What to replace KTD718 and KTB688's with?

[spooney]

I've been searching like crazy and have been unable to find an answer to this question.I have a 4 channel alpine with one bad channel.The complementary KTD718 and KTB688's are both done for.I have yet to find a clear answer as to what components might replace these parts?Do I simply need to find bi -polar audio output transistors with the same or higher maximum ratings?

[iUSERTLO72p]

Hi there, Data sheets will help you match. Here they are. PDF's in a Archive.

Cheers iUSERTLO72p

[iUSERTLO72p]

t'other

Hope they help

[Perry Babin]

Most of the distributors in the US are using the 2S prefix instead of the KT prefix. When you need a KTD718, search for 2SD718. The datasheet for the 2SD718 says it's an 8 amp transistor. The KEC datasheet says it's a 10 amp transistor. Otherwise, the specs are essentially the same. Generally, when I order the 2S parts, I get the KEC transistors.

Whenever you use the 2S prefix for a KEC part, you need to compare datasheets. Often, they are identical but sometimes, they are not. Sometimes, they're a completely different component.

If you want to get the original parts, order them from pacparts.com. They have one in stock but they'd have to order the other one. They are ~$11 each.

There are a couple of sellers on aBay that have the 2S versions for sale.

If the amp uses a screw to clamp the transistor (through an insulated hole in the tab), there aren't many options.

[grjr]

You could also trying replacing the outputs with cross reference parts from fairchild http://www.fairchildsemi.com/crossref/crossrefSearch.do

I have an amplifier that uses the same output transistors and will be trying to replace them with parts from fairchild soon.

[spooney]

Thank you guys for the help.The fairchild parts are readily available and appear to be better than the originals.

[durwood]

Thread revival.

Have an amp here with a blown output using the KTD718 O/KTB688 O. Since these parts are hard to find and it's not worth paying a premium for them I have 3 options. I am leaning towards the 2STW4468 O/2STW1695 due to price @digikey and the value of this amp, however the FJA4313 O/FJA4313 O has a bit closer specs and more current capability.

Anyone else have any opinions before I order the 2STW4468/2STW1695?

						KTD718 O	2STW4468	FJA4310 O	FJA4313 O
Price						N/A		0.79		1.59		1.55
Source								Digikey		Mouser		Mouser
 CHARACTERISTIC  	 	SYMBOL  	 UNIT  	-	-	-	-
 Collector-Base Voltage  	Vcb	 V  	 120  		200		200		250
 Collector-Emitter Voltage  	Vce	 V  	 120  		140		140		250
 Emitter-Base Voltage  		Veb	 V  	 5  		6		6		5
 Collector Current  		Ic	 A  	 10  		10		10		17
 Base Current  			IB	 A  	 1.0  				1.5		1.5
 Collector Power Dissipation 	Pc  	 W  	 80  		100		100		130
 Junction Temperature  	 	Tj  	 °C  	 150  		150		150		150
 
						
 ELECTRICAL CHARACTERISTICS (Ta=25°C)  					
 CHARACTERISTIC  	 SYMBOL  					
 Collector Cut-off Current  	 leno  	uA	10		0.1		10		5
 Emitter Cut-off Current  	 lEBO  	uA	10		0.1		10		5
 C-E Breakdown Voltage  	 Vbrceo V	120		140		140		250
 DC Current Gain  	 	hfe  		80-160		70-140		70-140		80-160
 C-E Sat Voltage  	 	VCE(sat)V	2		0.5-0.7		0.5		0.4-3
 Base-Emitter Voltage  		Vbe	V	1.5		1.3				1.5
 Transition Frequency  	 	h  	MHZ	12		20		30		30
 Collector Output Capacitance  	 Cob  	pF	170		150		250		200

[Perry Babin]

I use the FJA4213 and FJA4313 as replacements for all of the transistors like this. There has never been a problem with them.