DeltaForce Echo Board

[Phuture]

Anyone know if there is a schematic for the DeltaForce Echo/AMT board? Failing this, any idea what the two chips are, i.e. IC1 and IC2? Also, need to know if D4 is anything special? Mine is shorted. I can see D2, D3 are 1N4148 marked diodes on the echo board, which are longer than the glass case of D4, so assuming it's not a 1N4148. The D4 diode I have is marked "A.10" marked vertically round the diode.

[bitbang]

I would verify the pinouts match as this is from my notes, not from a schematic. The 8 pin IC on the echo board was a LM358, the 14 pin one was M65850P and If its a newer rig, the AMT is combined and the 8 pin IC is a TBA820.

There was a 12v zener diode on some boards, other than that 4148 should be good.

Good luck

[Phuture]

Thanks very much, bitbang. I thought the diode might be a 1N4148 as there are short ones on the main board, but I wondered why on the echo board there would be two types, one longer with "1N4148" actually printed on it. Perhaps it is an ultra fast type of some sort, but I tried a 1N4148 in it yesterday anyway and I've noticed nothing functionally abnormal so far.

Cheers for the very useful info on the ICs as well! Mine has the combined echo and AMT board, probably with a faulty TBA820.

[Edd200sx]

Thanks very much, bitbang. I thought the diode might be a 1N4148 as there are short ones on the main board, but I wondered why on the echo board there would be two types, one longer with "1N4148" actually printed on it. Perhaps it is an ultra fast type of some sort, but I tried a 1N4148 in it yesterday anyway and I've noticed nothing functionally abnormal so far.

Cheers for the very useful info on the ICs as well! Mine has the combined echo and AMT board, probably with a faulty TBA820.

The tbm820 gets the blame a lot in these. I’ve found more often the actual potentiometer is faulty.

[Phuture]

Thanks Edd. Turned out to be just the diode that was faulty, but useful for future reference.