Acorn AKF-12 monitor - UK Vintage Radio Repair and Restoration Discussion Forum

Waler97 · 1st May 2015, 8:43 pm

Hi all.

A couple of years ago I picked up a full acorn A3000 setup, including an AKF-12 colour monitor. Unfortunately the monitor has recently failed. When switched on, the power light does not come on and no picture is produced at all. All that happens now is a high pitched squeal (different to the squeal it would normally produce in operation) is produced. When the monitor is switched off this noise gradually decreases in pitch before going silent. Does anybody know what the problem might be and how I might go about fixing it?

Many thanks

Liam

M6BWJ

Nicklyons2 · 1st May 2015, 11:23 pm

It could be all manner of things but I'd put Line Output and/or power supply problems high on the list. Given CRT computer monitors are now virtually worthless would it not be easier to just get another monitor? or do you want the actual 'badged' monitor? If you can't find an actual badged one but could live with one of the correct appearance & vintage have a look for Philips CM8833 it was a popular and reliable monitor of that era and there's one on E-bay at the moment - if you fancy it just make sure it has the correct type of inputs you require.

Waler97 · 2nd May 2015, 12:11 pm

I think I may just do that. I've never attempted servicing a modern(ish) CRT display and I really don't think it's worth my time. Unfortunate but these things happen I suppose.
On the bright side, it's an ideal unit for spares now.

Many thanks

nigelr2000 · 6th May 2015, 2:46 pm

Pop the back off and look for dry joints especially round the the line and SMPS transformers as the steadily decreasing whistle sounds like there's no load on the PSU.

Worth a try before you bin it.

cmjones01 · 6th May 2015, 3:03 pm

The AKF12 *is*, I believe, a rebadged Philips CM8833. As such, it's becoming more and more desirable - high-quality CRT computer monitors capable of scanning at 15kHz are gradually dying out. It's worth saving if you can. There should be lots of information on line about the CM8833 because it was used with loads of computers of the era - the BBC Micro, Archimedes and Amiga for a start.

Chris

KeithsTV · 6th May 2015, 8:34 pm

The service manual for the CM8833 is readily available, just google CM8833 service manual.

As mentioned the symptoms indicate a power supply or more probably Line output fault.

Keith

1st May 2015, 8:43 pm	#1
Waler97 Retired Dormant Member Join Date: Apr 2015 Location: Leicestershire, UK. Posts: 14	Acorn AKF-12 monitor Hi all. A couple of years ago I picked up a full acorn A3000 setup, including an AKF-12 colour monitor. Unfortunately the monitor has recently failed. When switched on, the power light does not come on and no picture is produced at all. All that happens now is a high pitched squeal (different to the squeal it would normally produce in operation) is produced. When the monitor is switched off this noise gradually decreases in pitch before going silent. Does anybody know what the problem might be and how I might go about fixing it? Many thanks Liam M6BWJ

1st May 2015, 11:23 pm	#2
Nicklyons2 Octode Join Date: Jan 2013 Location: Barnsley, South Yorkshire, UK. Posts: 1,517	Re: Acorn AKF-12 monitor It could be all manner of things but I'd put Line Output and/or power supply problems high on the list. Given CRT computer monitors are now virtually worthless would it not be easier to just get another monitor? or do you want the actual 'badged' monitor? If you can't find an actual badged one but could live with one of the correct appearance & vintage have a look for Philips CM8833 it was a popular and reliable monitor of that era and there's one on E-bay at the moment - if you fancy it just make sure it has the correct type of inputs you require.

2nd May 2015, 12:11 pm	#3
Waler97 Retired Dormant Member Join Date: Apr 2015 Location: Leicestershire, UK. Posts: 14	Re: Acorn AKF-12 monitor I think I may just do that. I've never attempted servicing a modern(ish) CRT display and I really don't think it's worth my time. Unfortunate but these things happen I suppose. On the bright side, it's an ideal unit for spares now. Many thanks

6th May 2015, 2:46 pm	#4
nigelr2000 Heptode Join Date: Nov 2008 Location: North Walsham, Norfolk, UK. Posts: 900	Re: Acorn AKF-12 monitor Pop the back off and look for dry joints especially round the the line and SMPS transformers as the steadily decreasing whistle sounds like there's no load on the PSU. Worth a try before you bin it.

6th May 2015, 3:03 pm	#5
cmjones01 Nonode Join Date: Oct 2008 Location: Warsaw, Poland and Cambridge, UK Posts: 2,677	Re: Acorn AKF-12 monitor The AKF12 is, I believe, a rebadged Philips CM8833. As such, it's becoming more and more desirable - high-quality CRT computer monitors capable of scanning at 15kHz are gradually dying out. It's worth saving if you can. There should be lots of information on line about the CM8833 because it was used with loads of computers of the era - the BBC Micro, Archimedes and Amiga for a start. Chris __________________ What's going on in the workshop? http://martin-jones.com/

6th May 2015, 8:34 pm	#6
KeithsTV Nonode Join Date: Aug 2007 Location: South Bradford, West Yorkshire, UK. Posts: 2,573	Re: Acorn AKF-12 monitor The service manual for the CM8833 is readily available, just google CM8833 service manual. As mentioned the symptoms indicate a power supply or more probably Line output fault. Keith