Signat RAM 2 Mark II in protect

[Mote]

I have looked at these Signat amps and finally got the courage to buy a broken one. But now I do not know what to do with it.
I have narrowed the search down to one of four channels, when I remove outputs from it amp powers up and does not go into protect.
Outputs dont seem to be the fault, they test out fine out of the board, after installing new ones, amp still goes into protect.
Protection on this amp works like in periods, it tries to power itself up in every 10 seconds. Measuring DC current on speaker terminals of the problematic channel shows that during this attempt to power up rail voltage appears on them and all three legs of all 4 outputs in that channel.
With outputs out of the circuit there is rail voltage on center solder pad for output transistors, no voltage on 1st and 3rd pad.
That would indicate that outputs were shorted but none of the 8 transistors I tried are shorted.
This amp uses custom driver chips/boards, could it be toast?

[Perry Babin]

I have no experience with these but it's possible that the driver module is defective. You could swap the one from the defective channel to one of the good channel to see if the fault follows the module. Before you do that, you should confirm that the module drives the outputs directly. If it drives the outputs through driver transistors, check the driver transistors before swapping the modules.

[Mote]

I recently tried to fix an amp with similar driver modules but they are so brittle and soldered from two sides. I ended up breaking it.
There are only a few transistors per channel besides outputs, I did not find any shorted transistors.
But I guess I have to try and swap the modules because there is not much else I can do.

[Perry Babin]

If you can get ChipQuik in your area, it will make removing this type of module VERY easy. You'll never damage a module again.

[Mote]

Yes I have seen ChipQuik video on youtube, found a supplier in Estonia as well.
This time I managed without it and yes, moving the module to another channel made the symptoms go to another channel. So the module is defective.
There is no chance of getting a new one, Signat doesnt even have a proper home page I doubt they give me any info on how to repair this amp.

Advice to all, if you see a broken amp like this: dont buy it.

[gisewhcs]

Have a look for older, grey EmPhaser, Altai, Limit Amps etc.pp.
They use the same driver boards.
That was a ChungLam Thing at that time.

[Tom7227]

I would be interested in buy your good one. Does it say CHS-200 on it?

[Mote]

No, mine say CH-400 on it.
CHS-200 I think you can find in RAM 1, thats 6 channel version.
There is a RAM 1 for sale in Estonia, I thought about buying it, so I could get one working amplifier (RAM 1 contains both CH-400 and CH-200), but the guy asks 60 euros for it.

[Tom7227]

I would love to find the availablity of that module. I am repairing an amplifier for someone.

Do you have contact information ?

Tom7227@aol.com