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VECTREX WITH PROBLEMS

Thanks Dave, this is scope on Ic303:

pin1:

pin14:

I just try this controller on the other Vectrex ma i have same trouble...when i press a key or i move stick...i see freeze on screen :(
 
The two pins look radically different (from a voltage swing perspective). But why I don’t know. It could be the op amp (IC303), it could be the analogue switch (IC305), or the integrating capacitor (C313).

However, we are using the game to look at the signals - so we really don’t know what should be there and what shouldn’t!

This is why we need the diagnostic cartridge. The cross hatch screen display should match the oscilloscope traces in the maintenance manual.

I propose, therefore, to wait until you get the diagnostic cartridge.

Dave
 
With regard to your other vectrex, there are two game ports. Does the same thing happen with the controller plugged into the second games port?

Is IC208 in a socket?

Dave
 
daver2 said:
With regard to your other vectrex, there are two game ports. Does the same thing happen with the controller plugged into the second games port?

Is IC208 in a socket?

Dave
Click to expand...
Ok!
For the other Vectrex....if i plug controller in the other port, nothing happens.....if i press any button or i move stick it's like to have controller disconnected. Ic208 is in a socket!
 
Plug the vectrex controller into the port that is causing the problem, and monitor the individual power rails at the following points whilst operating the controller buttons:

IC303 pin 4 +5V ANA.
IC303 pin 11 -5V ANA.
IC202 pin 14 +5V DIG.

If any voltage doesn’t indicate correctly when a button is pressed, look for a low resistance (or a short circuit) on the PCB from the games controller connector to the power rail in question.

The controller buttons should be wired (via 680 Ohm resistors) to the pins of IC208. Check out the schematic in the maintenance manual.

Of course, the other fault scenario is a bit-rotted ROM...

Dave
 
daver2 said:
Plug the vectrex controller into the port that is causing the problem, and monitor the individual power rails at the following points whilst operating the controller buttons:

IC303 pin 4 +5V ANA.
IC303 pin 11 -5V ANA.
IC202 pin 14 +5V DIG.
Click to expand...
ok voltages are correct also when i press any button
 
If you remove IC208 does it still do it?

You won’t get any audio output from the vectrex (IC208 is the sound generator). It is also just possible that the game won’t run either if the ROM is expecting some feedback from the PSG (that we have just removed).

Again, this is where the diagnostic cartridge comes into play as it checksums the ROM to see if there is any corruption...

Diagnostics are everything!

Dave
 
If i remove IC208 i can't hear any sounds and buttons don't works...i can rotate only spaceboat with stick.
I tryied to exchange this ic with that of the other Vectrex and i have same problems :(
 
That’s exactly what I said in post #107!

What I wanted to know is that with IC208 removed, does the video sub-system shut down or not when you operate the buttons?

IC208 is the sound generator and the input port for the buttons. No IC208 plugged in = no sound or button control!

If there was a short circuit on the PCB, then the problem would still exist is if IC208 was removed.

I didn’t want you to replace it either. I am not expecting that the IC is faulty. I just wanted to observe what happens when it is removed...

Dave
 
daver2 said:
What I wanted to know is that with IC208 removed, does the video sub-system shut down or not when you operate the buttons?
Click to expand...
with ic208 removed, the video sub system don't shut down but i can operate on the buttos because they don't works :)
 
I suspect a faulty ROM on this one (bit rotted).

That would be my first guess.

Put IC208 back and wait for the diagnostic cartridge to arrive.

Dave
 
just for information ..... this vectrex emits a much louder buzz than the other vectrex ...
 
ok Dave we waiting for the pcb and after i can make (i hope) test cart!!
Thanks so much!
 
Sir Dave, when the cartridge arrives, can you continue to help me to repair these two vectrex please? As I already told you, if you write me the address in private, I will be happy to send you a couple of bottles of Italian wine;)
 
>>> When the cartridge arrives, can you continue to help me to repair these two vectrex please?

Of course!

I might take you up on your kind offer presently. Let’s see if we can get some sense out of the diagnostic cartridge shall we?

Dave
 
daver2 said:
>>> When the cartridge arrives, can you continue to help me to repair these two vectrex please?

Of course!

I might take you up on your kind offer presently. Let’s see if we can get some sense out of the diagnostic cartridge shall we?

Dave
Click to expand...
Ok! When you want, write me your address :)
I update post when i have diagnostic cart in my hands :)
Bye!
 
It’ll arrive shortly. Have patience!

I am waiting for some Cromemco cards to arrive. They are in the UK now though...

Dave
 
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