Need advice for connecting amp to one transformer

[elchiriri]

Hi.
Im new one here and i saw a thread about connecting one transformer to two seperate amps. Im in similar position so here it is... the transformer originaly IS from an old akai amp it has 24-0-24, 2x25w, 220v in, 2 capacitors were 4700mf 50v on the original pcb. The amps are both TDA7294 100w 36v -/+.
They are seperated, on two PCB's and have tree power input connections. For the one amp and the transformer conection is fine i know that much. Problem for me is the second amp. I was thinking putting one 24v wire on one amp and the other 24v wire on the other amp and bridging the ground/negative between amps with wire. The amps have 2200mf 50v caps. And image provided already connected. But not powered up yet.

 

[cpt_paranoia]

the transformer originaly IS from an old akai amp it has 24-0-24, 2x25w, 220v in, 2 capacitors were 4700mf 50v on the original pcb. The amps are both TDA7294 100w 36v -/+

The TDA7294 needs complementary DC supplies (+ve & -ve). You will need to rectify the transformer output. It's not clear if your existing supply does that. See:

http://www.interfacebus.com/Glossary-of-Terms-full-wave-bridge-rectifier-circuit.html

But the 25+25W transformer rating looks under-rated for powering two 100W amps.

Since none of your connection are labelled, I have no idea how you have wired up your circuit.

 

[elchiriri]

The TDA7294 needs complementary DC supplies (+ve & -ve). You will need to rectify the transformer output. It's not clear if your existing supply does that. See:

http://www.interfacebus.com/Glossary-of-Terms-full-wave-bridge-rectifier-circuit.html

But the 25+25W transformer rating looks under-rated for powering two 100W amps.

Since none of your connection are labelled, I have no idea how you have wired up your circuit.

The black is minus, blue plus x2 and the fat blue is bridged minus, its ok if it is underrated i dont have big speakers

 

[elchiriri]

The black is minus, blue plus x2 and the fat blue is bridged minus, its ok if it is underrated i dont have big speakers

I have read somewhere the doesnt matter if those double positive line are connected V+ on V- and vice versa the rectifier will correct that

 

[elchiriri]

Checked

 

[cpt_paranoia]

have read somewhere the doesnt matter if those double positive line are connected V+ on V- and vice versa the rectifier will correct that

The TDA7924 needs both supplies. I have no idea what amplifier module you have, or what circuitry it has surrounding the amp IC.

Currently, you appear to have just one supply connected. You still haven't identified the nature of your salvaged power supply, and whether it is merely a transformer, or whether it includes rectification.

I would go and read the data sheet for the amp, and for your amp module.

 

[elchiriri]

Its similar circuit but you can see the rectifiers on the first image between caps. The tranformer is original for this model of amp i've just removed the pcb because its realy old and cant find new parts specialy the stk chip.

 

[elchiriri]

I just want to know wil ithe transformer works safetly connected like in the first image.

 

[cpt_paranoia]

I can see some components, including what appear to be bridge rectifiers, but, without a circuit diagram, I can't see how anything is connected, from that photo, sorry.

 

[cpt_paranoia]

Checked

This PCB appears to be nothing like the populated one in your first picture. What did you intend it to show?

 

[elchiriri]

This PCB appears to be nothing like the populated one in your first picture. What did you intend it to show?

The connections v+ v- and ground.

Nevermind ill connect them with bridged ground and power it on. If it blowns it blowns.

 

[cpt_paranoia]

The connections v+ v- and ground.

Nevermind ill connect them with bridged ground and power it on. If it blowns it blowns.

Well of course there are v+, v- and gnd. And of course you can connect the power supplies to both amp modules (your 'bridged ground').

The question is what exactly are you trying to connect to your modules, in terms of power supply? Is it DC? Or is it AC direct from the transformer? You appear to only have connected one supply, and gnd (you appear to have only connected two wires) to what might be the power pins.

 

[elchiriri]

Oh, ok i understand. Yes its AC 24v from transformer. What im trying to connect is one amp (with rectifiers on both) on AC 24v, ground directly to one amp from tansformer to that amp, the other 24v AC to the other amp and negative connected between amps. The transformer is center taped so one blue wire is that center taped wire. Will post a picture of the connection and parts. Now is connected one amp only. Those connection on the treansformer are the output 3 wires.