point to point?

[darkczar]

I'm looking for a little advice. I bought two TDA2050 kits from Maplin's (like Radio Shack) and soldered everything together. I got some music out of it, but a lot of background noise between songs. It sounded like the ocean, not a constant hum. I decided to take the parts off the PCB's and solder point to point, because I thought maybe my soldering on the PCB was faulty. (It was my first time soldering anything electronic like that.) I think I compromised one of the boards that came with the two kits, when I took the parts off. I tried to solder point to point, but the parts were unsalvagable, kinda. I ordered what I think should be replacements for all the parts in the kit. I'm ready to have a second go at it.

Should I solder point to point? Is there a source for boards for TDA2050? Can I use some kind of generic board?

Any advice would be appreciated. thanks.

[sregor]

AFAIK, any Gainclone PCB for an LM1875 should work with the TDA2050. Compare the recommended values from the data sheets, but I think they are pretty close. YMMV.
Good luck with it. BTW, the case of the chip is connected to the negative voltage in a plus/minus supply circuit. Be careful when attaching it to heat sinks.

[darkczar]

Cool - thanks.

Should I be insulating the heatsink from the chip with some grease or something? I just screwed the heatsink to the chip. I think it was causing problems.

I saw this last night:

DIY TDA2050 Hi-Fi Chip Amplifier (chipamp)

This one uses a "proto-board". I might try that, since I could spread out a little and avoid shorting out with my poor soldering.

Should I be using big capacitors between my bridge rectifiers and the amplifier circuits? I've got one capacitor in parallel at the unit's power switch. That eliminated the pop on start-up.

Hopefully I can put it together this weekend.

[sregor]

The proto-board looks very reasonable. If you look at his pictures - you will notice that the chip is mounted to the heat sink with a mica insulator and heatsink grease, as well as an insulated washer for the mounting screw. Highly recommended. One caveat - make sure there are no burrs or metal pieces which might short through the mica. The only alternative is to isolate the heat sink, as it would have the negative voltage on it. This has been done, but most people consider it not worth the effort or risk. If you make a single supply design (capacitor coupled with the output sitting at half the supply voltage), you can get away with it as the negative side of the chip would be connected to ground. The proto board link has good information on grounding and other tips to make a good amp. Lastly - it is possible to set up the amp without a heatsink, but make sure you put i on the heat sink before any hooking it to a speaker or test load. Good luck with it.

[darkczar]

Hi - thanks for the reply. I've been trying to read more about all of this stuff, but it doesn't seem to get any less confusing.

I think I had my heatsinks isolated. They were not touching the chassis or anything, except the chip. I'm hoping I got better quality parts this time around.

I grew up in Lexington MA, btw.