Strange behaviour of a 5151 Monitor.

[fjk61011]

Did you change the colour/mono switch? http://minuszerodegrees.net/5150/mis...h_settings.htm

Not sure if that would prevent a boot display though.

PM sent on the other item.

Doh! That could be the problem. I'll check later.

I used the MDA card that was working on the first 5150 and the switches in the second 5150 set for MDA card. No luck.

[modem7]

I used the MDA card that was working on the first 5150 and the switches in the second 5150 set for MDA card. No luck.

With the motherboard switches of the second 5150 set for MDA, if you remove the MDA card then power on the 5150, you should hear a series of beeps (1 long, 2 short) from the speaker.
That is the motherboard POST indicating that it cannot find an MDA card to initialise.
Do you hear that ?

[fjk61011]

With the motherboard switches of the second 5150 set for MDA, if you remove the MDA card then power on the 5150, you should hear a series of beeps (1 long, 2 short) from the speaker.
That is the motherboard POST indicating that it cannot find an MDA card to initialise.
Do you hear that ?

Tried that. beep 1 long 2short. Also tried MDA card with a NEC Multisynch which works.

Think Stone might be onto something.

[modem7]

Also tried MDA card with a NEC Multisynch which works.

On the second 5150 ?

[fjk61011]

On the second 5150 ?

Yes indeedy.

Using paul's method to change the 5151 to 220VAC input for the second 5150's 220v pass through.

[modem7]

Do you know if your stepdown transformer connects though the ground connection ?

[fjk61011]

Do you know if your stepdown transformer connects though the ground connection ?

Don't know.

[modem7]

Don't know.

I was just curious, because the only scenario that I can come up with that might explain the symptom is:
* Step-down transformer isolates ground; and
* Loss of ground in the 5151's video cable (or where it connects to within the 5151).

Seems unlikely, because in the 5151's video cable, two wires/pins carry the ground connection.

[fjk61011]

I was just curious, because the only scenario that I can come up with that might explain the symptom is:
* Step-down transformer isolates ground; and
* Loss of ground in the 5151's video cable (or where it connects to within the 5151).

Seems unlikely, because in the 5151's video cable, two wires/pins carry the ground connection.

I've started to convert the 5151 to 220Vac. Have removed the transformer, the voltage regulator and some class of a chip with three leg as per paul's instructions. Then my soldering Iron gave up the ghost before I could connect wires for the+ and - DC voltage.

[Chuck(G)]

Wouldn't it have been easier to use a step-down transformer?