Philips NMS8250 Cartridgeslot: What is this for?

Por Meits

Scribe (5855)

Imagen del Meits

14-08-2018, 03:33

In this service manual on page 33 of the PDF there's a picture of the cartridge slot unit. Below the picture on the right bottom there's a code. Just above the A12 parth there's a dark black hole. On the back side it's connected to ground. On the front side the cartridge connector is blocking it.

I'd love to know because it's just next to the -12V pin with which I do have some difficulties when there when there's just a little pressure on the slot due to a bit of gravity. On most modules I have there's a little pin visible in a little bit of solder. On this particular troublesome unit there's nothing in it.

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Por Philip

Champion (373)

Imagen del Philip

14-08-2018, 10:07

I have no idea about the black hole. But to support the Modulon in the upper slot of the 8250 (because if it's in the bottom slot nothing fits in the top slot) I once made this:

Perhaps you can make something similar for this particular troublesome unit?

Por Meits

Scribe (5855)

Imagen del Meits

14-08-2018, 11:01

It's more like pushing the complete slot unit a tiny little bit. Check the -12V on the meter in this clip when I put a tiny bit of pressure on it.

ps. indeed, this 8250 is not inside a 8250 case

Por Jipe

Paragon (1381)

Imagen del Jipe

14-08-2018, 16:28

in the original slot the cartridge does not fit into the bottom
it is retained by the plastic frame

Por Wild_Penguin

Hero (596)

Imagen del Wild_Penguin

24-08-2018, 08:34

So the problem is, there's either a cold solder joint on the -12v pin (more likely), or that the -12V line gets shorted (to ground?) when pressure is applied to the slot (less likely). Check with a multimeter (the MSX powered off!) which might be the case.

If it is the latter, that is not good! I'd make sure it is not the flatcable, which might be crimped badly. If it happens with any cartridge, there's definitely something wrong with that cart slot pcb unit. I'd desolder the connector, see if there was carbage between the connector and pcb, and resolder a new one,).,