A520 how do you tell if it is NTSC or PAL

[Motormouth]

I just bought lot of random amiga items
it came with 2 a520s.  The seller says one is NTSC and one is PAL.  But he didn't remember which was which.

How can you tell them apart?  I have had an NTSC A520 for years (I live in the States), but never have really used it (I always use a high quality genlock when working with video.or even a toaster )

Further what would happen if one would connect a NTSC A520 into a PAL amiga or visa versa.

All of my Amiga are NTSC except for one PAL A500.   I might want to use the PAL A520 with the PAL A500.

[Motormouth]

I haven't tried it, but from what other people say it only affects the colour encoding on the composite out & the standard of the RF out.

If you use a PAL A520 on an NTSC Amiga then the output will be what we call PAL60. If you use the wrong one for your monitor then the display will be black and white. If your monitor can't cope with the refresh rate then it will roll, although even then some monitors can be adjusted if they have a vertical hold control.

I assume an NTSC A520 on a PAL Amiga will create NTSC50, quite how well that will be supported by TV's I don't know. Support for PAL60 is relatively common in europe, some modern games consoles output it.

Some (not sure if all) PAL A520's have a PAL standard selection switch as there are multiple audio carriers in use. There is also supposedly a different part number, but I can't find a list. If you open them up then the clock crystals are different values.

FWIW PAL and NTSC only refer to the modulator, although we refer to the A500 as PAL or NTSC it's really just 50 or 60hz (and even that can be configured using a jumper on some Amigas).

Hi,

If you can open the case to look at the circuit board, it looks like you can inspect pin 20 on the video encoder IC to determine whether the unit is PAL or NTSC.

The pictures on http://amiga.resource.cx/exp/a520 shows the encoder is an MC1377P.  According to the datasheet for the chip (http://www.datasheetcatalog.com/datasheets_pdf/M/C/1/3/MC1377P.shtml), it supports either NTSC or PAL.  To configure for NTSC, pin 20 is grounded.  For PAL, pin 20 is left disconnected.

I don't have a handy way to highlight pin 20 in the pictures, but it's one at the bottom right of the chip in the pictures showing the back side of the PCB.  Use the top side pictures to see where to find the chip, then flip to the back side to find the two rows of 10 pins.

Both of the boards shown on amiga.resource.cx appear to be PAL units, as there is break in the trace that connects to pin 20 before it reaches the ground trace.  On my NTSC unit, this break isn't present.

I'm not sure if they used the MC1477 on all units.

The 520 is kind of annoying to open.  There are four cylinders molded into the top case that have a friction fit onto pegs in the bottom (think lego block).  There aren't any clips or screws, it just takes careful prying around the edge to separate.  There's an RF shield that would need to be desoldered to inspect the top side, but since all the PCB traces are on the bottom, that's not necessary.

Robert

There are a couple of references on the internet to the A521 video modulator with prices in either pounds or Euros.

I searched for "Amiga A521"

Ernie

Thanks for all your comments!!!  I thing i really wanted to make sure that the A520 with the wrong sync (ie when 50Hz is provided and the circuits are designed for 60Hz, or visa versa) would not cause damage to the A520.  Even more importantly the wrong sync would cause a back EMF or frequency shift that would damage the Amiga.  

It is also nice to know if the wrong sync is use the colors are wrong (this makes sense if the color sync is expecting on frequency and the Luma signal is another frequency) rather than damaging things.  It is also nice to know how to change the jumpers back and forth!  Thanks!