2sc756

[jblmar]

Hello,
What would be a suitable replacement for the old 2SC756 transistor found on the 5000A F-1040 board.

Ron

 

[merrylander]

Go to www.onsemi.com and enter the number in their search function.

 

[EchoWars]

What are the transistor specs?

What is the case style?

 

[LBPete]

Go to www.onsemi.com and enter the number in their search function.

Careful, that OnSemi cross reference function is not always trustworthy. I've seen it make big obvious mistakes.

- Pete

 

[MarkMeyer]

Careful, that OnSemi cross reference function is not always trustworthy. I've seen it make big obvious mistakes.

- Pete

You got that right. I found out right away when I started working on my AU-717 that NONE of the cross reference charts can be trusted.
They do come in handy, but only to use as a starting point for comparing the specs themselves of the parts in question. Half the time, I found better matches on my own.

EW is right; especially if a person is new to this, they should start early-on to learn about what the specs and style of parts are, rather than to trust any "suggested" part number.

 

[jblmar]

What are the transistor specs?

What is the case style?

Hi Glen,
It's the old, round metal case.
I'll take a few shots of it this evening.

Ron

 

[jpdylon]

I'm not sure that the C756 sony transistor in the 5000a is really a 2sc756.

Looking at the specs

100v
4a
10w
65mhz
hfe ~100

There's no way that little TO-5 flying saucer can dissipate 10 watts of power and handle 4 amps of current!

Its used as the class a driver in the 5000a. What symptom are you experiencing that makes it believed to be bad? Just curious.

 

[jblmar]

I'm not sure that the C756 sony transistor in the 5000a is really a 2sc756.

Looking at the specs

100v
4a
10w
65mhz
hfe ~100

There's no way that little TO-5 flying saucer can dissipate 10 watts of power and handle 4 amps of current!

Its used as the class a driver in the 5000a. What symptom are you experiencing that makes it believed to be bad? Just curious.

I was thinking the same as you. Too small for the job.
The amp is a fellow AK members. I found one output transistor shorted on the left channel. The fuse blew on that channel when powered up. The output transistors had only the mica insulators. No heat sink compond. I figured that the amp was tampered with at sometime.

One 2SC756 measured differently from one channel to another. All other trs, including the other 756s measured close or the same. I'll have to remove the one 756 for more accurate measurements.
I figured that the 756 may be difficult to obtain, so I got lazy.

Ron

 

[jpdylon]

They are difficult to find. I think I have a spare from a parts machine if you need one. I have a spare 1040 board with some parts left on it, so let me know if there's anything else you might need for the set.

 

[jblmar]

Thanks, Jordan.:thmbsp:

Ron

 

[Nakdoc]

The 2SA756 2SC756 transisitors are drivers, not outputs! The outputs are TO-3. These are TO-92 (IIRC). 2SD1138 or 2SC2497A are listed as subs. I would consider a TO-220 case, and there are hundereds to choose from. You'd have to fool around with the thermal bias diode mount.

 

[jblmar]

The 2SA756 2SC756 transisitors are drivers, not outputs! The outputs are TO-3. These are TO-92 (IIRC). 2SD1138 or 2SC2497A are listed as subs. I would consider a TO-220 case, and there are hundereds to choose from. You'd have to fool around with the thermal bias diode mount.

Hi Nak,
Yes, the 756 are not outputs but driver transistiors.
One of the output transistors (IIRC 2SC118-TO-3 case) was shorted. The 456are the driver transistors mounted on the F-1040 board. The later boards used TO-3 transistors in place of the 756 which leads me to believe that the 756 use not robust enough.
It would be difficult to mount a TO-3 in place of the 756.

Ron