Author Topic: Got amstrad pcw 8256 but the fun don't lasted very long ...... :O  (Read 14126 times)

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Offline 1024MAK

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Use one filter between the PSU and the monitor circuitry, another between the PSU and the disk drive, for each supply line.


Mark
Looking forward to summer in Somerset :-)

Offline JonB

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Now that's interesting, Mark, I have one of those inductors that I pulled off the power circuit. It has 2 coils, 4 legs and is marked 1022C. It used to carry the mains voltage (live and neutral) to the power board. Might work?

Offline Sebastian Blanco

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Hey jonb can you post the link to the psu you purchased for the PCW ?, i need to buy one.
The ones i got are quite nasty and very noisy.


Offline JonB

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Offline JonB

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I fitted the new power supply and it is working, but I still see motor interference.

I tried the circuit that Mark suggested, but it didn't help. Maybe because the inductor I used was the big one from the mains input line (I think it is L1 on the schematic).


@1024MAK how important are the inductor / capacitor values?

No interference with uIDE accesses though!
« Last Edit: 17:12, 17 February 17 by JonB »

Offline 1024MAK

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Well, ideally you choose the values of the capacitors and the inductor to act as a blocking filter at the fundamental frequency of the interference. But that means finding out the frequency and doing the calculations. Search the Internet for "π-filter" (PI filter) and for "T-filter" for more info...

The mains choke that you have is not likely to be suitable. You need an inductor (a DC type that will not saturate with the normal DC current flowing) that can pass a high DC current (2A or more) with a high inductance. Go for a fairly high inductance value. Here are some examples from Farrell UK. Higher values of inductance are more effective for lower frequencies of interference.

You can also add low ESR 470uF electrolytic capacitors in parallel with C1 and C2 in my ASCII schematic shown above.

The filter cannot help if the interference is getting through via the 0V line.

Mark
« Last Edit: 21:42, 17 February 17 by 1024MAK »
Looking forward to summer in Somerset :-)

Offline Bryce

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I fitted the new power supply and it is working, but I still see motor interference.

I tried the circuit that Mark suggested, but it didn't help. Maybe because the inductor I used was the big one from the mains input line (I think it is L1 on the schematic).


@1024MAK how important are the inductor / capacitor values?

No interference with uIDE accesses though!


A capacitor and a diode and you should be fine.

Bryce.

Offline 1024MAK

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The problem is, without knowing what is happening electrically, any proposed solutions are guess work.
An "isolation" diode followed by a electrolytic "storage" capacitor may help if the problem is the PSU output voltage dropping (dipping) with a sudden high current load.

If this is the case, then a "star" wiring system may help as well. By this I mean, run separate wires from the PSU output terminals to the computer, another set for the monitor circuitry, and a third set for the disk drive power feed.

You may have to use all three ideas (filters, diodes, star wiring). If you do, the filter should be after the diode.

Mark


Looking forward to summer in Somerset :-)

Offline JonB

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The problem is, without knowing what is happening electrically, any proposed solutions are guess work.


Understood, and sorry, I wasn't complaining, just reporting back.


I will have to explore these other options as I really don't want to be buying yet another power supply. I have all the parts scavenged from the PCW's power board, although I'm soon to be a bit busy sorting out these uIDE orders (quite a few of which need me to assemble....  ???


Offline 1024MAK

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Understood, and sorry, I wasn't complaining, just reporting back.
Never said anything about complaining  :-\

Don't do a Beyoncé and put a ring on it, but do put a digital storage 'scope on it!  ;D

Mark
Looking forward to summer in Somerset :-)

Offline Audronic

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@1024MAK


What would be a suitable Digital Storage 'scope ?


Thanks     Ray
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If it Ain't Broke PLEASE Don't Fix it.
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Offline 1024MAK

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What would be a suitable Digital Storage 'scope ?
One that can capture a "waveform" using the "single trace" / "one shot" trigger (where you arm it, then when the 'scope senses the change in level for triggering, it records one "waveform" into it's memory). You can then view it on screen after the event.

Or are you asking which 'scope should you buy?

Mark
Looking forward to summer in Somerset :-)

Offline Audronic

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Or are you asking which 'scope should you buy?

Mark

Hi Mark

Yes " Or are you asking which 'scope should you buy?"

Thanks    Ray
Procrastinators Unite,
If it Ain't Broke PLEASE Don't Fix it.
I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.

Offline JonB

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I can answer that: Rigol DS1054Z 4 channel scope with hackable firmware that upgrades it to a much higher specification that you normally have to pay four times the amount for.

Disclaimer: It's the only one I have direct experience with, but it seems like most people swear by them. Check out the eevblog forum, the "best scope" question comes up often.
« Last Edit: 11:40, 18 February 17 by JonB »

Offline Bryce

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Or the MSO Version. It's more difficult to hack, but it has a 16 channel Logic Analyser built in.

Bryce.

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Offline Audronic

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Thanks JonB - Bryce


I will have a look for them.


Ray
Procrastinators Unite,
If it Ain't Broke PLEASE Don't Fix it.
I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.

Offline 1024MAK

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I have a Rigol DS1052D Mixed Signal Oscilloscope and a PicoScope 3206MSO 200 MHz 2 Channel Pico PC Oscillosope

The PicoScope 3206MSO model that I have is no longer made, but later models are available.

I also have a 20MHz dual channel analogue 'scope and an earlier PicoScope model.

Mark
Looking forward to summer in Somerset :-)

Offline Bryce

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I won't list all the scopes I have, but one of them is a Rigol MSO1104S-Z. It's hackable but the hack requires opening the scope and dumping the contents of the FPGA via JTAG, which most users probably won't be happy doing. I'Ve hacked mine, but even without being hacked, it has everything that you would need for retro repair and development.

Bryce.

Offline Sebastian Blanco

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I can confirm that using separated +12 and +5 psus fix the problem no interference at all.

Offline JonB

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Which ones did you buy?

Offline Sebastian Blanco

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Just a pair of random switched psus pick them in a flea market, the 12v one is 3 amps and seem to be from a hard drive and the +5 also 3 amps switched.

Offline Sebastian Blanco

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I have only to clean it now :P
« Last Edit: 05:26, 26 February 17 by Sebastian Blanco »

Offline Sebastian Blanco

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Offline JonB

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I have ordered one - we'll see if it works!

Offline Bryce

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How many amps does the system pull from the 12V rail? That filter will already be struggling at a little over 1A.

Bryce.

Gesendet von meinem Motorola DynaTAC 8000X mit Tapatalk.