[Solved] CR103 Triac Replacement/DDT Problem

[jao6622]

Hi folks, a long time ago I bought a used Peavey CS800 with a fault which doesn't let me use the DDT on channel B, i noticed that component CR103 is missing on channel B.
With DDT in defeated position , the amplifier works fine

In channel A the CR103 is a TRIAC BT08-400S, I have seen that originally came with a SAC187 TRIAC and is replaced with the BTA16-800B (in CS800X) or some similar component

The question is... that missing BTA-08-400S could be replaced by a BTA-08-600B?

Sorry for my bad english , i have used Google Translate

Channel B


Channel A

[Enzo]

No, that would not affect the DDT.

If the channel works OK with DDT off, explore the DDT circuit itself on that channel.

[jao6622]

No, that would not affect the DDT.

If the channel works OK with DDT off, explore the DDT circuit itself on that channel.

Oh well , where is located the ddt circuit? and , would recommend me installing that missing triac? Or leave it as it is?

PD: is a wind tunnel CS800 model

[Enzo]

The triac only activates when the amp goes to DC on the output or otherwise causes trouble. Then the triac turns on and shorts the output. it does this to prevent your speakers catching on fire. Seriously.

The DDT is the stuff involving U104, 103, 106 and associated parts.

[jao6622]

The triac only activates when the amp goes to DC on the output or otherwise causes trouble. Then the triac turns on and shorts the output. it does this to prevent your speakers catching on fire. Seriously.

The DDT is the stuff involving U104, 103, 106 and associated parts.

Thanks for help Enzo , but I saw the components of the DDT and I did not see something visibly abnormal, the question would be to test those ICs (which I have no idea how to test them) and well, I want to add that triac for that of the protection of the speakers. Would that BTA08-600B be a replacement for the BTA08-400S?

U104,105,106 zone




Here's a video of the DDT enable fault

https://www.youtube.com/watch?v=F-rhZbpuLi0

Without DDT Enabled (everything OK)

https://www.youtube.com/watch?v=uZbg9AfbOOQ

[Enzo]

99% of electronic failures don't look any different, any more than the water pump in your car looks different if it goes bad.

I don't know the BTA parts, in general, you need to meet the original voltage and current specs or exceed them. so 600v is fine in place of 400v and 12A is fine replacing 10A etc,.

If you think the DDT is messing with you, I test the parts by removing the 87478 IC, does the full sound restore?

[jao6622]

99% of electronic failures don't look any different, any more than the water pump in your car looks different if it goes bad.

I don't know the BTA parts, in general, you need to meet the original voltage and current specs or exceed them. so 600v is fine in place of 400v and 12A is fine replacing 10A etc,.

If you think the DDT is messing with you, I test the parts by removing the 87478 IC, does the full sound restore?

I have removed the 87478 from channel B and tested with DDT enabled , The channel B continued working without any problems , i have tested that IC in the Channel A and it stopped working (same fault of B) , the 87478 on channel B is faulty , I have to replace it . Thanks for help Enzo!