Several hardware issues with Vectrex MB, pls help

[m_emelchenkov]

Hi all!

 

I repairing a Vectrex MB unit. I got the unit by chance (a very rare item on ex-USSR area), then bought original controller, and now want to make it playable.

Please, I need your help with several hardware issues with Vectrex MB:

- After several seconds after turning it on the image starts shaking (noticeable) and flickering (not very noticeable). I think, some motherboard element is problematic, but I have no idea which one to replace, they all visually looks OK.

- Some strange bright central dot with rays from this dot to another dots. Should the dot be there? Should rays be visible?

- The spaceship rotates around, moving the stick does not change anything. The ship rotates only when the joystick is connected. I measured voltage on both joystick's potentiometers, they both have 0.06V in the central position and changes from 0 to 0.1V when moving the stick.

- Sound noise level is normal? I know about mods for sound subsystem, but unsure if a such noise level is a standard for this console (the volume is minimal, I can increase the volume, it will be very loud, but the noise will be the same).

 

I recorded a video with all these issues to be more illustrative: https://youtu.be/y73LAskiXbg. Sorry, it does not show the shaking and flickering issue very well, because I recored it from a hand, not from a tripod.

[gtoal]

Hi all!

 

I repairing a Vectrex MB unit. I got the unit by chance (a very rare item on ex-USSR area), then bought original controller, and now want to make it playable.

Please, I need your help with several hardware issues with Vectrex MB:

 

- After several seconds after turning it on the image starts shaking (noticeable) and flickering (not very noticeable). I think, some motherboard element is problematic, but I have no idea which one to replace, they all visually looks OK.

Yes, this will require proper debugging. Most likely capacitors to be replaced.

- Some strange bright central dot with rays from this dot to another dots. Should the dot be there? Should rays be visible?

There is a brightness control on the back. Reduce the brightness until the rays disappear. If that doesn't help it is another hardware problem that will require debugging.

- The spaceship rotates around, moving the stick does not change anything. The ship rotates only when the joystick is connected. I measured voltage on both joystick's potentiometers, they both have 0.06V in the central position and changes from 0 to 0.1V when moving the stick.

You'll find a lot of hardware description online for the voltages for the joystick and buttons

- Sound noise level is normal? I know about mods for sound subsystem, but unsure if a such noise level is a standard for this console (the volume is minimal, I can increase the volume, it will be very loud, but the noise will be the same).

Yes, that's normal.

I recorded a video with all these issues to be more illustrative: https://youtu.be/y73LAskiXbg. Sorry, it does not show the shaking and flickering issue very well, because I recored it from a hand, not from a tripod.

[m_emelchenkov]

Yes, this will require proper debugging. Most likely capacitors to be replaced.

Probably. But which ones, it is still a question. I just found Troubleshooting Guide, I'd like to try its recommendations, but am I understand correct that I need to load a test cartridge before doing any measurements (including those ones with oscilloscope)? It's a problem to me, I don't have a Test Cartridge, only Multicart with Test Cartridge ROM loaded, but can't run it due to joystick malfunction.

 

There is a brightness control on the back. Reduce the brightness until the rays disappear. If that doesn't help it is another hardware problem that will require debugging.

It helped. Thanks! And sorry that I did not notice the forum topic about this issue, it was already covered on the forum.

 

You'll find a lot of hardware description online for the voltages for the joystick and buttons

 

I'll look. When I will fix the joystick I'll be able to load Test Cart and try to debug display shaking.

Edited October 18, 2018 by m_emelchenkov

[m_emelchenkov]

I want to fix joystick issues first. According to info I've found about its voltage:

GND (pin <--> -5V (pin 9) — I get 4.72V

GND <--> +5V (pin 7) — I get 4.89V

GND <--> analog X (pin 5) — I get 4.72V at center and +- 0.1V at stick's extremum positions. But I should get 0V at center and 3.4V at extremums.

 

So... how to debug it, where is the problem could be?

Edited October 18, 2018 by m_emelchenkov

[m_emelchenkov]

With some help from "Rolo" user and looking at schematics from service manual I found out that 9th pin on both connectors (from Vectrex side) was broken. What a pity! I need a replacement for both connectors now. Are they standard? Can I buy it somewhere?

 

UPD: I see, it is standard DB9, and I hope someone know where to buy original plastic ones or just its pins.

Edited October 21, 2018 by m_emelchenkov

[mattsoft]

If you haven't already, start by replacing the integrator caps (https://console5.com/store/vectrex-integrator-cap-kit.html) they are the 5 styrene caps near the back right of the mainboard. They seem to cause the most display headaches.

[m_emelchenkov]

mattsoft, it will be the easiest way, if the caps cause the problems. I awaiting shipping of ESR meter to check capacitors first, and if any faulty, then order a replacement set. Right now I am looking for joystick sockets (http://atariage.com/forums/topic/284488-wtb-atari-like-db9-sockets/?do=findComment&comment=4145039), to be able to start Test cart program.