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D.A.S.
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https://datasheetspdf.com/pdf/570328/Motorola/MC1314P/1. For the quad VCA obsolete chip.

Your schematic on the surface looks ok.

Did it overheat immediately? Polarity correct on Vcc, Gnd

https://4donline.ihs.com/images/VipMasterIC/IC/MOTO/MOTOS12755/MOTOS12755-1.pdf?hkey=D9A213CC6FEE7D103EF6B88F2AEB20B8 enter link description here

enter image description here

Beware the pins are shown upside down in the block diagram!

ALSO your cap polarity is backwards

which shorts out the cap!! And may induce excessive DC bias current (?)

why did it blow?

tl;dr = e-caps reversed, causing caps to conduct DC with low ESR, causing differential input Vbe of NPN’s to go negative with 0Vin and +ve emitters, causing Reb=~<10 ohms, causing avalanche punch-thru, causing Vce punchthru and unlimited current across conducting junctions, causing explosive results

  • with >10W/sqmm causing a crater in the epoxy but perhaps nitnot sustained long enough to blow the e-caps which might have been a bigger explosion with toxic smoke , And;It enough to exceed say a battery thermal runaway which would result in a bigger problem.

  • most BJT’s have a -5V limit for Vbe.

  • many e-caps can tolerate -10% of the forward rated voltage for a limited period.

  • when you aren’t sure try to have current limiting for the size of the junction, BJT or IC or PCB.

  • use a passive RC filter or PTC oxide resistor for the safe limit might work if it heats up faster and rises in R faster than the junction,

  • but not in this case.

  • an active current limiter is pretty easy to setup for experimentation or use an LDO sized appropriately, e.g. LM317

Reading material

https://www.onsemi.com/pub/Collateral/AN1628-D.PDF

https://datasheetspdf.com/pdf/570328/Motorola/MC1314P/1. For the quad VCA obsolete chip.

Your schematic on the surface looks ok.

Did it overheat immediately? Polarity correct on Vcc, Gnd

https://4donline.ihs.com/images/VipMasterIC/IC/MOTO/MOTOS12755/MOTOS12755-1.pdf?hkey=D9A213CC6FEE7D103EF6B88F2AEB20B8 enter link description here

enter image description here

Beware the pins are shown upside down in the block diagram!

ALSO your cap polarity is backwards

which shorts out the cap!! And may induce excessive DC bias current (?)

why did it blow?

tl;dr = e-caps reversed, causing caps to conduct DC with low ESR, causing differential input Vbe of NPN’s to go negative with 0Vin and +ve emitters, causing Reb=~<10 ohms, causing avalanche punch-thru, causing Vce punchthru and unlimited current across conducting junctions, causing explosive results

  • with >10W/sqmm causing a crater in the epoxy but perhaps nit sustained long enough to blow the e-caps which might have been a bigger explosion with toxic smoke , And;It enough to exceed say a battery thermal runaway which would result in a bigger problem.

  • most BJT’s have a -5V limit for Vbe.

  • many e-caps can tolerate -10% of the forward rated voltage for a limited period.

  • when you aren’t sure try to have current limiting for the size of the junction, BJT or IC or PCB.

  • use a passive RC filter or PTC oxide resistor for the safe limit might work if it heats up faster and rises in R faster than the junction,

  • but not in this case.

  • an active current limiter is pretty easy to setup for experimentation or use an LDO sized appropriately, e.g. LM317

Reading material

https://www.onsemi.com/pub/Collateral/AN1628-D.PDF

https://datasheetspdf.com/pdf/570328/Motorola/MC1314P/1. For the quad VCA obsolete chip.

Your schematic on the surface looks ok.

Did it overheat immediately? Polarity correct on Vcc, Gnd

https://4donline.ihs.com/images/VipMasterIC/IC/MOTO/MOTOS12755/MOTOS12755-1.pdf?hkey=D9A213CC6FEE7D103EF6B88F2AEB20B8 enter link description here

enter image description here

Beware the pins are shown upside down in the block diagram!

ALSO your cap polarity is backwards

which shorts out the cap!! And may induce excessive DC bias current (?)

why did it blow?

tl;dr = e-caps reversed, causing caps to conduct DC with low ESR, causing differential input Vbe of NPN’s to go negative with 0Vin and +ve emitters, causing Reb=~<10 ohms, causing avalanche punch-thru, causing Vce punchthru and unlimited current across conducting junctions, causing explosive results

  • with >10W/sqmm causing a crater in the epoxy but perhaps not sustained long enough to blow the e-caps which might have been a bigger explosion with toxic smoke , And;It enough to exceed say a battery thermal runaway which would result in a bigger problem.

  • most BJT’s have a -5V limit for Vbe.

  • many e-caps can tolerate -10% of the forward rated voltage for a limited period.

  • when you aren’t sure try to have current limiting for the size of the junction, BJT or IC or PCB.

  • use a passive RC filter or PTC oxide resistor for the safe limit might work if it heats up faster and rises in R faster than the junction,

  • but not in this case.

  • an active current limiter is pretty easy to setup for experimentation or use an LDO sized appropriately, e.g. LM317

Reading material

https://www.onsemi.com/pub/Collateral/AN1628-D.PDF

added 1096 characters in body; added 4 characters in body; added 72 characters in body
Source Link
D.A.S.
  • 148k
  • 3
  • 56
  • 190

https://datasheetspdf.com/pdf/570328/Motorola/MC1314P/1. For the quad VCA obsolete chip.

Your schematic on the surface looks ok.

Did it overheat immediately? Polarity correct on Vcc, Gnd

https://4donline.ihs.com/images/VipMasterIC/IC/MOTO/MOTOS12755/MOTOS12755-1.pdf?hkey=D9A213CC6FEE7D103EF6B88F2AEB20B8 enter link description here

enter image description here

Beware the pins are shown upside down in the block diagram!

ALSO your cap polarity is backwards

which shorts out the cap!! And may induce excessive DC bias current (?)

why did it blow?

tl;dr = e-caps reversed, causing caps to conduct DC with low ESR, causing differential input Vbe of NPN’s to go negative with 0Vin and +ve emitters, causing Reb=~<10 ohms, causing avalanche punch-thru, causing Vce punchthru and unlimited current across conducting junctions, causing explosive results

  • with >10W/sqmm causing a crater in the epoxy but perhaps nit sustained long enough to blow the e-caps which might have been a bigger explosion with toxic smoke , And;It enough to exceed say a battery thermal runaway which would result in a bigger problem.

  • most BJT’s have a -5V limit for Vbe.

  • many e-caps can tolerate -10% of the forward rated voltage for a limited period.

  • when you aren’t sure try to have current limiting for the size of the junction, BJT or IC or PCB.

  • use a passive RC filter or PTC oxide resistor for the safe limit might work if it heats up faster and rises in R faster than the junction,

  • but not in this case.

  • an active current limiter is pretty easy to setup for experimentation or use an LDO sized appropriately, e.g. LM317

Reading material

https://www.onsemi.com/pub/Collateral/AN1628-D.PDF

https://datasheetspdf.com/pdf/570328/Motorola/MC1314P/1. For the quad VCA obsolete chip.

Your schematic on the surface looks ok.

Did it overheat immediately? Polarity correct on Vcc, Gnd

https://4donline.ihs.com/images/VipMasterIC/IC/MOTO/MOTOS12755/MOTOS12755-1.pdf?hkey=D9A213CC6FEE7D103EF6B88F2AEB20B8 enter link description here

enter image description here

Beware the pins are shown upside down in the block diagram!

ALSO your cap polarity is backwards

which shorts out the cap!! And may induce excessive DC bias current (?)

https://datasheetspdf.com/pdf/570328/Motorola/MC1314P/1. For the quad VCA obsolete chip.

Your schematic on the surface looks ok.

Did it overheat immediately? Polarity correct on Vcc, Gnd

https://4donline.ihs.com/images/VipMasterIC/IC/MOTO/MOTOS12755/MOTOS12755-1.pdf?hkey=D9A213CC6FEE7D103EF6B88F2AEB20B8 enter link description here

enter image description here

Beware the pins are shown upside down in the block diagram!

ALSO your cap polarity is backwards

which shorts out the cap!! And may induce excessive DC bias current (?)

why did it blow?

tl;dr = e-caps reversed, causing caps to conduct DC with low ESR, causing differential input Vbe of NPN’s to go negative with 0Vin and +ve emitters, causing Reb=~<10 ohms, causing avalanche punch-thru, causing Vce punchthru and unlimited current across conducting junctions, causing explosive results

  • with >10W/sqmm causing a crater in the epoxy but perhaps nit sustained long enough to blow the e-caps which might have been a bigger explosion with toxic smoke , And;It enough to exceed say a battery thermal runaway which would result in a bigger problem.

  • most BJT’s have a -5V limit for Vbe.

  • many e-caps can tolerate -10% of the forward rated voltage for a limited period.

  • when you aren’t sure try to have current limiting for the size of the junction, BJT or IC or PCB.

  • use a passive RC filter or PTC oxide resistor for the safe limit might work if it heats up faster and rises in R faster than the junction,

  • but not in this case.

  • an active current limiter is pretty easy to setup for experimentation or use an LDO sized appropriately, e.g. LM317

Reading material

https://www.onsemi.com/pub/Collateral/AN1628-D.PDF

added 111 characters in body
Source Link
D.A.S.
  • 148k
  • 3
  • 56
  • 190

https://datasheetspdf.com/pdf/570328/Motorola/MC1314P/1. For the quad VCA obsolete chip.

Your schematic on the surface looks ok.

Did it overheat immediately? Polarity correct on Vcc, Gnd

https://4donline.ihs.com/images/VipMasterIC/IC/MOTO/MOTOS12755/MOTOS12755-1.pdf?hkey=D9A213CC6FEE7D103EF6B88F2AEB20B8 enter link description here

enter image description here

Beware the pins are shown upside down in the block diagram,!

ALSO your cap polarity is backwards

which shorts out the cap!! And may induce excessive DC bias current (?)

https://datasheetspdf.com/pdf/570328/Motorola/MC1314P/1. For the quad VCA obsolete chip.

Your schematic on the surface looks ok.

Did it overheat immediately? Polarity correct on Vcc, Gnd

https://4donline.ihs.com/images/VipMasterIC/IC/MOTO/MOTOS12755/MOTOS12755-1.pdf?hkey=D9A213CC6FEE7D103EF6B88F2AEB20B8 enter link description here

enter image description here

Beware the pins are shown upside down in the block diagram,

https://datasheetspdf.com/pdf/570328/Motorola/MC1314P/1. For the quad VCA obsolete chip.

Your schematic on the surface looks ok.

Did it overheat immediately? Polarity correct on Vcc, Gnd

https://4donline.ihs.com/images/VipMasterIC/IC/MOTO/MOTOS12755/MOTOS12755-1.pdf?hkey=D9A213CC6FEE7D103EF6B88F2AEB20B8 enter link description here

enter image description here

Beware the pins are shown upside down in the block diagram!

ALSO your cap polarity is backwards

which shorts out the cap!! And may induce excessive DC bias current (?)

added 312 characters in body; added 87 characters in body; added 60 characters in body
Source Link
D.A.S.
  • 148k
  • 3
  • 56
  • 190
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Source Link
D.A.S.
  • 148k
  • 3
  • 56
  • 190
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