Vectrex - replaced main transformer but no video/vector - need help.

[Braqoon]

Hi All,

 

I'm hoping for some help as I'm stuck. So I got a Vectrex that came to me dead (does not power on). After short diagnostic it turns out that main transformer was dead and i have replaced it with AC 9v-0-9v 1A (it is smaller than original in size).

To my joy, Vectrex came back to live and game was on. After about 5 minutes vectors got scrambled and screen went off (screaming Nooooo internally). Console still turns on and still plays controls & sound are working. I have not left console on for more than 5 min continuously and i have not seen any white dot appearing.

 

I have started googling to check what's wrong. Going with Troubleshooting Guide and this blog http://int03.co.uk/blog/2016/01/31/vectrex-repair-black-screen-no-vector/,I have checked -13V on power board but that is not the case. That power circuit is just fine. Going forward on J204 i got -4.96V, GND, 5.02V, -12.99V so that's within range.

 

Power input to power board on EP106 and EP104 is 10VAC which i thought is too high but on this forum http://vectorgaming.proboards.com/thread/1021/tech-repairing-vectrex-monitor, jasonbar have original transformer with higher than 8.6VAC, again i think that's OK.

 

Last thing in torubleshooting guide is to check T401 and T503. Not sure which those actually are. I think those are hidden in the small metal box on the power board, does anybody had problem with those ? how to check them. Also i should check for voltage on CRT PCB pins 2,3,5 and 6 (socket for the lamp?). Is CRT PCB one that is attached to the tube ? If so should i use ground on power board for test ? Can i disconnect that board from tube for test measurements ?

 

Lastly i know that somebody will tell me to do re-cap on power board but again, caps are Jamicon ones and those i have checked are in great condition. Visually non of them show any sings of leak or bloating on top. I would expect at least white dot on screen if some caps are bad. I did not removed caps form the board for check but most of them can be checked in board and readings are good. Non where below the stated value but slightly above. Those who are chained obviously is hard to check without taking them out but general trend is that caps are fine in my opinion. If i have to i will replace them but would prefer to understand the fault and not just blindly replace all caps.

 

Help will be highly appreciated. I'm a hobbyist and keen to get this working.

 

Thanks.