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fjk61011
May 17th, 2017, 11:59 AM
I have two 5150s.

One is a 120V input fed from a 220V to 120V stepdown transformer. The 5151 Monitor is powered from the 5150 power supply auxiliary. The 5151 works in this setup.

However, using the other 5150 with a 220V input psu and the monitor powered directly from the 120V of the transformer, the monitor doesn't work.

Any ideas?

Stone
May 17th, 2017, 12:12 PM
Did you try the monitor that doesn't work with the system where the monitor does work?

fjk61011
May 17th, 2017, 12:17 PM
Did you try the monitor that doesn't work with the system where the monitor does work?

One monitor, two 5150s.

Stone
May 17th, 2017, 12:33 PM
The 5151 only 'works' when both the AC and video card are both functional. It's possible that using the external power source doesn't satisfy the circuitry requirements of 'the both'.

paul
May 17th, 2017, 12:49 PM
Are you sure the second 5150 has a suitable MDA/Hercules output and is not CGA?

The 5151 should work fine off the stepdown transformer as long as it's large enough to handle the load, about 100 VA.

I have two 5150 with 5151 units in 120V versions and converted them all to 230VAC.

fjk61011
May 17th, 2017, 01:01 PM
Are you sure the second 5150 has a suitable MDA/Hercules output and is not CGA?

The 5151 should work fine off the stepdown transformer as long as it's large enough to handle the load, about 100 VA.

I have two 5150 with 5151 units in 120V versions and converted them all to 230VAC.

Tried with the card that worked in the first 5150, put it in the second and monitor failed to work

fjk61011
May 17th, 2017, 01:25 PM
Are you sure the second 5150 has a suitable MDA/Hercules output and is not CGA?

The 5151 should work fine off the stepdown transformer as long as it's large enough to handle the load, about 100 VA.

I have two 5150 with 5151 units in 120V versions and converted them all to 230VAC.

Transformer is 1,000W.

How did you change the two units to 230V?

MikeS
May 17th, 2017, 04:23 PM
Are you sure the second 5150 works? Try swapping the power supplies?

paul
May 17th, 2017, 06:03 PM
Tried with the card that worked in the first 5150, put it in the second and monitor failed to work

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

Not sure if that would prevent a boot display though.

PM sent on the other item.

fjk61011
May 18th, 2017, 01:41 AM
Are you sure the second 5150 works? Try swapping the power supplies?

Yup, tried the second one with a different monitor. 5150 boots up alright.

fjk61011
May 18th, 2017, 01:43 AM
Did you change the colour/mono switch? http://minuszerodegrees.net/5150/misc/5150_motherboard_switch_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
May 18th, 2017, 09:37 PM
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
May 19th, 2017, 02:02 AM
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
May 19th, 2017, 02:37 AM
Also tried MDA card with a NEC Multisynch which works.
On the second 5150 ?

fjk61011
May 19th, 2017, 02:49 AM
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
May 19th, 2017, 03:00 AM
Do you know if your stepdown transformer connects though the ground connection ?

fjk61011
May 19th, 2017, 03:38 AM
Do you know if your stepdown transformer connects though the ground connection ?

Don't know.

modem7
May 19th, 2017, 03:54 AM
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
May 19th, 2017, 07:14 AM
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)
May 19th, 2017, 09:06 AM
Wouldn't it have been easier to use a step-down transformer?

fjk61011
May 19th, 2017, 09:31 AM
Wouldn't it have been easier to use a step-down transformer?

I have two 5150s. One with a 120 Vac input. The 5151 is also 120 Vac input powered via the pass through on the 5150. I use the step down transformer for this setup.

I hope to sell the 5150 and use the monitor with the other 5150 which is 220 Vac input. So I decided to use paul's adaption to the 5151. Does that make sense?


EDIT: I've already fried one PSU 120 Vac by forgetting and then plugging in to the mains 220 Vac.

Whilst I'm on, what colours are used for mains AC cable in America, Live/Line/Phase, Neutral, Ground/Earth?

Chuck(G)
May 19th, 2017, 09:36 AM
I guess it does. :)

fjk61011
May 19th, 2017, 09:45 AM
Getting the cover off was a challenge until I discovered the sneaky little trap doors covering the screws.

MikeS
May 19th, 2017, 09:59 AM
Whilst I'm on, what colours are used for mains AC cable in America, Live/Line/Phase, Neutral, Ground/Earth?

http://www.regiscoyne.com/tech/pwrcordcc/

Also, cords for 120V generally use a thicker gauge because the current is double for the same power (wattage).

paul
May 19th, 2017, 01:26 PM
Getting the cover off was a challenge until I discovered the sneaky little trap doors covering the screws.

Looks like you're on track with the conversion despite some variations with the parts.

If you broke the tabs off those little screw covers you could superglue on the cover underside some tiny magnets as found in CD drive laser focus actuators.

38671

fjk61011
May 20th, 2017, 02:35 AM
Looks like you're on track with the conversion despite some variations with the parts.

If you broke the tabs off those little screw covers you could superglue on the cover underside some tiny magnets as found in CD drive laser focus actuators.

38671

I don't think I broke them.

What gauge/CSA wire should I use from the PSU to the PCB?

paul
May 20th, 2017, 12:43 PM
It's just under 1 amp. Roughly about twice the diameter of the mains wires.

38690

fjk61011
May 21st, 2017, 01:32 AM
My new PSU arrived - on a Saturday. And a new soldering iron.

fjk61011
May 21st, 2017, 03:28 AM
Followed paul's instructions. Hardest part was my soldering. Checked everything, powered up my 220 Vac 5150. No blinking cursor. Oh no.

Then I remembered that I hadn't set the dip switches for MDA. Changed them to off. Switched on, blinking cursor. Boots DOS.

Treats my self to a McFlurrie. Whoop.

paul
May 21st, 2017, 12:33 PM
Well done!

fjk61011
May 21st, 2017, 01:46 PM
Well done!

After I got the cover back on I discovered two brackets left out. Can't remember were they where.

fjk61011
May 21st, 2017, 02:18 PM
Might tackle a PSU next.

paul
May 21st, 2017, 03:58 PM
Be sure to get some desoldering braid and practice a bit before tackling that.

fjk61011
May 22nd, 2017, 03:55 AM
Be sure to get some desoldering braid and practice a bit before tackling that.

I was pretty good at soldering some years ago. I did an Electronics and Computer Systems course as a mature student - the wife laughs at the mature bit. We had to built a Sound to Light circuit with three different channels. We were given the schematic and had to design our own PCB. I managed to get all the components on one side. Quite a lot of discrete components, and some op-amps if I recall rightly. Looked at it recently, soldering was pretty good. I'll do some practice before I tackle the PSU.

38724

These brackets were left over. Don't know where they went in the monitor.

paul
May 22nd, 2017, 12:30 PM
Those brackets were part of the transformer mounting, not needed now.

fjk61011
May 22nd, 2017, 12:39 PM
Those brackets were part of the transformer mounting, not needed now.

Grand so.

What wattage soldering iron should I use for the PSU adaptation?

paul
May 22nd, 2017, 05:54 PM
Well, mine is 20W but I think any electronics-oriented iron will work fine. It's technique that counts.