Scandoubler recommendations

[Doppie1200]

Hi,

I uploaded three photo's. The mod I'm doing has progressed a little further than is displayed by the photo's. A passive cooler has been glued on the small ic in the lower right corner (used special thermo glue). The tinware has been adapted to fit nicely again and the harddisk bracket has been relocated.

All I need is to drill holes for the harddisk in the harddisk bracket and tinware. Then I'm done.

The photo's do not seem to appear yet. I quess the have to go by the moderators or something.


@x56h34
I think games look bad cause of the incredible dot pitch of modern crt's and the scanlines gone missing :-o
Find a poor quality vga and it all look 1084 again.
I usually take of my glasses.

[srg86]

With carefull measuring and a good modeling knife I would have thought placing it into the plasic cap could be possible (don't have a hot glue gun). Is the plastic quite thick though?

Anyway, pictures of the passive heatsync and new hard drive location would be great.

BTW are these totally nesseccary?

Anyway, if games look blurry, why not just play them on a TV (that may be what I'll do). It'll be interesting to see workbench in devastatingly sharp pictures  :-)

Anyway, just think how sharp LCDs are!!  :-o

Oh another thing, will the normal Amiga RGB port still work properly, even with a vga monitor connected to the can doubler at the same time.

srg

P.S. I'm not much of a modder.

[Doppie1200]

Hi,

I dont think the heatsink is really needed. Although the chip is getting very hot and is managing to warm up my heatsink pretty good. But alot of people are using these devices without one. I choose to release the straign on the chip. First I downloaded the datasheet which states the chip brakes down at a junction temprature of 150 degree (C). So I knew it would be safe to skip the heatsink. Hoewver I choose against it in an attempt to lenghthen its life.

When you can still toutch the chip without burning you can be sure the junction temprature is below the stated maximum. It's beyond the scope of this reply to explain junction temprature and I'm not the best person to explain it to you.


I'll post the pics of my finished mods tomorrow. The photo's are already taken but I am in no mood to get them off my camera right now

As for cutting the case. It is a matter of opinion and guts I guess. I would avoid it at any cost since it will never look as straight as something out of the factory.

As for hot glue guns. I got mine for a dime at a local DIY store. Take a look around. You need no military spec. glue gun to do this kind of project

BTW This is my first message posted with a real A1200 by me on amiga.org. That scandoubler is working great!

[Hyperspeed]

First things's first - An Amiga outputs 15Khz horizontal frequency to be compatible with a TV.

A scandoubler willdouble 15Khz to make 30Khz. PCs use 31Khz.

This means you will have to get a `Multisync' monitor or one with good range of frequency such as an NEC or Philips.

One with digital memories for different screenmodes would be very handy, maybe 10x different `channel's so you can play games that don't make use of overscan.

Another thing you need to remember is that if you have anything but an A1200 you can't use an internal scandoubler. How do you think a CD32 gets by? I reccomend everyone get an external Scandoubler WITH integrated flicker-fixer so that it can be easily swapped between Amigas.

I also reccomend you switch to NTSC as my external EZ-VGA Plus (From Eyetech) gives me faint vertical lines in 50Hz mode and it's quite flickery and dark compared to NTSC @ 60Hz. I got the impression too that 50Hz was giving me some sort of 8-bit colour limit as opposed to HAM8's 19-bit (?)...
 
My unit does get hot, particularly in the summer but it should survive most extremes of heat. Putting a fan on is optional but a good idea Doppie.

:-)

You can use an Amiga without a scandoubler/FF if you put the Multisync-Productivity driver in Devs/Monitors/ and since it doesn't use video signals like native modes you get a small, crisper mouse pointer. Albeit at the expense of ChipRAM slowdown.

One other thing to remember is that an external Scandoubler/FlickerFixer will hog the 23-pin video port so you may not be able to use a genlock. An internal one would provide it's own extra port.

[srg86]

Hyperspeed wrote:
First things's first - An Amiga outputs 15Khz horizontal frequency to be compatible with a TV.

A scandoubler willdouble 15Khz to make 30Khz. PCs use 31Khz.

This means you will have to get a `Multisync' monitor or one with good range of frequency such as an NEC or Philips.

One with digital memories for different screenmodes would be very handy, maybe 10x different `channel's so you can play games that don't make use of overscan.

Another thing you need to remember is that if you have anything but an A1200 you can't use an internal scandoubler. How do you think a CD32 gets by? I reccomend everyone get an external Scandoubler WITH integrated flicker-fixer so that it can be easily swapped between Amigas.

I also reccomend you switch to NTSC as my external EZ-VGA Plus (From Eyetech) gives me faint vertical lines in 50Hz mode and it's quite flickery and dark compared to NTSC @ 60Hz. I got the impression too that 50Hz was giving me some sort of 8-bit colour limit as opposed to HAM8's 19-bit (?)...
 
My unit does get hot, particularly in the summer but it should survive most extremes of heat. Putting a fan on is optional but a good idea Doppie.

:-)

You can use an Amiga without a scandoubler/FF if you put the Multisync-Productivity driver in Devs/Monitors/ and since it doesn't use video signals like native modes you get a small, crisper mouse pointer. Albeit at the expense of ChipRAM slowdown.

One other thing to remember is that an external Scandoubler/FlickerFixer will hog the 23-pin video port so you may not be able to use a genlock. An internal one would provide it's own extra port.

hmm

PAL = 15.6KHz * 2 = 31.2KHz
NTSC = 15.75KHz * 2 = 31.5KHz

Also my monitors will go as low as 30KHz so it's not too much of a problem.

The scanmagic/flickermagic T will work with A1200 and A4000. As the only Amigas I'd ever want to get are the A1200, A3000 and A4000 this should also not be too much of a prob (the A3000 has built in scandoubling as well as flicker fixing right?).

I also reccomend you switch to NTSC as my external EZ-VGA Plus (From Eyetech) gives me faint vertical lines in 50Hz mode and it's quite flickery and dark compared to NTSC @ 60Hz. I got the impression too that 50Hz was giving me some sort of 8-bit colour limit as opposed to HAM8's 19-bit (?)...

I think this is similar to k-disk's argument for not using external flicker fixers.

Anyway I'll keep what you said in mind  :-)

@Doppie1200
Another possibly idea is to drill a small discrete hole in the case next and in the bent part of the PCI bracket, then use a small nut and bolt, in theory to sould be harly noticable.

srg

[Hyperspeed]

Ahhh...     good point.

But you are still cutting it fine, on the borderline because you are
trying to get these VGA monitors down to 50Hz vertical refresh.

For example, I bought 2x NEC monitors of exactly the same batch and
model number. One had vertical roll syndrome and the other was fine.

Sometimes you can just miss the threshhold of luck!

:-D :-D

I wonder if an LCD would accept a scandoubled NTSC 60Hz screen at
640×480 overscan, thus keeping to the 1:1 optimum for these panels'
input resolution.

If a panel were designed for 1280x960 or 640x480 then NTSC would be
the best all-rounder for an AGA Amiga to get an LCD.

Multiscan would just slow you down and wouldn't have as high a refresh
rate as NTSC.

:-)

[Doppie1200]

Hi all,

I posted the pictures of my mod. They should appear when the moderator clears them of all offensive language  :lol:

Anyway I have a stock 17" XGA with OSD and stuff. It works really nice on 49.9 Hz. Perhaps I lucked out.

It is true that VGA is supposed to be 60 Hz.

When I get around to it I will try my 15" TFT. But since it is only 1024x768 I doubt it will get the amiga screen good on the display. The Amiga screen is 640+overscan by 512+overscan. I doubt this will be a multiple of 1024x768.

[srg86]

On paper, both my 17" and my 15" SVGA monitors will sync down to 30KHz and 50Hz, we'll see what s*d's law has to say about it.

I also have a VGA monitor from Dec 1989 although I doubt that'll work.

BTW, I never understood the term overscan.

srg

[srg86]

I can see the pictures now and their very professional looking, infact if I didn't know better, I'd think they all looked like that out of the factory.

Anyway, now I know that the scandoubler will fit under the tinware, I will probably just fit it, replace the tinware and leave the hard drive where it is, unless the heat causes any stability troubles. (Has anyone had any stability trobles because of heat of this thing?

srg

[Doppie1200]

Thanks! I'm a bit proud of it myself.
The scandoubler does fit under the tinware. The tallest chip touches the tinware though. I checked if it would short anything out but it wouldn't. However you cannot place the harddrive and the tinware on top of the scandoubler. That will not fit. Perhaps leaving off the tinware would make it fit.

As for instability. I'm having alot of instability. Freezes, crashes or sudden reboots.
Since my previous A1200 has the same trouble I'm suspecting the fastram on my accelerator.

If the trouble I'm having is related to the heat from the scandoubler I'll keep you all posted.

[srg86]

IC

The modifacations to move the hard drive - did all you do was add new holes in the tinware (as well as the caddy legs), nothin g on the motherboard?

srg

[Doppie1200]

The motherboard is untouched.

Extra slids were cut to let the shortened legs through. The legs where shortened to about one millimeter. I glued a strut under the tinware that rest on the motherboard. This provides extra strength. The tinware would bend towards the motherboard since the slids weakend it and it is not designed to carry the weight of the harddrive.

The extra holes were cut so a modern drive can be fitted.
These drives have screws on the front and back rather than in the middle. If you use an old drive you need no extra holes since the screws will be where the clock port expantion is to be. I would recommend to INSULATE the clockport header since the old screw holes are directly above the header. The head of the screw might short your address/databus sending another amiga to the recyclers.


[EDIT] The stability problems the A1200 had were not related to the mod. It was software related.

Take care!

[Daedalus]

If you (for whatever insane reason) absolutely had to use a 4/4/8 format, surely you'd choose 8 bits for green?

Yes, this is the reason for the rough gradiends and "slightly off" areas of solid colours on an AGA Amiga. Internal ones don't have this problem as they don't need to redigitise the analogue output. As to why it's 8:4:4, I've no idea... Does seem pretty odd alright...

[Hyperspeed]

@Daedalus

So only external scandoublers have this 8:4:4 colour limit? I can't
say I notice it in NTSC but I did in PAL mode. I also got noticeable
vertical lines down the screen no matter how much I adjusted the
potentiometer on the back.

My picture quality is equivalent to S-VHS I'd say, not quite RGB as on
dotted areas I notice slight signal fuzziness but the whole picture is
crisp, vibrant and full colour with my EZ-VGA Plus in NTSC 60Hz.

If you're going to use your Amiga solely on a VGA monitor there's no
reason to stick with PAL anymore anyway.

I use a 724x482 Overscan screen which gives me an extra 84x82 pixels!

:-D

Can anyone remember the name of that PD program for creating custom
screenmodes? I wonder if it works with OCS/ECS/AGA so that Doppie can
make a custom 512x384 or 1024x768 screenmode to work at his LCD's
optimum resolution.

If LCD has no visible refresh flicker then there can't be much
harm in sacrificing refresh to get a few more pixels out of your
custom chips right?

:-)

[Daedalus]

50Hz hmmm.

On my PC, I see flicker at 85Hz refresh rate on plain white. This is enough to cause me eye strain. I run my PC monitor at 100Hz.

I do have one 1989 VGA 14" VGA monitor that afaik is single sync (it has black border arround the outside of the screen so the picture doesn't fill it). at 60Hz I don't see flicker, strange.

Could this cause me problems with scandoubled Amigas on PC monitors.

Single sync doesn't have much to do with the monitor having a black border; that's just down to it being an old, "goldfish bowl" type tube  :-) Whether you see flicker or not is down to the phosphors used in the monitor. They glow for a certain length of time as the beam passes over them. The problem is that you can't change their "decay rate", so if you want a monitor capable of doing 120Hz, it's gonna look flickery at 60Hz cos if it didn't, every 2nd pass of the beam would be redundant (if that makes sense :-? ) So, a monitor from 1989 will only be made for 60Hz or so, and so will have much slower decaying phosphors than your new monitor, hence it doesn't flicker.

So, finally, it's nothing really to do with the differences between an Amiga and a PC's video output...

[Daedalus]

Hyperspeed wrote:
@Daedalus

So only external scandoublers have this 8:4:4 colour limit? I can't
say I notice it in NTSC but I did in PAL mode. I also got noticeable
vertical lines down the screen no matter how much I adjusted the
potentiometer on the back.

AFAIK, I don't have that trouble with my internal one on my 1200, but I do know the external ones use an extra A/D stage, and it's that that isn't capable of reproducing the full AGA palette. That would add significant cost to the device, and for the majority of cases isn't required.