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VECTREX WITH DESPERATION

Why the glum face. That accounts for why the -13V doesn't work - the circuitry is not being fed with a source of AC volts!

Right, so follow the RED wire back from point EP106. It should go to a switch (SW301). This should be the same for the RED wire from EP104 also.

The two wires from the transformer feed into this switch and the two red wires from the switch feed the power board.

We have two possible faults:

1. The transformer winding is faulty.
2. One of the internal poles of switch SW301 is faulty.

We need to ascertain which one...

Put your multimeter black probe on the white transformer wire at EP105. Set for AC volts.

Check ALL of the power leads (both from the transformer and to the power board) on switch SW301 with your multimeter's red probe.

10V AC is good. No voltage is bad.

I am a little confused as to why you were reading -5V on the logic board though if there is no AC voltage on EP106?

Dave
 
I am desperate because on the switch i have two pins with 3.5Vac, one pin with 10.2 VAC and one pin with 0.2 VAC
 

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You can't have - it is not physically possible! The laws of physics still have to stand...

If we measured 10V on RED1 after the switch - then that voltage has to come from somewhere (doesn't it?).

Clean up the outside of the switch (get rid of the fluff and everything else I can see that should not be there) and then clean up the blobs of solder to make sure that your multimeter probes make good contact.

Dave
 
Dave, i have 10,2 V on red1 to switch but i have 0,2 V on red2 to switch!
 
> Dave, i have 10,2 V on red1 to switch but i have 0,2 V on red2 to switch!

In this case it probably indicates that your transformer is faulty - or the switch is shorting out the transformer winding in some way.

You must have 10,2 V then on one of the red wires from the switch to the power board as a cross-check.

Dave
 
daver2 said:
You must have 10,2 V then on one of the red wires from the switch to the power board as a cross-check.
Click to expand...
I have 10,2 V on one of the red wires from the switch...but not in the other red from switch...
 
That's OK.

If you have volts going into the switch on one red wire, and the switch is working, then you should get volts coming out of the switch on the corresponding red wire.

If no volts are going in, then you won't get volts coming out.

This switch is 2-pole (hence it switches both red wires separately).

The next thing is to disconnect the red wire from the transformer to the switch that is NOT reading any voltage and check again (directly on the red wire from the transformer that has now been disconnected from the switch) to see if there are any volts or not now it has been disconnected from the switch.

If not, there is another test we can do to absolutely confirm that it is the transformer that is at fault...

Always check twice when you suspect you have found the fault!

Dave
 
daver2 said:
The next thing is to disconnect the red wire from the transformer to the switch that is NOT reading any voltage and check again (directly on the red wire from the transformer that has now been disconnected from the switch) to see if there are any volts or not now it has been disconnected from the switch.
Click to expand...
So must i desold red wire from witch, correct?
 
I desolded red2 wire from the switch...i measured this red2 wire coming from the power board and I still have 0.2 VAC...but im not sure if we are talking about the same wire :(
 
Is this correct wire?
 

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Well I didn't take the measurement in the first place - you did... So I have no idea if this is the correct wore or not do I?

Does this red wire that you have desoldered from the switch go to the transformer?

If so, have you measured from the free end of it to the white wire with your multimeter set to read AC volts?

As a cross-check, you could measure the voltage on the other red wire from the transformer (still soldered to the switch) and this should still be reading 10 Volts AC (relative to the white wire).

Dave
 
Desperado said:
ok ok i understand...time to white flag for this case :(
Click to expand...

For today or forever?

You are so close to finding the problem. You have just taken a wrong turn... Let's backup by a step and try again.

I was talking about the wires FROM the transformer TO the switch. Not anything else.

Solder the wire you have disconnected from the switch back to the switch and we will reconvene again tomorrow.

Are you following what we are doing on the schematic or not? if not, this is why you are getting lost...

Screenshot 2023-04-05 at 20.42.13.png
T101 is the transformer.

The WHITE wire is marked as C.T. and goes to the power board at terminal EP105.

The other two terminals from the transformer are the two RED wires (marked as PHI1 and PHI2). These go to the 2-pole switch (SW301) and then to the power board at terminals EP104 and EP106.

I am talking about the two RED wires PHI1 and PHI2 from the transformer to the switch.

Dave
 
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daver2 said:
For today or forever?

You are so close to finding the problem. You have just taken a wrong turn...

I was talking about the wires FROM the transformer TO the switch. Not anything else.

Solder the wire you have disconnected from the switch back to the switch and we will reconvene again tomorrow.

Are you following what we are doing on the schematic or not? if not, this is why you are getting lost...

Dave
Click to expand...
Ok thanks so much...i have 10,2 VAC from the two red wires FROM the transformer to switch...
 
I have also 10,2 VAC on red1 and red2 wires connected on power board...
 
Excellent. So the transformer is working OK!

So, I assume, you DO NOT have 10V from the other two terminals of the switch with it switched ON? Is this the case?

Dave
 
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