High Pitched Whine - NOT Horiz. Sync

[MonMotha]

Kortek KT-2914F (aka the Betson Multisync - it is indeed the Betson OEM model)

When using Mortal Kombat 2, and ONLY Mortal Kombat 2, everything displays fine, but I eventually and seemingly randomly start to get a high pitched whining noise from the monitor.  It's at a lower frequency than the horizontal sync, something like 10kHz if I had to guess.  The picture stays steady and nothing odd happens, but I'm guessing such behavior isn't exactly good and certainly isn't desired.  I have been turning the monitor off when it happens.  I'm curious what could be the cause of this.  The wiring to the monitor is rather good by arcade standards - RG-59 for the video signals and clean wires for the sync.  The run is approximately 5ft and doesn't cross anything else of note (the power supply is plenty far away).

MK2 is the only game that does this to me amongst what I have access to.  TMNT, NFL Blitz 99, my PS2 (running separate sync, all others composite), and even NBA Jam TE (which runs on the same hardware as MK2) don't have any problems.  Blitz 99 runs medium res, all others run standard.

Any ideas?

[Dennis]

Part of our business is game monitors and not the games themselves, but that said.................Is the MK2 running at a different horizontal frequence than your other games?  ie: 15Khz, 25 Khz, 33Khz, etc.  Generally that whining noise is caused by loose ferrite beads, cores in coils and transformers, or yokes.  Just touching them (watch around the flyback) will generally determine which one, as the noise will either change drastically or temporarily quit all together.  If it's a ferrite bead, a little silicone glue on it will cure the problem.  Sometimes it will work on coils, xformers and yokes, but not always.

[MonMotha]

TMNT, NBA Jam TE, and MK2 are all standard res (i.e. 15kHz horiz.).  Now, I can't say that I've hooked them up to my frequency counter to see if they differ by a few Hz or anything (which is quite common), but the OSD certainly says 15 for each of them, like you'd expect.  Blitz I run medium res (since the monitor can do it).  The PS2 also is running standard res as it outputs NTSC timed video.

[BobA]

It maybe the vertical freq.  The mortal kombat card that I have is the only one that I have to tweak my arcade monitor to display.   It has a really low 53 HZ display where most other games are around 60HZ.  Not sure if the harmonics of this difference could cause a high pitched vibration but you could probably play around with some of the mame screen controls to see if you can find one that causes the whine to go away or change.

[MonMotha]

This ain't MAME   This is the real deal.

NBA Jam TE runs at the same timings (15.8k/54, according to the OSD) on the same hardware (Midway T) and has no problem, which makes me want to believe it's something screwy that MK2 is doing.  It certainly sounds like something is vibrating at that high frequency, much like the flyback vibrates with the horizontal sync, and is likely some magnetic element (inductor/coil or ferrite), but darned if I could tell you what piece it is.

[modessitt]

I assume that when you say that you're other games don't have this problem, that you mean the those boards don't cause a whine with this monitor and not that those games in different cabinets with different monitors don't whine.

If this is true, then your problem is being caused by your video signal input, as this is the only thing different between the games.  Your monitor is whining because it is working to hard to display the MK signal.  This could be because of your frequency, or even a problem with the video ground circuit.

Sometimes a capacitor will start to whine if it is getting to the point where it starting to fade from it's proper tolerances.  If it's been a few years since new caps have been installed, I would try that first to eliminate that possibility.  I would also try using the MK board in a different cabinet with a different monitor to eliminate the possibility of an internal problem with the video signal circuit.

If neither of these options work, I would think it's definitely a frequency compatibility issue.

[MonMotha]

It's a reasonably new ( <2 years ) monitor which hasn't seen a ton of use.  While I've known EL caps to go bad in that kind of timeframe, an inspection of the monitor chassis doesn't reveal any with telltale signs.  The signal from MK2 seems identical to NBA Jam TE in terms of what I can measure - all frequencies are the same to within 10Hz on the horitonzal, and 1Hz on the vertical.  I have not examined active video timings relative to synchronization between the two, but geometry is the same, suggesting that the active video areas are likely the same, as well.  The cabling is exactly the same (I'm just swapping the JAMMA harness over).  I've also completely redone the video harness in response to this problem with no luck.  The fact that NBA Jam TE runs fine on identical hardware with (near as I can tell) identical timings says to me that it's not just some issue with it not liking the mode MK2 runs in.

As far as compatibility, everything is within the specifications published by Kortek.  As to the monitor actually performing to spec, who knows.  Of course, being a digital monitor, it may not be quite so tolerant of drifts during operation, which could be what's happening.  Everything always starts out fine, but generally within 5 minutes this problem crops up.

I can try running it on another cabinet, though I don't have access to any other generic JAMMA cabs - the closest I can get is a Dance Dance Revolution cabinet, which is at least JAMMA for some things, including video.

[modessitt]

Just an idea....

Today I installed a brand-new-out-of-the-box Vision Pro into a Gauntlet II and immediately got a high-pitched wine from the monitor on power-up.

Since I knew the monitor was fine (and after double-checking that the resolution rates where correct), it turned out that the whine was being caused by the 120V power wires to the monitor chassis being routed too close to the flyback and yoke.  Moving the wiring away from the flyback and anode wire caused the whine to go away.  I guess the small amount of magnetic interference from the wires was affecting the flyback, anode wire, or yoke, causing the whine.  I rerouted the wiring and tied it off to keep it from accidentally moving back during moving.

I've sometimes had similar problems with video stability if I don't make sure the video input wires don't get too close to the yoke magnets.

It may be worth checking out on your monitor if the monitor you put into the cab isn't the same kind as was originally in there.  Perhaps the necessity of moving the connector paths for the new monitor has caused a similar issue to occur.

Just an idea...

[MonMotha]

Hum, I hadn't thought of that but it does make sense, and it would seem that MK2 being at a weird vertical field rate (i.e. not the AC line frequency of 60Hz or anywhere near it) could aggrivate things.  My power line does run fairly near the flyback, and this is certainly not the stock monitor.  I still find it odd that only MK2 would do it and not NBA Jam, which runs with identical timings.

I'll certainly give it a shot the next time I'm working on the cab, though.  Need to finish building the CP, too.  TMNT and Blitz await!