have)

The schematic I have for a 27-E does show a 10uf at location C920.

[MKFan4Life]

Whoa.  Now I am getting confused guys.  This Gauntlet Legends machine seemed to have all the original paperwork in an envelope in the back of the unit when I got it (used of course), and it had a manual for the NT-2700/2701/2702 in the envelope.  The neck board has the cardboard attached with a silver sticker denoting "NT-2701" on it.  There ARE stickers on the metal plate behind the flyback denoting NT-27E, but what the heck do I have here?  A Frankenstein?  Look at the following pics:

[sarge]

You have an NT-27E.  The parts list that you have does not match an NT-2701.  C920 on a 2701 is a 22uF @ 160V.  Maybe someone put a different piece of cardboard on the back of the neckboard.  They get broken all the time.  I'd look a little closer at your manual.  It sounds like maybe you have the wrong cover or something.  Look at page 3 and see what kind of monitors it denotes.

[MKFan4Life]

The manual looks almost flawless... not modified in any way.  (Same goes for the little cardboard on the back of the neck board)

Until now, I figured this machine was never Frankensteined in any way.  Serial numbers on monitor chassis support bar sticker, cabinet sticker, all three Vegas 777 pcb stickers, hard drive sticker, and visible onscreen when game boots up all match perfectly.

I guess someone could have swapped monitors or chassis carefully, as there are no tell-tale marks on any screws where a screwdriver might have slipped removing screws.  (Although someone DID open the pcb cage at some time, obviously, as screws looked like a phillips slipped around on them at some time.)

Here's some pics I sent Bob Roberts of the BOML from this manual, because he wants to make a pincushion cap kit for the NT-2701's additional pincushion board (which this chassis has, as well as a factory omitted pincushion pot on remote board, which Ken Layton was quoted as saying are known to be associated with the NT-2701 here:  http://www.pinrepair.com/rush/  SCROLL DOWN FOR IT).

I am also including a pic of the front cover I just took.  BTW, page 3 denotes NT-2700, 2701, & 2702 specs.  I'll include that page, too. (BTW: C504 is WRONG in the manual as per Bob Roberts statement.  Supposed to be 1000uF & I have confirmed this when recapping this one.  A 1000uF 25V came out of this position.):

[Kevin Mullins]

The parts list that you have does not match an NT-2701.  C920 on a 2701 is a 22uF @ 160V. 

One of the schematics I have for the 2700/2701/2702 neckboard shows a 10uf 250v cap there. (?) Now whether all three version actually need it ??

That's one reason I decided not to mess with all the mismatched chassis and such I had laying around. Not enough confirmed information on boards, parts and yokes. (besides bad tubes they seemed to be notorious for)

Wasn't the 27-E a revision or replacement for the 2701 due to certain problems?
But it wasn't compatible with a 2701 yoke, etc, etc.
Seems like there has been a lot of mis-information to that as well.

I don't have a 27-E neckboard schematic to compare this one to to see if they are compatible. (might explain the 2701 marked neckboard on his)

[Kevin Mullins]

A complete .pdf scan of that manual would be nice.   

[sarge]

I don't really have an answer for you on your manual.  Your parts list is identical to the one in my NT-27E manual which is very different in an NT-2701.  Your neckboard and chassis are definitely NT-27E models though.

[sarge]

Kevin if you look at the pic of the monitor chassis that you posted up there which is a NT-2701, C920 is located at the far bottom left hand corner.  On a 27E, it is located at the top left hand side.

[MKFan4Life]

A complete .pdf scan of that manual would be nice.   

Yeah, looks like it might help some people out.  I am confident this manual is all-original, at least for the monitor models on the cover... it is just too pristine to have been messed with. 

BTW:  My manual has YOUR EXACT video board schematic in it.  Same exact one it appears.

Whoa you guys are replying a lot while I am typing.......LOL!

[MKFan4Life]

Maybe my monitor was an in-between model when they were switching from the 2701 to the 27-E and many things are the same?  I know when I ordered my cap kit, Bob sent a Neotec COMBINED Model kit.  There ended up being (besides the C920 cap) two other small caps that were not used on this board.  (They were not previously installed, though the chassis had spots labeled for them on it.)  They were filled with smooth solder joints from the factory.

Thanks for all the help.  I really appreciate it!

[Kevin Mullins]

Kevin if you look at the pic of the monitor chassis that you posted up there which is a NT-2701, C920 is located at the far bottom left hand corner.  On a 27E, it is located at the top left hand side.

Hmmmm..... will have to go back out and look at those two 2701 monitors I have in storage.
That was a pic I grabbed off the net, but mine had the same neckboards it seemed. And both had that cap you are describing in the lower left, but I was only looking at the usual C920 location area where the other neckboards I have had it. (like the 27E youe described and the pic posted by MKFan4Life)
I'll look again and see what the actual location number on mine was.

Crazy NeoTec's.....   
I'll probably end up giving my pile of stuff to someone else to mess with. 

Wish they had put actual board designation numbers on things like Wells Gardner does.

[Kevin Mullins]

Hey Sarge..... you were right. That lower left corner cap on mine are labeled C920.
And they are 47uf 160v caps. (?)
The other style neckboard has that location as C924.
(I just didn't look close enough between the two)

[MKFan4Life]

Well does a 27-E chassis usually have the separate small pincushion board on the other side of that metal bracket (near flyback)?  Mine has this board, which I have read is present on 2701's?
 

[sarge]

They both have boards mounted on the side for the dpc, but they are different boards.

[Kevin Mullins]

I have pincushion board schematics for both the 27-E and the 2701.

Oh, and I do have a schematic for the 27-E neckboard. I just wasn't looking close enough earlier. Haven't compared it to a 2701 yet though.

Just compared the 27-E and 2701 pincushion AND neckboard schematics I have......
They are identical prints, all someone did was change the title block.
 

Just at a glance my main chassis prints for both are done the same way..... and I at least KNOW they aren't suppose to be the same.
Talk about mis-information being passed around.

[MKFan4Life]

Sarge, the pincushion board on mine is much larger than the one that appears to be on that 2701 chassis Kevin linked to earlier.  It's visible in my chassis pic, but is on the OPPOSITE side of that piece of metal by the flyback.  (So like you said, different if mine is a 27-E...)

Guys, here are actual pics of my chassis and neck board (posted previously) with pics I took straight out of the Neotec manual for the NT-2700/2701/2702.  Looks pretty identical, wouldn't you say?:

[MKFan4Life]

Lol.  Just noticed the manual has that POT at the lower left corner labeled as "H-OREQ", too, just like the chassis!  Maybe someone had their mind on OREO's that day and fudged it?  Hehe.  Maybe they mean "Horizontal Output Frequency"?  Still a goofy abbreviation for it.