Re: Gravitar text color/WG6100 issue

Thanks for more great info !

Yeah, I do see the difference between flicker and jitter. I've got a 25" Amplifone on my SW and when there's much text on screen, the flickering is quite apparent. The jitter means (in this case) that you can see that it's not exactly the same pixels being hit on the screen. Sometimes the next pixel (f.i. to the right) is hit.

In general I would say it looks like there's a "wave" going over the screen, which would mean an extra AC on top of the deflection signals.

Now, I had measured the HV before and already noticed it was pretty low. However I use a pretty old single unit (Zenith) to measure. Although it has been good so far, I thought it might be misindicating, but I just checked B+ and it's only 155Volts !
Pretty big difference from what it should be.

Of course I'll have to adjust that.
Will the screen intensity increase if I up the HV ? Anything else I should watch out for while upping the HV ?
Could this also cause the problem ?

I'm quite surprised it's running as good as it is right now with that low B+....

My meter is a Fluke that get's calibrated every year (it's from my work). I did measure through the side of the monitor, so this metal plus the contacts to the rest of the frame could well build a resistance like 1 Ohms I guess.
I'd have to measure through the harness to get a true view on the connector's resistance. I did easily pull out the red pin at one time. I will advice the owner to replace all the pins anyway.

The wire-wound resistors look to be the original one's. I think the jitter is too little that these could be the cause.

Thanks !!!

Op 23 mrt 2010, om 23:22 heeft William Boucher het volgende geschreven:

> Sounds like you've done lots of good work there. Don't confuse flicker with jitter. The hi-score screens on Gravitar/BlackWidow/SpaceDuel always show their slow refresh rates most on the hi-score screen.
>
> I doubt that recapping the ARII will eliminate any remaining monitor jitter but it's certainly worth a try. It regulates the +5V, +12V and -5V supplies. It does not regulate the plus/minus 22VDC outputs. Replacing C18, C19 (3300uF,35V) may help a bit though because these supply the vector generator section. However, since they are regulated down to plus/minus 15V locally in the vector generator section, I would expect there to be little or no ripple after those two Vregs.
>
> The 1ohm resistance you are measuring... is it possible that it's just your meter? Two-wire meters tend to be pretty inaccurate below a few ohms. What does it read if you just hold the probes directly together? A true 1 ohm resistance through a molex connector terminal on a power supply rail is a whole lot. If the monitor were to draw 3A through it, it would drop 3V through the connection and the connection would also get very hot (P = VxI, 9W=3Vx3A). The total resistance should be measured in milli-ohms, far too low to measure without a 4-wire ohmmeter.
>
> The B+ should be 180V. The HV output should be 19.5 kV.
>
> Adjust B+ as follows:
>
> <the following quoted from 6100 faq>
> Here is a trick for adjusting R918 without an HV probe. Hook up power to the monitor (but without any input signals from the game board) and let it warm up for about 10 minutes. Now measure the Video B+ voltage either at pin 5 of P900 on the HV board, or at J501 on the neck board (refer to your schematics). Adjust the HV so the B+ is 181v DC. Since the Video B+ and the 19.5 kV outputs are linked together, you will get the HV pretty close to perfect.
>
> <end quote>
>
> Another post from today reminded me of this, check the two big cement wirewound resistors on the 6100 deflection board. Have they been replaced? They must be non-inductive otherwise they'll cause the shakes.
>
>
> William Boucher
>
>
> ----- Original Message ----- From: "Andre Huijts" <a.huijts@upcmail.nl>
> To: <vectorlist@vectorlist.org>
> Sent: Monday, March 22, 2010 6:44 PM
> Subject: Re: VECTOR: Gravitar text color/WG6100 issue
>
>
> Coming back on this:
>
> I just installed and adjusted a LV2000 and it works fine. I checked the xx15 regulators on the PCB and they work fine. Didn't change the caps yet though, need to order them (using _good_ brand caps on this only).
>
> Checked all diodes and they are fine. I did replace C100 and C101 by brand new Panasonic one's.
>
> There is no additional ground wire. Would it be a good idea to try to install one (temporarley) I did measure the resistance between the monitor metal side panel and the ground lug on the power brick and it's about 1 Ohm. Not too shabby I think, or is this already poor ?
>
> I can still see some minor jitter. It seems only there (or only visible) when there's lots of (small) vectors on the screen like with the hi-score screen.
>
> Replacing the terminals in the harness connectors is a great idea anyway, I just had the red pin came loose (causing of course no red on the screen). Pushed it back and it's OK now, but it's too easy to remove it....
>
> Well this cab still has the original Big Blue and the AR-2 is not re-capped either so could that be an issue too ? I think the Big Blue has been blaimed for lot's of troubles too. Thing is I can't measure anything with my Fluke DVM, but how much ripple voltage is really needed to let a one pixel movement be show ? Very little I bet !
>
> Colors are fine after I replaced (and adjusted) the pots on the neckboard.
>
> Thanks for the help so far.
>
> O, I checked HV with my HV probe and it showed pretty low. What should B+ be and where to measure it ?
>
> Thanks, André
>
>
>
> Op 13 mrt 2010, om 21:10 heeft William Boucher het volgende geschreven:
>
>> Regarding the jitter problem...
>>
>> Check the output of the 7815 and 7915 regulators (VR1 & VR2) in the video section of the game board. If one of them is shorted through, jitter will result. I had a board with this fault and replacing the two regulators fixed the problem. Also good to do is replace the caps around these two regs (C111, C121 & C110).
>>
>> On the monitor deflection board, make sure that all 4 diodes D100, D101, D102, D103 are all good. An open diode will result in halfwave rectification instead of fullwave and this will result in a lot more ripple on the DC power supply lines. If you haven't already, replace C100 and C101 (4700uF, 50V). A lot of standard cap kits do not include them because they are the largest and most expensive ones. They are very important however. I have posted an extensive replacement parts here:
>> http://www.biltronix.com/arcade_electcomp_01.html#wg6100_rebuild_parts
>>
>> If someone has added an additional ground lead somewhere, just temporarily remove it. These add-on leads often cause jitter issues because they can create a ground loop as well as other issues. If removing the extra wire solved the problem, there are better ways to beef up the ground connection such as replacing the existing terminals in the original harness connectors with new gold ones.
>>
>> Text color problem...
>>
>> Try adjusting the bias and gain pots on the 6100 neck board to get the correct color balance. There is a pair of pots for each color. The manual for the 6100 explains these adjustments.
>>
>> And yes, some text is light blue (cyan). Screen shots (probably mame) on KLOV:
>> http://www.arcade-museum.com/game_detail.php?game_id=8000
>>
>>
>> William Boucher
>>
>>
>> ----- Original Message ----- From: "Andre Huijts" <a.huijts@upcmail.nl>
>> To: <vectorlist@vectorlist.org>
>> Sent: Saturday, March 13, 2010 2:25 PM
>> Subject: Re: VECTOR: Gravitar text color/WG6100 issue
>>
>>
>> Forgot to mention that I also replaced the pots on the Gravitar game PCB to see if these were the cause of the jitter, but they weren't.
>>
>>
>>
>> Op 13 mrt 2010, om 20:18 heeft Andre Huijts het volgende geschreven:
>>
>>> Gravitar owners, I've been working on a WG6100 in a Gravitar and I wanted to know, do we agree that the main texts on the attract screen are meant to be light blue and not pure white ?
>>>
>>> When I compare the texts with f.i. the diamond test screen, the diamond screen looks like true white.
>>>
>>> Can someone confirm this ?
>>>
>>> Another question about WG6100: this one has a very minor "jitter" on the screen. I'd say that there is very small (extra) AC on the deflection signals. It looks like it's mainly on the horizontal deflection but also somewhat on the vertical.
>>>
>>> It causes the beam to not steadily hit the same dots on the screen. Note that the metal screen is INSTALLED on the HV cage !
>>>
>>> Any idea where to look. I just did a cap-kit on deflection and HV board (using Panasonic high quality caps, 105 degr.).
>>>
>>> I did not yet install a LV2000 (it's on it's way). Could it be in the low voltage section ? I did _not_ replace the caps there because the LV2000 will get rid off them anyway.
>>>
>>> I've moved out the monitor out of the cab and ran it, and the issue is the same so it's no cause inside the cab, it's on the monitor itself.
>>>
>>> Any tips welcome, thanks !---------------------------------------------------------------------------
>>> ** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org
>>> ** Please direct other questions, comments, or problems to chris@westnet.com
>>
>> André Huijts
>> andre.huijts@upcmail.nl
>>
>>
>>
>>
>>
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>> ** Please direct other questions, comments, or problems to chris@westnet.com
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>
> André Huijts
> andre.huijts@upcmail.nl
>
>
>
>
>
> ---------------------------------------------------------------------------
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> ** Please direct other questions, comments, or problems to chris@westnet.com
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André Huijts
andre.huijts@upcmail.nl

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Received on Thu Mar 25 18:16:30 2010