Hi all.
My girlfreind decided to chuck out her old Phillips all in one cheapo Hi-Fi.
I decided to take a look inside and see what was useful for salvage. I noticed the amp was chip based using the TDA7269SA and has a nice heat sink and good size transformer. Basically everything I need to knock up a hardwired 10w stereo amp is there. Big smoother caps, resistors etc. I want to build this into a little power amp as a starter project and an introduction to building chip amps. The best thing is I have all the parts I need except a case, so if it goes bang I haven't lost anything. The datasheet even has a PCB layout! 🙂
I'll be following the datasheet to keep things easy.
One thing I really need help with is the transformer, its mounted to the PCB. I can see the input pins as they are marked on the board, however the outputs are not marked. I need to know what Im dealing with as this is the first part in the chain. It has a part number on it: DB-E166-3382A. Google shows nothing.
There are 8 pins on the output. How do I safely test the trafo with my meter to find put whats going on?
Also, if anyone has any experience with this family of chips can you advise what kind of sound these things produce? Once I get it working I can look at tweaks perhaps.
Rgds,
Mike.
My girlfreind decided to chuck out her old Phillips all in one cheapo Hi-Fi.
I decided to take a look inside and see what was useful for salvage. I noticed the amp was chip based using the TDA7269SA and has a nice heat sink and good size transformer. Basically everything I need to knock up a hardwired 10w stereo amp is there. Big smoother caps, resistors etc. I want to build this into a little power amp as a starter project and an introduction to building chip amps. The best thing is I have all the parts I need except a case, so if it goes bang I haven't lost anything. The datasheet even has a PCB layout! 🙂
I'll be following the datasheet to keep things easy.
One thing I really need help with is the transformer, its mounted to the PCB. I can see the input pins as they are marked on the board, however the outputs are not marked. I need to know what Im dealing with as this is the first part in the chain. It has a part number on it: DB-E166-3382A. Google shows nothing.
There are 8 pins on the output. How do I safely test the trafo with my meter to find put whats going on?
Also, if anyone has any experience with this family of chips can you advise what kind of sound these things produce? Once I get it working I can look at tweaks perhaps.
Rgds,
Mike.
Can anyone tell me how to measure the trafo without killing myself? I'll get some pics on here today. Thnx 🙂
Hi,
be patient.
First throw away the chipamp. it's the sort of thing you will find inside those cheap computer monitors and they will claim 500W PMPO.
10W @ 10% distortion is going to be unbearable.
A 10W + 10W (exaggerated claim) with a big transformer! How big?
It might make a good basis for a pre-amp.
Disconnect the transformer from the rectifier/s.
Measure the Vac from each set of windings. With 8 tappings this is going to take a while to sort out.
Better to set up through a light bulb tester in case you short out an output.
Could 4 of the tappings be the 110/120 + 110/120 Vac primaries?
That would leave 4 tappings for a dual secondary to measure up.
be patient.
First throw away the chipamp. it's the sort of thing you will find inside those cheap computer monitors and they will claim 500W PMPO.
10W @ 10% distortion is going to be unbearable.
A 10W + 10W (exaggerated claim) with a big transformer! How big?
It might make a good basis for a pre-amp.
Disconnect the transformer from the rectifier/s.
Measure the Vac from each set of windings. With 8 tappings this is going to take a while to sort out.
Better to set up through a light bulb tester in case you short out an output.
Could 4 of the tappings be the 110/120 + 110/120 Vac primaries?
That would leave 4 tappings for a dual secondary to measure up.
Hi Andrew,
I really dont know the specs of the transformer, as I said I cant find any info on the net. It seems to have quite a few outputs and I just need to know what they are so I can find out which to use on the chip.
Its a square type trafo with a metal frame. On one side there are inputs for the mains marked: Fuse - 0 - 127 - 230 - 240v. On the opposite side there are 8 pins but these are not marked. The trafo is about 5 x 4 cm.
I just thought I could try and knock up a little amp as a learning project really, just for the experience. I dont expect it to produce sublime sound quality. I just thought I could practice on this befor I do something more serious.
Should I put some pics up so people can get a better idea of what i'm dealing with?
I really dont know the specs of the transformer, as I said I cant find any info on the net. It seems to have quite a few outputs and I just need to know what they are so I can find out which to use on the chip.
Its a square type trafo with a metal frame. On one side there are inputs for the mains marked: Fuse - 0 - 127 - 230 - 240v. On the opposite side there are 8 pins but these are not marked. The trafo is about 5 x 4 cm.
I just thought I could try and knock up a little amp as a learning project really, just for the experience. I dont expect it to produce sublime sound quality. I just thought I could practice on this befor I do something more serious.
Should I put some pics up so people can get a better idea of what i'm dealing with?
PICTURES
The hi-fi this came from didn't sound too bad, it wasn't unbearable but it wasn't amazing either. My hunch is that the chip built hardwired and in a much simpler circuit - ie: no other cpu's lcd's etc to introduce noise - it might sound reasonable. Even if it sounds a pile of crud its a useful project for learning and practice.
Mike.
The hi-fi this came from didn't sound too bad, it wasn't unbearable but it wasn't amazing either. My hunch is that the chip built hardwired and in a much simpler circuit - ie: no other cpu's lcd's etc to introduce noise - it might sound reasonable. Even if it sounds a pile of crud its a useful project for learning and practice.
Mike.
I've been looking at the schematics in the datasheet and I fancy the split supply version as it seems simpler with less connections and parts. Even so, the circuit looks quite complex and I think I can simplify it so I downloaded ExpressPCB/SCH. I've never drawn a schematic before so can anyone give any advice please? Can this circuit be simplified?
The plan is to strip the required parts off the PCB - Trafo, chip, caps and resistors and recycle them. Maybe I'm better off using veroboard rather than attempting a hardwired chip amp. It looks like the external components on this chip are too numerous to warrant it.
Any suggestions please?
The plan is to strip the required parts off the PCB - Trafo, chip, caps and resistors and recycle them. Maybe I'm better off using veroboard rather than attempting a hardwired chip amp. It looks like the external components on this chip are too numerous to warrant it.
Any suggestions please?
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