Pioneer DM-40 PC Speakers Repair Help

[g1]

Do i test continuity with it?

Not continuity. You need to measure the DC voltages listed in post #11.

[KnightRyda]

Probably a silly question but in the diagram is shows the pin on the far left when orientated upright as pin one and the pin that isn't as long as pin 2. But on the actually chip the left most pin is the long one as shown in one of the photos. Can i confirm that pin 1 is the far left pin?

[J M Fahey]

Pins are bent in a 3D pattern to make PCB design easier (to separate solder pads somewhat) so they appear long or short depending on viewing angle, but the sequence does not change.

As shown, leftmost is Pin 1:



As a side note: I am against replacing parts at random but here we have NO schematic and most likelybthat Chipampis damaged (post measured voltages anyway) so I suggest you order one anyway.

In found only 16 left at Mouser 2 days ago and they warn about 40 week factory lead time.

Given they are only 5 bucks something, I would order one today.

Remember we are in the middle of a semiconductor shortage crisis and Chipamps are NOT a priority.

Delayed 10 million unit orders for the Automotive industry are sucking all factories dry.

[KnightRyda]

Ok thanks for your help. I assumed as much but thought i would double check. I wish it was only $5 but will be $30-$35 for me living in Aus. But ill give it a test and then see how we go. I have been watching availability though.

[KnightRyda]

Alright i tested pins 3,6 and got no reading. Same with 2,4.

[g1]

Where are you placing your black probe when you do those measurements? Pin9 of the TDA is ground so you can use that as a ground. Or make sure what you are using as ground measures 0 ohms to pin9.

[KnightRyda]

I was using pin 9 at ground but i checked again and im getting some reading now. When having on the 20V setting i got 0.3 for 3,6 and 0.3 for 2 and 0.1 for 4. Not sure why i didnt get a reading previously.

[The Dude]

If those readings are correct, you have no power to the IC. Check directly at the power supply. There is a 3 pin connector on the supply with red, blue, and black wires. Check right at that connector. Put black probe at the black wire and measure to each side (red and blue). What do you have for voltages there?

[KnightRyda]

Im a little confused. There shouldnt be any power going to the IC because you said to disconnect everything right?

[The Dude]

No. We said disconnect the speakers only. You can't take voltage measurements with power disconnected.

[KnightRyda]

On the 20V setting pins 3,6 are getting 15.2, pin 2 is getting 15.1 and 4 is getting 0.3

[The Dude]

I'll assume pin 6 is negative, so supply rails are good. Pin 2 output is full rail and the IC is most likely shorted. At this point, I would just go ahead and replace the output IC. Be careful not to tear out through hole connections on the IC pins. It's probably best to cut the legs and remove them one at a time unless you have a good solder sucking tool.

[KnightRyda]

Ok thanks again for your help. I know it must have felt annoying dealing with me but i really do appreciate your help. Time to go order a new one.

[g1]

After installing the new IC, do not connect any speakers till you verify there are no DC voltages on any wires that will go to the speakers.
And while you are waiting for the part, check the resistance of the speaker that had the cone pushing out. And see if the cone moves freely by pushing on it gently with your hand.

[The Dude]

FWIW: Digikey has them in stock, too. You'll have to check, but possibly lower shipping cost?

https://www.digikey.com/en/products/...TDA7265/715877

Or maybe here in Australia?

https://au.element14.com/search?st=tda7265