Author Topic: Electrohome G07CB0 post cap kit problem (Read 3411 times)

MaineEvent · « **on:** May 11, 2009, 08:08:28 pm »

Hi guys,

I've tried searching boards all over the place for the cause or fix to this problem....
I just picked up Caliber .50 for my first arcade game for $50, AND I LOVE IT! But the screen has this weird dark blob in the bottom right corner when I first turn it on.

After a few minutes it seems to warm up and the blobs separates into 2 and eventually one thick line(s) running horizontally.

This has got to be the original monitor and I'm pretty psyched that I can get this much out of it....

anyone have ideas on how to fix it?

Thanks in advance!

MaineEvent · « **Reply #1 on:** May 11, 2009, 10:23:25 pm »

Also a bit of an update...might be unrelated.... I just realized that the screen isn't only off center (the right side of the picture ends well before the monitor does, resulting in a black border on the right side) but I'm missing the top of the screen as well... can't even see my score. It's like the screen is stretched too far for the monitor? I tried adjusting the knobs on the monitor chassis, but I quickly realized it was just for brightness and sharpness.

Kevin Mullins · « **Reply #2 on:** May 12, 2009, 12:25:28 am »

Damn .... I swear I just read somewhere about an issue like this.

Never experienced it myself and trying to rack my brain as to what the other guy found out on his.
(I know this doesn't help ya at the moment)

Ken Layton · « **Reply #3 on:** May 12, 2009, 12:45:46 am »

Your monitor definitely needs a capkit and a width coil.

In particular, capacitors C107 (10 uf @ 250 volts) on the neckboard and C905 (10 uf @ 250 volts on the main board) generally cause the "picture blob" or dark band you describe. I'd bet that C107 is leaking on the neckboard. Be careful: the polarity is not marked on the board so pay attention to the polarity markings on the original capacitor and install the new one the same orientation.

MaineEvent · « **Reply #4 on:** May 13, 2009, 01:10:21 pm »

Excellent, thanks so much Ken!
I placed my order with Mr. Roberts and am looking forward to fixing it up.
I'll try and take pictures as I go.....

THANKS again for your mastery!

Kevin Mullins · « **Reply #5 on:** May 13, 2009, 03:27:18 pm »

Ahhh... I found it.
I had been browsing through Randy Fromm's Big Blue Book when I saw it.

The "Bypass Capacitor" coming off the H.O.T. seems to be the cause by his description.
Glancing at the schematic it appears to be C511 (47uf 160v) to me.

Which should be in the cap kit, so you should be good to go.

MaineEvent · « **Reply #6 on:** July 01, 2009, 11:38:35 pm »

Okay so before I received my cap kit, I continued to try and play my game with the blob there....wasn't too bad for 20mins or so... then after 20 mins the monitor started getting worse and flickering like crazy and became unplayable......shortly after that the monitor would just pulse when I turned the cab on...sometimes the monitor would start working after being on for a little while......Then I got the cap kit!

OK so Ken and Kevin were totally right with their advice! I installed the cap kit and powered it up. Picture came on nicely no blob and no pulsing....
but it looks like the vertical hold is way off... I tried adjusting the v.hold, v.line, v.height, etc. but that didnt change much. Also I was lazy and didn't replace the metal shield cover while replacing the caps ( is that bad?)

I did not change out the width coil cause the one in there was really hard to remove ....is it normal for it to be covered in glue connected to other caps? or black stuff?

Ken Layton · « **Reply #7 on:** July 01, 2009, 11:59:24 pm »

It's your "H Freq" (a.k.a. horizontal hold) that's out of adjustment.

It's completely normal to need to readjust some controls after installing fresh electrolytic capacitors.

MaineEvent · « **Reply #8 on:** July 03, 2009, 01:04:46 am »

Alright, I tried adjusting all the "pots"? again, including the H freq...but it still didn't get any better. The H freq did change the super horrible whining sound in certain positions....I even tried adjusting the +B which didn't seem to do anything either....
I'm totally out of ideas

Ken Layton · « **Reply #9 on:** July 03, 2009, 01:19:16 am »

You plugged in the video/sync connectors back in the correct spots?

Kevin Mullins · « **Reply #10 on:** July 03, 2009, 10:13:40 am »

Quote from: MaineEvent on July 03, 2009, 01:04:46 am

I even tried adjusting the +B which didn't seem to do anything either....

And don't just blindly adjust the B+ ... you need to measure that voltage.
Measure it, adjust it, set it, and don't touch it again.

MaineEvent · « **Reply #11 on:** July 09, 2009, 02:11:57 pm »

Alright, I'm trying to set the +B1 voltage, but I'm having trouble finding out what it should be at. I've done a few searches and I did have a link to the online manual for my cab, but the link isn't good anymore. Any thoughts?

Thanks!

Kevin Mullins · « **Reply #12 on:** July 09, 2009, 03:07:47 pm »

120v DC

http://arcarc.xmission.com/PDF_Monitors/Electrohome%20G07%2013in%20and%2019in%20Color%20Raster.pdf

Measured on the LARGE white ceramic resistor R1, on the white wire side closest to the tube.

MaineEvent · « **Reply #13 on:** July 09, 2009, 04:14:52 pm »

Excellent help thanks Kevin!
So the large white ceramic resistor is only putting out 53V at the highest setting that I can adjust the +B1 to.....

MaineEvent · « **Reply #14 on:** July 10, 2009, 03:03:34 pm »

Wait... so I'm not going to lie, it's my first time using a multimeter....
When I'm checked the DC voltage I had it on the section with this symbol

and got 53V

the one with the wavy V

got me 117V

Is there a chance that one of the "new" caps that I put in is bad, and I will have to painstakingly find out witch one it is?

Kevin Mullins · « **Reply #15 on:** July 10, 2009, 03:22:28 pm »

Top symbol is DC
Bottom symbol is AC

Where did you have your Negative meter lead - Ground
Any part of the metal chassis should do or like one of the heatsinks, etc.

The fact that you actually have an image coming up tells me the B+ shouldn't be that far off.
(but should still check and adjust it to know where it's at since you messed with it)

Looks more like a SYNC issue now from the picture above. Try adjusting the Horizontal Frequency a bit.

Did you do the "sync mod" when you did the cap kit?

MaineEvent · « **Reply #16 on:** July 10, 2009, 03:52:22 pm »

Thats what I thought...DC and AC.... ok So I have adjusted the +B to read 120V DC now (YAY

)
I have adjusted the V. HOLD, V. LINE, V.HEIGHT, V.FREQ numerous times in different orders and positions. The only change I get is in the overall size of the picture height and width wise. the scrolling has never changed.

In the instructions for my cap kit from Bob Roberts, It advised me to resolder the video/sync input headers (E1-E6 and J1,2,3).....it said they loosen up and have usuallybeen resoldered. Mine looked great with the exception of one that I touched up so I didnt really touch them...... but I did remove C501 and replace it with C303 10uf50v which was listed as an "Upgrade"

Kevin Mullins · « **Reply #17 on:** July 10, 2009, 04:08:12 pm »

Quote from: MaineEvent on July 10, 2009, 03:52:22 pm

but I did remove C501 and replace it with C303 10uf50v which was listed as an "Upgrade"

Yeah, that's the slight mod for newer games.

How do you have the sync lines hooked up?
On the three pin connector.

MaineEvent · « **Reply #18 on:** July 10, 2009, 04:20:16 pm »

here's a picture

I was looking at this...
http://www.homearcade.org/BBBB/sync.html
So I think I am going to re-solder the E's and J's mentioned just incase

Kevin Mullins · « **Reply #19 on:** July 10, 2009, 06:12:31 pm »

Looks like you need to move J2 over one pin from that angle...... like the sync wire isn't even going to anything.
Or even flipped around, not sure what your yellow and white wires are. (sync & ground ?)

MaineEvent · « **Reply #20 on:** July 11, 2009, 03:41:23 am »

According to that link... it is the horiz and vert negative sync.
I've tried moving it over... backwards....it didn't change anything

Kevin Mullins · « **Reply #21 on:** July 11, 2009, 07:31:39 am »

Are your yellow and white sync wires tied together somewhere ?
That being a JAMMA game it should be negative composite sync.....trace those lines back to the JAMMA harness connector and let us know what you find.

MaineEvent · « **Reply #22 on:** July 13, 2009, 11:01:21 am »

I fixed my problem!!!!
It was HUMAN ERROR While changing the position for C303 I had the cap in the wrong 2 of 3 holes! Totally a rookie mistake made by a rookie.
Thanks for all your help Kevin, I really appreciate it!

It was soooo satisfying to get to play a couple hours of Pacman, Donkey Kong, 1943 and Galaga last night.

Kevin Mullins · « **Reply #23 on:** July 13, 2009, 01:39:29 pm »

Quote from: MaineEvent on July 13, 2009, 11:01:21 am

I fixed my problem!!!!
It was HUMAN ERROR While changing the position for C303 I had the cap in the wrong 2 of 3 holes! Totally a rookie mistake made by a rookie.

Well that's cool you found that..... part of the SYNC mod.

Something like that we probably would not have been able to help you with, so you did the right thing by backtracking and double checking your work from the sounds of it.


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