Acorn 28-AKF17 Monitor

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sixxdog_uk
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Acorn 28-AKF17 Monitor

Post by sixxdog_uk » Sun Apr 10, 2016 8:53 am

Hi Guys ,

Does anyone happen to have a broken Acorn 28-AKF17 Monitor?

I have one where the push power switch is broken and I'm looking for a donor.

Thanks for looking.

Alex :-)

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Re: Acorn 28-AKF17 Monitor

Post by jonb » Sun Apr 10, 2016 9:05 am

Hi Alex

I don't have one, but it's possible you could source a power switch that fits from eBay.Just remove the existing one and look for a close match; it's not that hard to find something. I did this on one of my CP/M machines and, while not exactly 100% perfect, it does look OK and works well.

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Re: Acorn 28-AKF17 Monitor

Post by jonb » Sun Apr 10, 2016 9:11 am

PS, did your Electron work in the end?

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Re: Acorn 28-AKF17 Monitor

Post by bleeper » Sun Apr 10, 2016 10:03 am

Were these monitors just badly designed or something? I've had two of the same model with faulty power buttons.

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Re: Acorn 28-AKF17 Monitor

Post by flaxcottage » Sun Apr 10, 2016 10:06 am

I have an AKF30 with exactly the same problem. A small piece of wood cut to size holds the switch ON so the monitor is usable. I now just switch the mains socket for the monitor.

It works for me. :)
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Re: Acorn 28-AKF17 Monitor

Post by 1024MAK » Sun Apr 10, 2016 10:18 am

I think you will find, the latching mechanism is all that has failed. It is a common fault with this type of switch. A lot of TVs and monitors fitted with this style of switch all suffer from this fault. We had a Panasonic TV where the switch failed in exactly the same way.

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Re: Acorn 28-AKF17 Monitor

Post by Ottly » Mon Apr 11, 2016 12:03 am

Take a look at my thread and see if the power switch is similar or the same? A lot of these monitors are the same on the inside.

viewtopic.php?f=45&t=10948

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Re: Acorn 28-AKF17 Monitor

Post by RobC » Mon Apr 11, 2016 8:28 am

I think this is the part you need:

http://www.donberg.co.uk/descript/s/sw_28.htm

I've got several Acorn/Philips CM8833 type monitors and they've all failed in this way at some point.

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Re: Acorn 28-AKF17 Monitor

Post by sbadger » Mon Apr 11, 2016 2:56 pm

agree with robc, on the cm8833 the power switch is a known weak point, if you can't find. can't be bothered, many people just screw a clip in to hold the power button down, the monitor works fine then.

Like post #7 here

http://eab.abime.net/showthread.php?t=51021
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Re: Acorn 28-AKF17 Monitor

Post by johnkenyon » Tue Apr 12, 2016 3:31 pm

1024MAK wrote:I think you will find, the latching mechanism is all that has failed. It is a common fault with this type of switch. A lot of TVs and monitors fitted with this style of switch all suffer from this fault. We had a Panasonic TV where the switch failed in exactly the same way.

Mark
If you have a look at http://img.weiku.com/waterpicture/2011/ ... 9824_1.jpg you will see a small bit of stiff metal wirewhich has one end in a hole in what looks like PCB like material on the top, and the other end stuck in a smaller hole+wedged under the spring.

Take that bit of metal out of a push switch (or damage the plastic channel underneath that larger hole on the button shaft), and your once latching switch turns into a non-latching one...

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Re: Acorn 28-AKF17 Monitor

Post by zeem » Thu Apr 14, 2016 8:01 pm

My technique for devices with broken power switches has been to solder the wiring together, on one of the pins of the duff switch, to make it always-on. This looks neater from the outside than wedging the button down.

The last thing I did this on was a Philips Computer Monitor 80 (green screen), that I later sold, and wish I'd kept...

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Re: Acorn 28-AKF17 Monitor

Post by CanonMan » Fri Apr 15, 2016 5:05 pm

Please post a photo or two of the switch you need a replacement for.

I still have a few NOS switches in my stash and may well have the one you need.

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Re: Acorn 28-AKF17 Monitor

Post by 1024MAK » Fri Apr 15, 2016 5:14 pm

On the subject of monitor switches, saw this while browsing evil bay... Power-switch-for-Philips-CM8833-Commodore-1084-Monitors

Mark

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Re: Acorn 28-AKF17 Monitor

Post by eisdielenbiker » Wed Sep 11, 2019 8:50 am

Does any one happen to have information on the rgb socket layout of the AKF17 ?
Does this 9-pin-male socket differ from the common Commodore/Philips monitors then ?
Or did just the Acorn 9-pin-RGB cable sort out those connections the right way as the Acorn being known for off-standards pin outs ?

I would like to connect my AKF17 to both an AtariSTE in colour mode and A3010 and in the the future to some A420.
Last edited by eisdielenbiker on Wed Sep 11, 2019 8:52 am, edited 1 time in total.
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Re: Acorn 28-AKF17 Monitor

Post by johnkenyon » Wed Sep 11, 2019 9:14 am

eisdielenbiker wrote:
Wed Sep 11, 2019 8:50 am
Does any one happen to have information on the rgb socket layout of the AKF17 ?
Does this 9-pin-male socket differ from the common Commodore/Philips monitors then ?
Or did just the Acorn 9-pin-RGB cable sort out those connections the right way as the Acorn being known for off-standards pin outs ?

I would like to connect my AKF17 to both an AtariSTE in colour mode and A3010 and in the the future to some A420.
Page 4 of https://www.retro-kit.co.uk/user/custom ... te-249.pdf has the AKF17 pinout (RGB at TV type scan rates)

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Re: Acorn 28-AKF17 Monitor

Post by Kazzie » Wed Sep 11, 2019 9:16 am

eisdielenbiker wrote:
Wed Sep 11, 2019 8:50 am
Does any one happen to have information on the rgb socket layout of the AKF17 ?
Does this 9-pin-male socket differ from the common Commodore/Philips monitors then ?
Or did just the Acorn 9-pin-RGB cable sort out those connections the right way as the Acorn being known for off-standards pin outs ?

I would like to connect my AKF17 to both an AtariSTE in colour mode and A3010 and in the the future to some A420.
This other thread suggests that it is a rebadged Phillips CM8833-mkII. Elsewhere I've found the following pinout for it:

Code: Select all

Philips CM8833-II has a RGB connector which can accept both analogue and digital
RGB signal. The RGB connector uses the following pinout: 

_____________
\ 5 4 3 2 1 /
 \_9_8_7_6_/

 -Pin-    -RGB TTL-     -RGB Analogue-
   1      Ground        Ground
   2      Ground        Ground
   3      Red           Red
   4      Green         Green
   5      Blue          Blue
   6      Intensity     Fast Blanking
   7      Not used      Composite Sync
   8      H. Sync       H. Sync
   9      V. Sync       V. Sync     

Some of the CM8833-II models have also a sepearate composite video input
(RCA connector).
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Re: Acorn 28-AKF17 Monitor

Post by eisdielenbiker » Wed Sep 11, 2019 11:13 am

Thanks, what about that original 9-pin cable that came with this Acorn screen ?
Is there a proof that it is the correct one? I know you can kill screens with wrong horizontal frequency...
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Re: Acorn 28-AKF17 Monitor

Post by Kazzie » Wed Sep 11, 2019 11:52 am

eisdielenbiker wrote:
Wed Sep 11, 2019 11:13 am
Thanks, what about that original 9-pin cable that came with this Acorn screen ?
Is there a proof that it is the correct one? I know you can kill screens with wrong horizontal frequency...
Acorn Application Note 249 Connection of Monitors to Acorn Computers gives an official source for the pinout of the AFK17 (on the monitor, rather than the cable) on page 4.

The pinout for the 9-pin video output on the A420/1 is shown on page 8 of the A400/1 Service Manual, and for the A3000 on page 22 of its Technical Reference Manual. The only difference between them is that the A3000 describes support for separate vertical and horizontal sync as well as composite, whereas the A400/1 only describes composite sync.

At the Archimedes end, the pinout is:
  1. Red
  2. Green
  3. Blue
  4. Horiz / Comp Sync
  5. Vert Sync / Mode (A3000 only)
  6. 0V
  7. 0V
  8. 0V
  9. 0V
Links LK24-27 on the A3000 configure the behaviour of pins 4 and 5 on the video socket. The AFK17 only supports a composite sync, so take a look inside your machine to check that LK24 is in position 2-3, as described on page 20 of the Technical Manual. (Conveniently, using composite sync means that your cable will work with both the A3000 and A420.)

After this, you can use the continuity test function of a multimeter to check how the pins at one end of the cable are connected to the pins at the other end. You should find that:
  • Pin 1 at the machine end (Red) is connected to pin 3 at the monitor end
  • Pin 2 at the machine end (Green) is connected to pin 4 at the monitor end
  • Pin 3 at the machine end (Blue) is connected to pin 5 at the monitor end
  • Pin 4 at the machine end (C Sync) is connected to pin 7 at the monitor end
  • Pin 5 at the machine end (V Sync) is left unconnected
  • Pins 6, 7, 8 and 9 (0V) are all connected together, and to pin 1 at the monitor end
(At the monitor end, pins 2, 6, 8 and 9 will be unconnected)
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Re: Acorn 28-AKF17 Monitor

Post by eisdielenbiker » Thu Sep 12, 2019 7:10 am

Thank you very much for this elaborate description!

Last night while watching tv I measured a few 9-pin and 15-pin video cables and adapters.

I found 1 Adapter which is labeled "PS2 VGA <-> HD15" that will fit straight on to the A420 via standard 15-pin VGA cable and will allow
my BenQ912 to display Archimedes video. (Precondition is a repaired A420 though)

Second I found a short 9-pin cable that will go straight from A420 to CM8833II/Acorn CRT AKF17.

Last bot not least I have to look for a connection from 15-pin vga video of my running A3010 to the Acorn AKF17 CRT.
I guess a VGA cable plus PS2-VGA-HD15 adapter plus gender changer 9-9-pin I have found won't do.
At the moment I am using this BenQ LCD screen. It is offending the eye a little although being versatile no doubt.

How do you connect A30x0 to SUB-D-9-pin CRTs in general ?
Last edited by eisdielenbiker on Thu Sep 12, 2019 7:21 am, edited 4 times in total.
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Re: Acorn 28-AKF17 Monitor

Post by Kazzie » Thu Sep 12, 2019 8:14 am

eisdielenbiker wrote:
Thu Sep 12, 2019 7:10 am
Thank you very much for this elaborate description!

[...]

How do you connect A30x0 to SUB-D-9-pin CRTs in general ?
You're very welcome. Though I made the mistake that you had an A3000, not an A3010. :oops:

In the A3010 Welcome Guide there is guidance on how to connect it to various different types of monitors, including the AFK17. It describes the exact pinout of the cables you'll require, You'll find it on page 67 (page 79 in the PDF numbering).
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Re: Acorn 28-AKF17 Monitor

Post by eisdielenbiker » Fri Sep 13, 2019 6:24 am

I will solder a designated adapter cable from a VGA cable to connect my 3010 to the AKF17. No problem.
There is valuable information inside this Welcome Guide. I did not bother until now. This ID-setting for some monitor sensing is interesting.
Will be trying to adapt it to my new cable.
So Acorn were selling small adapters typed B through F ? Never seen any of these. Have you ?
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Re: Acorn 28-AKF17 Monitor

Post by Kazzie » Fri Sep 13, 2019 9:21 am

eisdielenbiker wrote:
Fri Sep 13, 2019 6:24 am
I will solder a designated adapter cable from a VGA cable to connect my 3010 to the AKF17. No problem.
There is valuable information inside this Welcome Guide. I did not bother until now. This ID-setting for some monitor sensing is interesting.
Will be trying to adapt it to my new cable.
So Acorn were selling small adapters typed B through F ? Never seen any of these. Have you ?
I'm not sure they were selling adapters, rather that they'd sell a suitable cable with an Acorn-branded monitor. The A420/1 and CM8833-MkI that I salvaged from my high school was equipped with a variant of cable type E (but for the 9-pin DE connector of the A420/1), which I presume is original equipment.

The information in that appendix was aimed at people who bought an Archimedes but didn't buy a new monitor at the same time (who could show the page to a computer shop or dealer to get a cable bought or made), or for dealers who sold custom packages according to their customers' requirements. The fact that it's so useful to us decades later is a happy side effect!
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Re: Acorn 28-AKF17 Monitor

Post by eisdielenbiker » Tue Sep 17, 2019 10:49 am

I see. One question remains as I want to use this CRT for several old computers from Archimedes to Atari STE:
Where ist Pin #1 located if you you look upon this male connector at the AKF17 ?
Some Atari cable I have here is confusing my efforts to connect the CRT properly at all.
After confirming one correctly routed A420 cable I am in big doubt if sth. is mixed all around in a mirror way.
Just Acorns Application Note #249 at page 4 is confusing me since this morning:

Pin #1 is top left !? Was assuming top right til now.

"NB. The AKF17 pinout above is the pinout of the connector actually on the rear of the monitor, and NOT of
the end of the patch lead which connects it to the computer."

I had no opportunity to check any Acorn because my 420 is disfunct and for the 3010 the gender changer is still missin.
My Mega STE only gave some of the 3 base colour lacking instable picture (lacking some sync too)
Last edited by eisdielenbiker on Tue Sep 17, 2019 10:55 am, edited 3 times in total.
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Re: Acorn 28-AKF17 Monitor

Post by Kazzie » Tue Sep 17, 2019 12:53 pm

eisdielenbiker wrote:
Tue Sep 17, 2019 10:49 am
I see. One question remains as I want to use this CRT for several old computers from Archimedes to Atari STE:
Where ist Pin #1 located if you you look upon this male connector at the AKF17 ?
Some Atari cable I have here is confusing my efforts to connect the CRT properly at all.
After confirming one correctly routed A420 cable I am in big doubt if sth. is mixed all around in a mirror way.
Just Acorns Application Note #249 at page 4 is confusing me since this morning:

Pin #1 is top left !? Was assuming top right til now.

"NB. The AKF17 pinout above is the pinout of the connector actually on the rear of the monitor, and NOT of
the end of the patch lead which connects it to the computer."
That's my interpretation of Application Note 249 too. No.1 top left when looking at the rear of the monitor.

(Top right it you're looking at the end of the cable that connects to the monitor).
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Re: Acorn 28-AKF17 Monitor

Post by eisdielenbiker » Tue Sep 17, 2019 12:57 pm

I will just open the CRts backcase and have a look inside before solderinge any new adapter/cable.
It needs some restoration anyhow....Although it only looks bad from the outside. Internally it seemed very
clean whe I had a quick look inside some time ago. Hopefully it is not that fine monitor which is faulty...
Last edited by eisdielenbiker on Tue Sep 17, 2019 12:58 pm, edited 2 times in total.
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Re: Acorn 28-AKF17 Monitor

Post by IanS » Tue Sep 17, 2019 8:10 pm

eisdielenbiker wrote:
Tue Sep 17, 2019 10:49 am
Pin #1 is top left !? Was assuming top right til now.
Read the pin numbers from the connectors. I've yet to see a D-type connector that doesn't have the pin numbers in the plastic moulding.

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Re: Acorn 28-AKF17 Monitor

Post by eisdielenbiker » Wed Sep 18, 2019 1:29 pm

You are right pin numbers are embossed there right at the backplate of the monitor. Top left is #1.

And now I am pretty sure that the monitor is faulty:
1) it is lacking green
2) it is lacking Vsync

I had opened cleaned and resoldered a few monitors of different retro computers. But this behaviour in its combination was all new.
And there are so little knobs to adjust internally :-(

Lacking colour ist most probably due to a faulty blue driver transistor at the CRT neck pcb, I believe. The board is well seated to the neck.
If I find a schematic I could possibly fix that Vsync problem by much more easy means too. But visually I did not just get to the point.

In the end you are compensating ageing components by adjusting some trimmer.

Regards Mark

BTW. I have ordered the minimum batch of 3 power switches available at amibay.com for this monitor and different 1084 with a rear side switch location.
Last edited by eisdielenbiker on Wed Sep 18, 2019 1:31 pm, edited 2 times in total.
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Re: Acorn 28-AKF17 Monitor

Post by Kazzie » Wed Sep 18, 2019 2:25 pm

Note that the AKF-17 doesn't support a Vsync - it expects a composite sync input on pin7!

Given that the AKF-17 is a re-badged Phillips CM8833-MkII, the service manual for the CM8833 (MkI) may be a good starting point.

Have you tried the CVBS (composite video) input, to see if that works? Any differences could help diagnose where the fault is.
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