Dx Blame MKIII-Hx - Builder's thread

[AndrewT]

No.
4700uF +4700uF connected in series = 2350uF

60Vdc is very close to the 63V maximum rating for the majority of affordable smoothing caps.

You may find that in worst case conditions that your mains supply takes your smoothing caps above 63Vdc. That will require you to specify 75V or 80V capacitors.

[BMW850]

Can someone tell me how a speaker protection module works?
Works a speaker protection module only if the module gets voltage from the amplifier?
I hear no click after 10 seconds as it is connected, see picture 2
The small transformer is 1 x 12 volt.

Regards,
Rudy

[BMW850]

Another photo, this is the good way how the amplifier is connected to the module?

Regards,
Rudy

[currentflow]

Originally Posted by BMW850

Can someone tell me how a speaker protection module works?
Works a speaker protection module only if the module gets voltage from the amplifier?
I hear no click after 10 seconds as it is connected, see picture 2
The small transformer is 1 x 12 volt.

Regards,
Rudy

Hi,

According to the circuit diagram found here, that module connects between the amplifier output and the loudspeaker. When powered by a 12Vac supply, if a DC offset of positive or negative polarity is detected at the amplifier output, the relay contacts open and disconnect the load. There is also a delay of a few seconds before the relays close at power-up.

Regards,
currentflow

[BMW850]

Works a speaker protection module only if the module gets voltage from the amplifier?
I hear no click after 10 seconds as it is connected.

Regards,
Rudy

[currentflow]

Originally Posted by BMW850

Another photo, this is the good way how the amplifier is connected to the module?

Regards,
Rudy

From your post #983, the 12V transformer is incorrectly wired. If you don't have a centre-tapped transformer, the transformer leads should go between "0" and one of the "AC" terminals. In this way, you will only achieve half-wave rectification of the 12V supply and this may be insufficient to power the circuit.

There has to be no voltage from the amplifier for the relays to connect the output to the speakers.

[BMW850]

Kevin emailed me this:
Dear Sir:
http://www.okaphone.nl/product/images/212048c.jpg
This transformer is 12-0-12 full wave output.
What you need should be simpler one. Just need to have one 12-0 output, 1A current is quite enough.

Sincerely, Kevin
- vintage_audio_lab

Oke currentflow, I wire one to the 0 and the other to the AC.

Thanks

[currentflow]

Originally Posted by BMW850

Kevin emailed me this:
Dear Sir:
http://www.okaphone.nl/product/images/212048c.jpg
This transformer is 12-0-12 full wave output.
What you need should be simpler one. Just need to have one 12-0 output, 1A current is quite enough.

Sincerely, Kevin
- vintage_audio_lab

Oke currentflow, I wire one to the 0 and the other to the AC.

Thanks

If you are using an external single-ended transformer in this circuit and not a 12V-0-12V type, you should verify that the on-board 12V regulator has sufficient input voltage to regulate correctly. Unless a low-dropout 12V regulator has been fitted, you will require at least 14.5V DC at the input to the regulator under load (i.e. relays activated) and measured between the junction of D1-D2 and GND. I don't envisage this will be a problem as you should be able to achieve approximately 16 VDC.

[BMW850]

I measuring 13,2v between 0 and the entrance of the 7812 the current is to low.
I have the speaker protection tested with the light bulb tester and speaker protection works well.
The speaker protection click after 6 seconds

Rudy

[currentflow]

Originally Posted by BMW850

I measuring 13,2v between 0 and the entrance of the 7812 the current is to low.
I have the speaker protection tested with the light bulb tester and speaker protection works well.

Rudy

I don't think your transformer is adequate. What is its specification?

Can you measure the output from the regulator: a) with the relays on, and b) with the relays off please.