On Thursday, September 1, 2011 at 6:35:59 AM UTC+10, uncle...@jerk.org wrote:

I am trying to repair a friend's vectrex that is dead as a doornail,
except for a white dot, is there any source for 68A09 CPU (not bob
roberts) or is there another replacement I can use it it's place
(assume 1mhz 6809 is too slow, 2mhz 68B09, would it need a different
clock crystal (what value?)

anything else to watch out for?

thanks

Hello There

I am very interested to know if you ever fixed this? I have the same problem and I am very keen to repair it. I have a good quality scope and decent electronics knowledge. I was reading through this conversation and you were all very helpful and
knowledgeable, wondering if I could get some help if any of you are around.

Regards
Brad

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bradley.fechner@gmail.com wrote:

On Thursday, September 1, 2011 at 6:35:59 AM UTC+10, uncle...@jerk.org wrote:

I am trying to repair a friend's vectrex that is dead as a doornail,
except for a white dot, is there any source for 68A09 CPU (not bob
roberts) or is there another replacement I can use it it's place
(assume 1mhz 6809 is too slow, 2mhz 68B09, would it need a different
clock crystal (what value?)

anything else to watch out for?

thanks

Hello There

I am very interested to know if you ever fixed this? I have the same
problem and I am very keen to repair it. I have a good quality scope
and decent electronics knowledge. I was reading through this
conversation and you were all very helpful and knowledgeable,
wondering if I could get some help if any of you are around.

There are a lot of potential causes, it means that the Logic board
circuitry isn't generating a picture signal - which is the key
purpose for most of it, so there's a lot that could go wrong. Unless
you already have reason to already suspect the 68A09, I would begin
by checking the power supply voltages on the logic board.

If the sound works, then it's likely a problem in the area of the
circuitry that generates the final picture signals for the CRT,
rather than the CPU and processing circuitry.

There are some notes here on the Vector Gaming Forums: http://vectorgaming.proboards.com/thread/1469/vectrex-white-dot-problem-fixed

In case you haven't already got it: http://computernerdkev.heliohost.org/vecadapt/Vectrex_service_manual.pdf

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On Sunday, April 2, 2017 at 10:48:21 AM UTC+10, Computer Nerd Kev wrote:

bradley.fechner@gmail.com wrote:

On Thursday, September 1, 2011 at 6:35:59 AM UTC+10, uncle...@jerk.org wrote:

I am trying to repair a friend's vectrex that is dead as a doornail,
except for a white dot, is there any source for 68A09 CPU (not bob
roberts) or is there another replacement I can use it it's place
(assume 1mhz 6809 is too slow, 2mhz 68B09, would it need a different
clock crystal (what value?)

anything else to watch out for?

thanks

Hello There

I am very interested to know if you ever fixed this? I have the same problem and I am very keen to repair it. I have a good quality scope
and decent electronics knowledge. I was reading through this
conversation and you were all very helpful and knowledgeable,
wondering if I could get some help if any of you are around.

There are a lot of potential causes, it means that the Logic board
circuitry isn't generating a picture signal - which is the key
purpose for most of it, so there's a lot that could go wrong. Unless
you already have reason to already suspect the 68A09, I would begin
by checking the power supply voltages on the logic board.

If the sound works, then it's likely a problem in the area of the
circuitry that generates the final picture signals for the CRT,
rather than the CPU and processing circuitry.

There are some notes here on the Vector Gaming Forums: http://vectorgaming.proboards.com/thread/1469/vectrex-white-dot-problem-fixed

In case you haven't already got it: http://computernerdkev.heliohost.org/vecadapt/Vectrex_service_manual.pdf

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Thankyou for your quick response, looks like I have found the right place to find some help.

Thankyou for that Forum link, I have done a lot of internet searching and had not found that one, with the testing I have done I feel the problem had to be a chip between the cart connector and Sound/ I/O Chip. In this discussion two people with
identical symptoms found the 6522A VIA to be at fault, So it looks like I might need to get one of these unless I can do further testing to see if its at fault?

Here is the testing I have done so far:

*CRT displays white dot and no sound when first turned on. However my fault has an interesting twist, when wriggling a cart in the cart slot and pressing reset many times I can get the white dot to move, with enough patience perhaps after 15 mins of
doing this, It boots! shows startup screen and sound will work.

*However first time I did this the sound was slow and the buttons on the controller did not work, so via the schematic I was confident this was the sound chip, so I replaced it and when it booted again after tirelessly wriggling a cart and pressing reset
the sound and controller problems were fixed.

This is not the only problems I have, when I can get it to boot, the vectored image is very muddled, Here is a video I posted to Youtube before I replaced the sound chip:

https://www.youtube.com/watch?v=iwjD1T6spz4

*I cant stress enough that it isn't easy to get it to boot, and I believe anyone with the white dot no sound problem may also be able to get it to boot by wriggling a cart and resetting but haven't had the patience :)


I however believe the screen issue is a separate fault in the analogue section IC's or could also be integrator caps?

I have done lots of other testing, power supply voltages was the first thing I checked and these were all good on both boards.

One interesting thing I would like to note is when it is showing white dot no sound the bus between the VIA and DAC is all 5V, This proves to me that nothing is driving the DAC so any of the chips between the Cart connector slot and Sound I/O Chip are
probably at fault?

Let me know what you think.

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On Sunday, April 2, 2017 at 12:52:15 AM UTC-7, Bradley Fechner wrote:

On Sunday, April 2, 2017 at 10:48:21 AM UTC+10, Computer Nerd Kev wrote:

bradley.fechner@gmail.com wrote:

On Thursday, September 1, 2011 at 6:35:59 AM UTC+10, uncle...@jerk.org wrote:

I am trying to repair a friend's vectrex that is dead as a doornail,
except for a white dot, is there any source for 68A09 CPU (not bob
roberts) or is there another replacement I can use it it's place
(assume 1mhz 6809 is too slow, 2mhz 68B09, would it need a different
clock crystal (what value?)

anything else to watch out for?

thanks

Hello There

I am very interested to know if you ever fixed this? I have the same problem and I am very keen to repair it. I have a good quality scope
and decent electronics knowledge. I was reading through this
conversation and you were all very helpful and knowledgeable,
wondering if I could get some help if any of you are around.

There are a lot of potential causes, it means that the Logic board circuitry isn't generating a picture signal - which is the key
purpose for most of it, so there's a lot that could go wrong. Unless
you already have reason to already suspect the 68A09, I would begin
by checking the power supply voltages on the logic board.

If the sound works, then it's likely a problem in the area of the
circuitry that generates the final picture signals for the CRT,
rather than the CPU and processing circuitry.

There are some notes here on the Vector Gaming Forums: http://vectorgaming.proboards.com/thread/1469/vectrex-white-dot-problem-fixed

In case you haven't already got it: http://computernerdkev.heliohost.org/vecadapt/Vectrex_service_manual.pdf

--
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#_ < |\| |< _#

Thankyou for your quick response, looks like I have found the right place to find some help.

Thankyou for that Forum link, I have done a lot of internet searching and had not found that one, with the testing I have done I feel the problem had to be a chip between the cart connector and Sound/ I/O Chip. In this discussion two people with

identical symptoms found the 6522A VIA to be at fault, So it looks like I might need to get one of these unless I can do further testing to see if its at fault?

Here is the testing I have done so far:

*CRT displays white dot and no sound when first turned on. However my fault has an interesting twist, when wriggling a cart in the cart slot and pressing reset many times I can get the white dot to move, with enough patience perhaps after 15 mins of

doing this, It boots! shows startup screen and sound will work.

*However first time I did this the sound was slow and the buttons on the controller did not work, so via the schematic I was confident this was the sound chip, so I replaced it and when it booted again after tirelessly wriggling a cart and pressing

reset the sound and controller problems were fixed.

This is not the only problems I have, when I can get it to boot, the vectored image is very muddled, Here is a video I posted to Youtube before I replaced the sound chip:

https://www.youtube.com/watch?v=iwjD1T6spz4

*I cant stress enough that it isn't easy to get it to boot, and I believe anyone with the white dot no sound problem may also be able to get it to boot by wriggling a cart and resetting but haven't had the patience :)

I however believe the screen issue is a separate fault in the analogue section IC's or could also be integrator caps?

I have done lots of other testing, power supply voltages was the first thing I checked and these were all good on both boards.

One interesting thing I would like to note is when it is showing white dot no sound the bus between the VIA and DAC is all 5V, This proves to me that nothing is driving the DAC so any of the chips between the Cart connector slot and Sound I/O Chip are

probably at fault?

Let me know what you think.

Hi Bradley,

I sounds like the bad old capacitor rot. Vectrex are known for having this problem.

The first clue is the 15 minute boot. The multiple reboots are minimally reforming the capacitor's in the power supply so that the ac ripple is below the threshold where the CPU can actually boot. If you use your o-scope on the power rails you will see
that they are off voltage (likely) and have a lot of noise on the rails. Use the service manual above to find the test points.

A good second clue is that when the machine does boot up the sound is fine. Or at least plays. This could not happen if the CPU and all the main chips around it were not working. So you can skip looking for new chips.

Thirdly lets look at your video, specifically when the gunship is zooming into the play field. You can clearly see the vectors being drawn, but none of them are closing the loop to correctly draw the ship. The vectrex uses the R/C time constant of the
capacitor charge to draw the correct slope of the line from any point to some other point. So if your caps are dried up and failing, or your voltages are not stable, your time constant has gotten all screwed up and nothing on the screen will ever be
right. You could try the alignment process and use the test cart, but it will never be right with the caps shot.

Doing a quick search turns up a site that has a cap kit for sale. https://console5.com/store/vectrex-cap-kit.html
They have a link on this page for the integrator cap kit as well. https://console5.com/store/vectrex-integrator-cap-kit.html

Good idea to do these while you have everything torn apart. You will need to do the alignment once everything has been replaced.

Their Wiki has some nice work and data for you on the replacement locations. I have no experence with this company so good luck and do further searches for more cap information.

-Cecil

--- SoupGate-Win32 v1.05
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bradley.fechner@gmail.com wrote:

Thankyou for your quick response, looks like I have found the right place
to find some help.

Thankyou for that Forum link, I have done a lot of internet searching and
had not found that one, with the testing I have done I feel the problem
had to be a chip between the cart connector and Sound/ I/O Chip. In this discussion two people with identical symptoms found the 6522A VIA to be
at fault, So it looks like I might need to get one of these unless I
can do further testing to see if its at fault?

As already suggested, you might want to check for power supply ripple
using your oscilloscope, if it's a few hundred millivolts, that could
be the problem. Perhaps the ripple settles down after a time as described already, and resetting the system after that point allows it to work.

Here is the testing I have done so far:

*CRT displays white dot and no sound when first turned on. However my
fault has an interesting twist, when wriggling a cart in the cart slot
and pressing reset many times I can get the white dot to move, with
enough patience perhaps after 15 mins of doing this, It boots! shows
startup screen and sound will work.

*However first time I did this the sound was slow and the buttons on
the controller did not work, so via the schematic I was confident this
was the sound chip, so I replaced it and when it booted again after tirelessly wriggling a cart and pressing reset the sound and controller problems were fixed.

The sound chip may have been damaged by excessive voltage from the power supply, though this would suggest the voltage regulator ICs at fault
rather than the power supply capacitors. These can also cause ripple
when fail, although more in the form of intermittent voltage spikes.

This is not the only problems I have, when I can get it to boot, the
vectored image is very muddled, Here is a video I posted to Youtube
before I replaced the sound chip:

https://www.youtube.com/watch?v=iwjD1T6spz4

*I cant stress enough that it isn't easy to get it to boot, and I
believe anyone with the white dot no sound problem may also be able
to get it to boot by wriggling a cart and resetting but haven't had
the patience :)

I however believe the screen issue is a separate fault in the analogue section IC's or could also be integrator caps?

I'll look at the video later, but from the description in the other
post, the capacitors there do seem most likely at fault.

I have done lots of other testing, power supply voltages was the first
thing I checked and these were all good on both boards.

One interesting thing I would like to note is when it is showing white
dot no sound the bus between the VIA and DAC is all 5V, This proves to
me that nothing is driving the DAC so any of the chips between the Cart connector slot and Sound I/O Chip are probably at fault?

Let me know what you think.

Have you had a close look at the capacitors to see whether any are
bulging, leaking, or emitting a bad smell? They can fail without doing
this though.

If you're confident of the power supply, then a logic chip is indeed
most likely still at fault. However the loss of more than one logic
chip suggests in itself a power supply issue.

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--- SoupGate-Win32 v1.05
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On Thursday, September 1, 2011 at 6:35:59 AM UTC+10, uncle...@jerk.org wrote:

I am trying to repair a friend's vectrex that is dead as a doornail,
except for a white dot, is there any source for 68A09 CPU (not bob
roberts) or is there another replacement I can use it it's place
(assume 1mhz 6809 is too slow, 2mhz 68B09, would it need a different
clock crystal (what value?)

anything else to watch out for?

thanks

Thankyou both for your reply's

I think the voltages are alright, there is little to no noise on the 5V lines, a bit more on the 13v line, a 100mv saw shaped ripple, but when I was able to boot the Vectrex, this ripple did not change.

There is definitely no visible problems with any of the electrolytic caps, this was the very first thing I looked for when I opened it up. I worked as an apprentice for while at an AV workshop, Bulging caps were the first things they looked at every time
opening a tv :)

I don't want to rule out caps, as I know they quite possibly could be bad, but would like to be more certain if possible before I buy them, I would have to round them up as the kit would be to expensive to have posted from the US.

Any other ideas? I am tempted to buy a 6522A Via IC, seeing this was faulty in two similar cases.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Bradley Fechner <bradley.fechner@gmail.com> wrote:

On Thursday, September 1, 2011 at 6:35:59 AM UTC+10, uncle...@jerk.org wrote:

I am trying to repair a friend's vectrex that is dead as a doornail,
except for a white dot, is there any source for 68A09 CPU (not bob
roberts) or is there another replacement I can use it it's place
(assume 1mhz 6809 is too slow, 2mhz 68B09, would it need a different
clock crystal (what value?)

anything else to watch out for?

thanks

Thankyou both for your reply's

I think the voltages are alright, there is little to no noise on the
5V lines, a bit more on the 13v line, a 100mv saw shaped ripple, but
when I was able to boot the Vectrex, this ripple did not change.

There is definitely no visible problems with any of the electrolytic
caps, this was the very first thing I looked for when I opened it up.
I worked as an apprentice for while at an AV workshop, Bulging caps
were the first things they looked at every time opening a tv :)

I don't want to rule out caps, as I know they quite possibly could
be bad, but would like to be more certain if possible before I buy
them, I would have to round them up as the kit would be to expensive
to have posted from the US.

Any other ideas? I am tempted to buy a 6522A Via IC, seeing this was
faulty in two similar cases.

One other possibility might be that there's a dry solder joint on the
board and your wriggling of the cartridge in the slot causes the board
to flex and the joint to make contact again. You'd want to inspect the
joints on the board visually and reflow any that look like they might
not be properly bonding with the component pins, feeding in some new
solder at the same time.

If the logic board components themselves are the only suspects left,
the only way to confirm a particular failure short of swapping chips
would be to analyse the signals on the board from when boots. So
you'd want to check that the CPU was toggling its address lines, the
ROM was sending data back, the I/O chips were receiving/sending I/O,
etc. You'd ideally want a logic analyser that could capture and
display all the signals at once. A possible poor-man's alternative
could be to rig the CPU clock up so that it can be manually advanced,
then step through the boot-up routine checking all the chip inputs
and outputs one by one using a logic probe, oscilloscope, or
multimeter.

You might find the chip swapping approach easier.

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On Monday, April 3, 2017 at 5:25:03 AM UTC-7, Bradley Fechner wrote:

On Thursday, September 1, 2011 at 6:35:59 AM UTC+10, uncle...@jerk.org wrote:

I am trying to repair a friend's vectrex that is dead as a doornail,
except for a white dot, is there any source for 68A09 CPU (not bob
roberts) or is there another replacement I can use it it's place
(assume 1mhz 6809 is too slow, 2mhz 68B09, would it need a different
clock crystal (what value?)

anything else to watch out for?

thanks

Thankyou both for your reply's

I think the voltages are alright, there is little to no noise on the 5V lines, a bit more on the 13v line, a 100mv saw shaped ripple, but when I was able to boot the Vectrex, this ripple did not change.

There is definitely no visible problems with any of the electrolytic caps, this was the very first thing I looked for when I opened it up. I worked as an apprentice for while at an AV workshop, Bulging caps were the first things they looked at every

time opening a tv :)

I don't want to rule out caps, as I know they quite possibly could be bad, but would like to be more certain if possible before I buy them, I would have to round them up as the kit would be to expensive to have posted from the US.

Any other ideas? I am tempted to buy a 6522A Via IC, seeing this was faulty in two similar cases.

Sorry, I guess I messed up, the caps on the Vectrex do not swell or bulge like cheep modern caps, they dry out and loose the means to store a charge. A tube of toilet paper has as good a capacitance value once that happens. ESR goes to heck, and
filtering drops off. Like I said it is a common vectrex issue, check any old vectrex archive to find many issues just like yours.

Your machine can boot, it can draw, it can make music. It's not the chips. It is only the chips when you never get anything in one of those classes.

If you want to know for sure plug in a controller and start the game once it boots, even if you can't see it does it start? If it can then the PIA is fine, but then sounds and drawing would not work with out the PIA either.

Do both cap kits and the alignment before you mess with the IC chips.

-C

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On Wednesday, April 5, 2017 at 12:45:56 AM UTC+10, Cecil Casey wrote:

On Monday, April 3, 2017 at 5:25:03 AM UTC-7, Bradley Fechner wrote:

On Thursday, September 1, 2011 at 6:35:59 AM UTC+10, uncle...@jerk.org wrote:

I am trying to repair a friend's vectrex that is dead as a doornail, except for a white dot, is there any source for 68A09 CPU (not bob roberts) or is there another replacement I can use it it's place
(assume 1mhz 6809 is too slow, 2mhz 68B09, would it need a different clock crystal (what value?)

anything else to watch out for?

thanks

Thankyou both for your reply's

I think the voltages are alright, there is little to no noise on the 5V lines, a bit more on the 13v line, a 100mv saw shaped ripple, but when I was able to boot the Vectrex, this ripple did not change.

There is definitely no visible problems with any of the electrolytic caps, this was the very first thing I looked for when I opened it up. I worked as an apprentice for while at an AV workshop, Bulging caps were the first things they looked at every

time opening a tv :)

I don't want to rule out caps, as I know they quite possibly could be bad, but would like to be more certain if possible before I buy them, I would have to round them up as the kit would be to expensive to have posted from the US.

Any other ideas? I am tempted to buy a 6522A Via IC, seeing this was faulty in two similar cases.

Sorry, I guess I messed up, the caps on the Vectrex do not swell or bulge like cheep modern caps, they dry out and loose the means to store a charge. A tube of toilet paper has as good a capacitance value once that happens. ESR goes to heck, and

filtering drops off. Like I said it is a common vectrex issue, check any old vectrex archive to find many issues just like yours.

Your machine can boot, it can draw, it can make music. It's not the chips. It is only the chips when you never get anything in one of those classes.

If you want to know for sure plug in a controller and start the game once it boots, even if you can't see it does it start? If it can then the PIA is fine, but then sounds and drawing would not work with out the PIA either.

Do both cap kits and the alignment before you mess with the IC chips.

-C

Hello Cecil

I understand your absolutely right, I know electrolytic caps are notorious for going out of tolerance with age. So I know they could still be at fault, however at the same time I am also not disregarding chips as they still can be at fault aswell, the
sound chip was bad, but it was still able to create sound.

Something I would like to clear up with my fault, when I get it to boot, its only that time, as soon as I press reset its straight back to a white dot, no sound...dead and its just as hard to get it to start again. When I wriggle a card in the slot it
makes the dot move in what I would call a holding pattern, as if it freezes, sometimes I can make out dashed lines in the squiggles as if it has attempted starting the vectrex welcome screen and froze.


Some Further things I have done:

*Replaced all electrolytic caps on the logic board with spares I have on hand

*I moved Integrator caps around, (If only one was bad, maybe the screen issue would change) Which it did, the screen is now almost back to the way it should be.

* Re-flowed new solder on ALL the points on the logic board, I thought I should do this while I had the logic board out... again, thanks Computer Nerd Kev


Hello Computer Nerd Kev
Thats a very interesting idea, to step the CPU and observe the I/O's, not as easy as simply swaping chips, but would be cheaper and a fun interesting test. I built a simple computer from an old book made from 60 TTL chips that has the ability to step the
cpu like this. I might give it some thought

Brad

--- SoupGate-Win32 v1.05
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Bradley Fechner <bradley.fechner@gmail.com> wrote:

Hello Cecil

I understand your absolutely right, I know electrolytic caps
are notorious for going out of tolerance with age. So I know
they could still be at fault, however at the same time I am
also not disregarding chips as they still can be at fault
aswell, the sound chip was bad, but it was still able to
create sound.

Something I would like to clear up with my fault, when I get
it to boot, its only that time, as soon as I press reset
its straight back to a white dot, no sound...dead and its
just as hard to get it to start again. When I wriggle a card
in the slot it makes the dot move in what I would call a holding
pattern, as if it freezes, sometimes I can make out dashed lines
in the squiggles as if it has attempted starting the vectrex
welcome screen and froze.

Seems more likely a fault with the ROM or CPU causing the CPU to
lock up, as the I/O is apparantly doing its job in that situation.

Maybe wriggling the cartridge and thereby varying the load on the
data and address lines is causing either a ROM (Data) or CPU
(address) output to start to come back to life. Or it might be
the load on the 5V power line being connected and disconnected
with the ROM IC in the cartridge. Just guesses.

Some Further things I have done:

*Replaced all electrolytic caps on the logic board with spares
I have on hand

*I moved Integrator caps around, (If only one was bad, maybe
the screen issue would change) Which it did, the screen is
now almost back to the way it should be.

That's good news.

* Re-flowed new solder on ALL the points on the logic board,
I thought I should do this while I had the logic board out...
again, thanks Computer Nerd Kev

Hello Computer Nerd Kev
Thats a very interesting idea, to step the CPU and observe the
I/O's, not as easy as simply swaping chips, but would be cheaper
and a fun interesting test. I built a simple computer from an
old book made from 60 TTL chips that has the ability to step
the cpu like this. I might give it some thought

Impressive. For this you'd only need a simple debouncing circuit
on a push button. Ahh, I just checked the 6809 datasheet and it
states a minimum clock frequency of 400KHz. Perhaps still worth
trying, some other CPU designs are specified to operate at such
low frequencies (then again, you might not know what to blame
if there's a visible problem). Pin 38 (EXTAL) is connected to
the external clock signal, while pin 39 (XTAL) is connected
to ground according to the datasheet.

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