Solved TDA7293 blowing up

[Blueberry5*]

Hi guys and gals, liftime of electronics, found the tda7293,4, exploding caused by stanby and mute, chip manufacturing was changed but datasheet no longer relecrs the changes. The MAX voltages used to be the v+ but now causes the chip to explode, limit the stanby and mute voltage to 5 volts eather with zener diode or resistor devider, before the rc network described, also do not connect 2 chips mute or stanby together as if one chip fails both chips will blow.

 

[HAYK]

The Mute, Standby levels are referenced to standby ground pin1. What level is your pin1?

 

[Blueberry5*]

Ground pins 1 and 4 tied to gtound

 

[Blueberry5*]

Older chips from year 2002, allowed full v+ to standby and mute newer ones tda7294 and tda7293, also good bypassing of v+ and v- using .1 uf ceramic with 10 uf electrolitic. keep feedback components short leads and away from other output signals, resistor body near input side of chip,
Back to standby and mute, look at timing waveform chart, the standby and mute only require 3.5 volts max.in operation voltages in data sheet

 

[profiguy]

Could use an LED forward biased and fed through resistor to limit standby V? That would also provide an indicator for standby. Alternatively, 4 x 1N4148 series would work too if a single zener is more expensive. Does the chip carry any noise into the input stage ie diode noise?

 

[Lee@purenoise]

Ive had lots of trouble with these chips recently. This exact problem. But ive read and watched loads on Fake ones.
Ive just bought 2 from Digikey in America in the hope that they a) wouldn't be fake b) wouldn't blow up.

Ive bought two just in case . The circuit however has a 6v8 zener and currently limiting to 6v7 on probing.

Absolutely scared to plug it all in and see.

Ive tested the resistance between the tda7923's that id bought elsewhere and the legit ones from digikey and there are very large differences

Have you come up with a method of testing this without destroying the IC?

First time posting

long time follower

 

[Mooly]

If a linear PSU is used could you not use a DBT to limit current in the event of a problem? If it is an SMPS then that won't work.

 

[mattbu]

I bought a bunch of TDA7294 last year and give those pins supply + (24Vdc) and they do not blow. First time I built one up I did not include the 10k/22k resistors and they still worked. I later added those resistors.

My experience.