GO7 issues- repair or replace

pinnut

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im trying to get a 19inch go7 going, not so good. it was dead as a door nail, no picture, no neck glow, no voltage to discharge after its turned off . i replaced the caps, flyback and HOT.
now i get a full image on the screen, but it looks like no sync. B+ is 120 v. i hooked up a TPG , and it does nothing. usually if its not hooked up quite right, or something is else is wrong, scrolling thru the test will still produce red, blue, green. mine is just a washed out kinda grey, never changes.

other than replacing parts, im not a monitor guy. unless i can get steered in the right direction, i'm going to have to have someone repair it, or get a replacement. its a ms pacman. i think the chassis isnt orig, there are splices in the video signal harness in the game. i had another ms pacman had a WG chassis. ps- the neck board was cracked in transit, i solder bridged over the cracks, test for continuity, and epoxied it for stability.

any ideas, or anybody have a replacement or want to look at it?

thanks
 
one thing i noticed, no real neck glow. even with the lights turned down, i dont think i see one. there was no glow before the new flyback and caps, but no picture either.
 
Check resistors R516 (150k @ half watt) and R517 (180k @ half watt). I bet one or both of them have gone open circuit. You need to unsolder one lead from the board to test. Otherwise you will get false readings when trying to check them in circuit.

Who did you get your capkit from? Did it include the non-polar capacitors for C301 and C520?
 
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No joy , both resistors were in spec , unsoldered. the cap kit did include those 2 BP caps.
i looked very closely at the neck board, saw " possible" cracks in the solder and re-flowed them. kinda doubt it, but did it anyway. i re-test it connected to the tube and report back.
i checked the main board for cracks, didnt see any
 
Progress- i have color now

well,, i have color. the layout of the RGBgnd and syncs on the board are the opposite of the layout on the paper on the frame, so i never had TPG hooked up right. i figured it out from the placement of the ground pins.

now i have a jittery picture, and not full screen. about an inch from the top and bottom. what sync should i be using? i was using -H, -V . it also has pos sync terminals on the board.
whats is correct, and how do i set the dips on the tpg accordingly? im hoping now is just tpg not set up quite right, and maybe some adjustments will finish it. i'll attach a pic of the paper stuck to the frame, i dont think its correct.

i only see 4 pots on the back. is horz freq the same as horz hold?

thanks all
 

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sync on tpg and where connected on monitor chassis need to match. you are correct the paper is not correct because that paper in your picture is a k4900 sticker and not a g07. yes try adjusting that horz freq pot after you make sure your connected on the sync properly.
 
I just went threw alot of what your going threw in the end of my thread on my conversion zoo keeper, and talk alot about sync circuits with a ton of info and links to bob R notes.. on the go7 cbo side theres alot of info.. go to very end of the thread...

https://forums.arcade-museum.com/showthread.php?t=405245

The instructions for your unit are here

http://craftymech.com/tpg/TPG_Manual.pdf

It will output - or + sync on horizontal and vertical, as well as composite sync, you will have to loop the end at the input on tour chassis if using composite sync. Again you can find alot of info about that in my thread link above. It links all over the place to lots of info
 
i need it explained to me like i'm an 8 yr old :) . should i use neg sync or pos sync in my chassis? is one better than the other? should i try composite? if so, how to hook it up?

whats the best syncc to use, and the correct TPG dips for it?

thanks much
 
If you read the manual it says the pin out is

08f30ef902db44b8cf0ab80bcd297a65.png


If you looked in my thread you would have seen positive style hook up

0675d5d62cff24651c0ad01dda5d9e1c.png


Or negative style hook up
b28bbfe28aec2965b4c27354ef53cef2.png


If you read the captions it tells you to loop the horizontal and vertical negative sync at the video input if your using composite single wire out put..

You really need to take time and read and understand it..
 
got the sync dips worked out. putting a scope on them helped. the picture was rolling due to a bad connection from a wire on the neck board to a wire wrap post on the main board. i now have a stable image. only other issue is the image is shifted to the left, there is about one inch of black on the right side. moving the raster jumpers on the main board from left to right and to center have no effect. pots have no affect either, cant move it right, or even more left. what to do?
thanks
 
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