|
|
Post by dennis88 on Oct 28, 2015 3:12:31 GMT -5
For those who are struggling with the white dot problem, this was my fix. I bought a faulty vectrex which didn't start up.
symptoms:
- white dot slightly off center in the middle - no vectrex "buzz" - light bulb from tube is glowing - when touching the reset button the white dot moves - Brightness pot behind vectrex is responding - static and sometimes beeping sounds from speaker.
Solution:
- Checked voltages on the power board - 4.95 v, ground ,+ 4.88 v en -0.77 v ( aha! must be - 13v! ) - Checked voltages at the power switch ( 1 of the 2 didn't have voltage continuity ) - fixed the switch - Powered up the system and yes we have -13 v! , but still the white dot....... - Switched the removable ic's from the logic board ( i have a second and working vectrex ), IC chip SY6522 was faulty.
Hopefully this will help out some with the white dot problem 
With kind regards,
Dennis
|
|
|
|
Post by VectorX on Oct 28, 2015 10:41:04 GMT -5
Nice post. Quick question though: Solution:
- Checked voltages on the power board - 4.95 v, ground ,+ 4.88 v en -0.77 v ( aha! must be - 13v! ) - Checked voltages at the power switch ( 1 of the 2 didn't have voltage continuity ) - fixed the switch - Powered up the system and yes we have -13 v! , but still the white dot....... - Switched the removable ic's from the logic board ( i have a second and working vectrex ), IC chip SY6522 was faulty.
Are these all of the possible solutions to the "white dot" problem? If so, nice to have a guide on here. |
|
|
|
Post by dennis88 on Oct 28, 2015 11:14:21 GMT -5
In my case this was the solution. The white dot problem is a common problem and many parts can be faulty. Also good to mention:
- check the power and logic board for broken or bad solder points - Swollen or leaking capacitors - Clean the removable ic's and sockets and check for dust in sockets or corrosion (also check if they are firmly mounted ) - measure the 4 wire point on the power board - check the x-y-z cable for correct voltages/ resistance
I,m not an expert in fixing Vectrex systems but every fixed problem is good to mention for the community!
|
|
|
|
Post by VectorX on Oct 28, 2015 11:38:09 GMT -5
^Indeed, as I plan to sticky this thread.
Anyone else who can offer advice to this problem is welcome to add to it.
|
|
|
|
Post by scroeffie on Jan 15, 2016 3:58:42 GMT -5
my vectrex Brightness pot does not like to be turned ! it has a delay if i turn it
sometimes no image some super bright and there is a white dot in the middle not moving
lookes like a hole if i lower the brightness it wil go away
|
|
|
|
Post by scroeffie on Jan 15, 2016 4:03:13 GMT -5
maybe my pod needs cleaning how and with what ? other than that its works perfect
|
|
|
|
Post by sj on Jan 15, 2016 10:28:28 GMT -5
my vectrex Brightness pot does not like to be turned ! it has a delay if i turn it sometimes no image some super bright and there is a white dot in the middle not moving lookes like a hole if i lower the brightness it wil go away I think that behaviour is normal. Set the control so the dot just disappears. |
|
iesposta
Vector Runner
Spelunking VeCaves
Posts: 45 
|
Post by iesposta on Aug 7, 2016 5:06:22 GMT -5
My white dot fix was to replace IC401 under the giant heat sink.
My white dot vectrex had every issue listed above, except the sound (with buzz) and games played normal, just with a display of a white dot.
Medium to hard difficulty as you needed to desolder 16 (?) IC pins after removing the giant heat sink that is attached to IC401.
High watt iron to remove the wires soldered to the bottom of the power board so as to remove it from the console.
Low watt iron to remove IC401 without lifting circuit board traces.
Notes: IC401 is used in Q*Bert. In the Vextrex it is used for vector beam deflection (I think?).
Getting it perfectly adjusted without an oscilloscope is not going well. Games that don't draw out past the bezel edge are fine, games that push the limits have vectors not aligning out at the edges - that could also mean another part is failing, but most electrolytic caps have been replaced, and also the 6 odd caps (tantalum?) around the 2 pot wheel adjustments on the CPU board where the X Y Z wires connect, and some other components.
It also seems that the white dot is sometimes the sound chip, sometimes the CPU chip, sometimes it is the on/off volume, and even as simple as reseating the socketed chips.
Guess mine was the hardest to fix, but that small part must be pushed hard to have such a gigantic heat sink, and is not hard to believe it failed from overheating anyway.
|
|
|
|
Post by coleco1981 on Oct 17, 2016 21:31:16 GMT -5
Thanks for posting this up. I recently attended the RetroWorld gaming Expo in Wallingford, CT this last weekend and I purchased 2 non-working vectrex units. I got them for a bargain of course.
The first unit was an easy fix. It had vertical collapse - I reseated the socketed chips and the connecting cables to the logic board. That resolved the issue.
The second unit had the white dot problem no sound. I checked the voltages going into the logic board and they were all OK. I also found that the SY6522 Versatile Interface Adapter chip went bad.
I'm trying to find a replacement SY6522 to purchase and its not clear if a newer version of the chip will be OK to use? My understanding is that the interrupts are handled differently in the updated version (made by WDC). At any rate I'm in search of a replacement to order at a reasonable price - anyone have a suggestion?
Thanks!
|
|
|
|
Post by kokovec on Oct 18, 2016 0:40:02 GMT -5
You can always try Ebay VIA |
|
|
|
Post by coleco1981 on Oct 18, 2016 22:48:38 GMT -5
Yep saw that $20 plus $6 shipping? The new variation of this chip is so much cheaper..does anyone know of if they will work?
|
|
|
|
Post by David on Jan 28, 2017 15:19:46 GMT -5
Hi there, had one of these to fix a mate and I had a real battle. Very first thing you need to do is to turn down the brightness as this fault can wreck the tube. The vectrex does have a protection circuit that will protect the tube if there are no X or Y signals by cutting the brightness. Checked the AC from the switch, was ok. Checked power to logic board (+\- 5v and -13v), was all ok. Got the osciloscope out and then checked the X and Y signals and found that these were giving nothing. Checked the out put of the DAC, nothing, checked the digital input to the DAC and found that data lines 0-7 were all static. Check the cpu xtal all ok the E clock was also good could be the SY6522 but this seemed OK in another working vectrex. Also pulled the AY sound chip and still no action. In the end after a few hours of trouble shooting I had a faulty ram chip fortunately I had a spare 2116 in my collection of ICs. I do have DMM, oscilloscope and a through hole desoldering tool would not have been possible to repair otherwise.
|
|
|
|
Post by gauze on Jan 28, 2017 17:14:36 GMT -5
Yep saw that $20 plus $6 shipping? The new variation of this chip is so much cheaper..does anyone know of if they will work? I think any 6522 DIP40 will work, Malban tested all these pictured in his blog post and said they all work: vide.malban.de/in-via-we-trust |
|
