f you have trouble with your MAX 4000 or you are going to buy one, check the serial first. We found out that whithin the production a very important change has improved chances of survival with a MAX 4000.

Here you have a view from the top into an open MAX 4000. You may look through the wholes of the cover too, using a pocket lamp or any bulb.

The power supplies are located in the rightmost front-corner.

On the left, you see into the older MAX 4000 model - on the rigth you see the later standard model

Verify the serial numbers, both are from 1996, the left is from week 34, the right from week 51 !!

The older models have 10A + 7A from the other PSU. The newer ones have 20A and the 7A from the other one. So running the old V34 modem boards or to many in an old MAX 4000 is really bad for the PSU´s

Check carefully the serial number on the bottom side of your MAX (you want to buy or get) if its smaller than 651xxxx, it may be a very old MAX.   You should avoid, to buy it. If you need one for production, dont even think about it (the old one). You get almost new ones for small money, T1 model in the US, E1 units from us.

the old one, avoid it !