Help, graphics problem

[xxdrjewxx]

I've search a lot and cannot found how to repair the issue, i found a thread on atariage forum from someone who had the exact problem, he said he fi ally fixed it by changing a chip, cant remember the name but i cannot fond any chip with the same name on the vectrex and no mention of it in another forum or web page. When i turn on the vectrex it displays fine, the vectrex name comes up but then after like 5 seconds the letters become just lines, then the game starts and you can see parts of the game but a whole lot of lines coming out from the center of the screen. See the pictures attached. I am no expert on electronics, i opened it up and cant see any capacitors leaking or any cables out of place or rust anywhere. Please help if you have any trouble like mine.

ibb.co/vmjwLmG

ibb.co/7JmGKpD

ibb.co/vV6NW17

[Peer]

Hi there,

I am not an electronics expert either, and you most certainly already checked this. But just to be sure, have you tried the brightness potentiometer at the back of the console? The pictures look like the brightness is cranked up to the max, so that not only the drawn vectors but also all movements of the beam can be seen as lines.

Cheers,

Peer

[xxdrjewxx]

Sorry i forgot to mention that, yes that was the first thing i tried, it didnt make any difference unfortunately.

[Peer]

Jan 26, 2021 11:43:33 GMT -5 xxdrjewxx said:

... it didnt make any difference unfortunately.

You mean no difference regarding the "lines"? Or do you mean no difference regarding brightness?

If turning the poti does not alter the brightness, then it could be a broken poti which is stuck at the max.

[xxdrjewxx]

It didnt make a difference with the lines, the brightness adjust just fine but it doesnt seem to have an effect on the lines, they are still there, they go down on brightness too when i adjust the knob but they dont disappear.

[Peer]

Ok, then it is definitely not the poti.

Looks like for some reason the BLANK signal information is not "handled" correctly by the hardware. You could try to replace the VIA chip by a new one or a spare one. That is comparatively easy as the VIA is socketed.

As I said, I do not have any deeper knowledge of the Vectrex hardware. Maybe some of the electronics experts around here could chime in?

I will try to contact  one of my former students from Electrical Engineering who own a Vectrex console and who knows much more about the inner details than I do. Could take a while as right now (this week and the next two weeks) all the final exams of this semester are taking place.

[drsnuggles]

Hi,

jumping in even without special Vectrex hardware knowledge.
First if have to say some warning words because you said you are not an expert in electronics.

!!! DANGER !!! HIGH VOLTAGE !!!

The Vectrex is not only electronics, it also contains a CRT which can be harmful.
Even unplugged it can kill you. The Vectrex CRT operates at 5800 Volts!
Energy is stored in capacitors and even low voltage is discarged in such short time that this can kick you through your room! No joke!

Hope you already know that good enough if not please consider watching repair videos which show how to handle CRTs and hardware correct. Stay away if you are not 100% sure what you are doing.

-------------------- END OF WARNING ------------

Guess i found the link you where referencing
atariage.com/forums/topic/118619-vectrex-display-problems-pics
on page 2 they mention M8320-LF347N

Thanks to Helmut for some general repair docs
www.vectrex.de/wp-content/uploads/2013/06/Vectrex-Service-Manual.pdf
on page 33 and 35 of the service manual i see some of those op amps (LF347).

Good Luck !! and stay alive!

[xxdrjewxx]

Yes i knew about the crt and how to diacharge them, safety is number 1 on my books, i do carpentry a lot as a hobby (so im very careful) and some electronics repair but by no means have advance knowledge but i did research before opening the vectrex, thanks for the warning anyway. Ill have a look at the manual and see about that chip, couldnt find a replacement anywhere tho, and i cant afford another non working vectrex to take the chip from that one, they sell for a high price even those that are up for parts only.

[xxdrjewxx]

Jan 28, 2021 2:24:48 GMT -5 Peer said:

Ok, then it is definitely not the poti.

Looks like for some reason the BLANK signal information is not "handled" correctly by the hardware. You could try to replace the VIA chip by a new one or a spare one. That is comparatively easy as the VIA is socketed.

As I said, I do not have any deeper knowledge of the Vectrex hardware. Maybe some of the electronics experts around here could chime in?

I will try to contact  one of my former students from Electrical Engineering who own a Vectrex console and who knows much more about the inner details than I do. Could take a while as right now (this week and the next two weeks) all the final exams of this semester are taking place.

Yeah thats super helpful, im not in any rush so if yoj remember to ask them about it that would be totally awesome, thanks for the help, meanwhile ill search for that chip in the maintenance manual and see if i can get that replaced. Thanks

[kokovec]

The VIA would be an obvious culprit.
Although I had a similar problem a long time ago and I believe I had to replace the diode that hangs off the Op Amp (D302).

[xxdrjewxx]

Jan 30, 2021 1:36:54 GMT -5 kokovec said:

The VIA would be an obvious culprit.
Although I had a similar problem a long time ago and I believe I had to replace the diode that hangs off the Op Amp (D302).

Well found the chip and the diode on ebay after Googleling some info about them, about 40 dollars for both of them, not a lot but not cheap either, i havent ordered them yet for 2 reasons.
1 i live in Tijuana Mexico, usually i order anything on ebay or amazon and just go to my po box in the US, just cross the border in 10 minutes and i get my packages that way, but the United States closed the border since march 2020 and i cant cross over, so thats a problem and i dont see it resolving any time soon because of covid. Shipping to mexico is way to expensive and we dont have a great postal service.
Number 2, is there any way to actually check if the chip or the diode is the problem? Or is my only option just to replace them and hope thats the problem?
as i said i just do electronics as a hobby so i dont know much about how the vectrex work, i can definitely change chips and have basic soldering equipment and knowledge but thats as far as i go.
Id like to thank everyone for their help and hope you can keep updating this thread with any info you have.

[kokovec]

I would start by replacing the VIA if it's socketed.
If that doesn't work then you'll need a scope to figure it out.

Looking at the Z-axis with a scope (page 13):
console5.com/techwiki/images/f/f8/Vectrex-Troubleshooting_Guide.pdf