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VECTREX WITH PROBLEMS

Ok, so the power board electronics look fine to me. Can I suggest reattaching the heatsink to IC401, reinstalling everything back into the case and ensuring it still works as it did before you dismantled it!

We can have a look at the magnetics next. However, I have to do a couple of jobs first...

Yep, spaghetti carbonara and tiramisu. Unfortunately, I was one of the ‘designated drivers’, so no ‘vino’ for me... We had the alcohol free Peroni instead.

Dave
 
daver2 said:
Ok, so the power board electronics look fine to me. Can I suggest reattaching the heatsink to IC401, reinstalling everything back into the case and ensuring it still works as it did before you dismantled it!

We can have a look at the magnetics next. However, I have to do a couple of jobs first...

Yep, spaghetti carbonara and tiramisu. Unfortunately, I was one of the ‘designated drivers’, so no ‘vino’ for me... We had the alcohol free Peroni instead.

Dave
Click to expand...
I like carbonara ;) (egg and bacon like English Style) ;)
Ok i remount power board!
 
Ok power board in case and still works as it did before you dismantled it!
 
Dave, i'm now very scared! :(
Can be bad yoke???? In this case, Vectrex can't be repaired :(
 
Before we give up on the logic board and move on to the magnetics, I would like you to take a few measurements for me please.

You will need to perform these with your oscilloscope. Expect to see signals round about +5V and -5V. These should be digitals, so should switch from one voltage to the other fairly quickly.

Can you check for pulses on IC305 pins 5 and 6. These are controlled from the /RAMP signal.

Then can you check for pulses on IC305 pins 12 and 13. These are controlled from the /ZERO signal.

There are a few more measurements I will give you later.

Dave
 
daver2 said:
Before we give up on the logic board and move on to the magnetics, I would like you to take a few measurements for me please.

You will need to perform these with your oscilloscope. Expect to see signals round about +5V and -5V. These should be digitals, so should switch from one voltage to the other fairly quickly.

Can you check for pulses on IC305 pins 5 and 6. These are controlled from the /RAMP signal.

Then can you check for pulses on IC305 pins 12 and 13. These are controlled from the /ZERO signal.

There are a few more measurements I will give you later.

Dave
Click to expand...
Thanks Sir. Dave, do you need scope s' video or only pictures?
 
Ok, these are scope measure videos:
IC305:

PIN5:
PIN6:
PIN12:
PIN13:
 
Hmm,

They are rubbish!

IC305 pins 5 and 6 should be physically connected to the same signal - so they should look exactly the same on the oscilloscope traces. They don't.

Equally, IC305 pins 12 and 13 are also physically connected to the same signal - so they should also look exactly the same on the oscilloscope traces. There is a marked difference here! Especially pin 12 where there appears to be no signal at all..

You need to investigate around here...

Check (with the power OFF using your multimeter set to resistance) that there is a connection between IC305 pins 5 and 6 AND transistor Q301 collector.

Similarly, check that there is a connection between IC305 pins 12 and 13 AND transistor Q302 collector.

Is IC305 in an IC socket? If so, check the socket to IC pins for a good connection.

IC305 is a fairly common CMOS IC (CD4066B) so you could easily (and cheaply) replace it if it is in an IC socket.

IC305 pin 12 with no signal could well be the cause of your problems?

Go get it!

Dave
 
daver2 said:
Check (with the power OFF using your multimeter set to resistance) that there is a connection between IC305 pins 5 and 6 AND transistor Q301 collector.

Similarly, check that there is a connection between IC305 pins 12 and 13 AND transistor Q302 collector.
Click to expand...
Yes, i have continuity....

daver2 said:
s IC305 in an IC socket? If so, check the socket to IC pins for a good connection.

IC305 is a fairly common CMOS IC (CD4066B) so you could easily (and cheaply) replace it if it is in an IC socket.
Click to expand...
Ok i try to search this spare!! Thanks!
 
Good morning Dave! I forgot an important thing! I have another Vectrex that turns on but has a problem .... when you press any button on the joypad, it freezes and the screen disappears!
This other vectrex is however different ... it is not from MB but from GCE ... it seems to have been modified by the factory to operate at 220v. Instead of the plug it has a kind of transformer ....I would like to fix this too if possible but after this .... I thought we can swap some chips between the two consoles .... right? This is video of this GCE Vectrex:

 
I am not a lucky guy :(
Ic305 is not socketed on the two vectrex...
 
Last edited:
Another one!

Perhaps we could concentrate on why we are getting different readings on IC305 pins 5 and 6, and pins 12 and 13 when there are PCB tracks between them?

This shouldn’t happen.

Are you sure you are measuring on the correct pins of the correct IC first?

Dave
 
daver2 said:
Another one!

Perhaps we could concentrate on why we are getting different readings on IC305 pins 5 and 6, and pins 12 and 13 when there are PCB tracks between them?

This shouldn’t happen.

Are you sure you are measuring on the correct pins of the correct IC first?

Dave
Click to expand...
Ops....i
i was wrong ic ..... i measured on ic303 :(

Sorry....
i Repeat scope on correct ic now!!
 
Excellent, they look correct now we are measuring on the correct IC!

I will have a look for the next point to measure in a minute.

Did you order that Vectrex diagnostic cartridge?

Dave
 
daver2 said:
Excellent, they look correct now we are measuring on the correct IC!

I will have a look for the next point to measure in a minute.

Did you order that Vectrex diagnostic cartridge?

Dave
Click to expand...
Yes, i ordered pcb and when it comes, i'll create one... :)
 
Can we go back to monitoring (with the oscilloscope) IC303 pins 1 and 14 please. A video of each pin would be useful.

On your other vectrex, I would disconnect your hand controller from the main unit and check for any unintentional short circuits between any of the pins when you press the buttons. The hand controller only consists of two potentiometers and four normally-open pushbuttons. The schematic is in the maintenance manual.

I suspect a short circuit accidentally shorting +5V ANA or -5V ANA to GND when you press a button. Somewhere to start at least...

I wouldn’t use this hand controller until it has been tested out. Of course, if you have tried the vectrex with another hand controller (and it does the same thing) the fault is on the logic board not the hand controller.

Dave
 
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