2n6558 alternative?

[ghostman11]

i am trying to repair a scope and i need a 2n6558 transistor but cant find one so does anyone know of a close replacement for it? datasheet here https://www.datasheetarchive.com/2N6558-datasheet.html it would be good if i could this old scope working

 

[alec_t]

A quick google for 'high voltage transistor video' gave several hits, including NTE399. Any good?

 

[ghostman11]

thanks alec i will compare the sheets, not to sure just how crictical a good match is! i didnt think to google the description lol i only did the part number and tried finda chip

 

[KeepItSimpleStupid]

www.littlediode.com has them in stock and their in your neck of the woods. Nice company.

 

[ghostman11]

thanks for the link! i nearly choked tho when i saw the price lol still i would prefer to use the actual part thats in there so i will have to dust off the wallet

 

[dr pepper]

Wow 15 notes for a tranny, I dont spose you'll be wanting to get another couple spare just in case.

What part of the circuit is it out of, if its not one of the y amps or horizontal deflection it may not be that critical.

 

[KeepItSimpleStupid]

At least it's not made of unobtainium. I've used LittleDiode as a supplier before and I'm in the US.

 

[dr pepper]

A mate of mine has a classic 60's plymouth, it has the original radio but it doesnt work as the mixer osc transistor is dead, its one of those really old 4 pin jobs from rca I cant get a replacement at any price, and I couldnt find a suitable equiv.
Mixer oscs are hard to substitute as the device works in different modes.

 

[ghostman11]

unfortunately its for the horizontal tracking i also think there are a number of caps to replace so i am weighing up if it's worth spending the money on as it's not what i would call a great must have scope.
dr pepper whats the transistor number? i have some 4 pin old ones from a batch of stuff i got from a ex radio ham guy there was all kinds of odd stuff in it

 

[dr pepper]

I cant remember but I'll have a look at the schematic when I get back to my home lab, there was also a few equivs shown on the schematic which also are obsolete.

RCA had an issue with the sticky compound they put in to hold the device togther, some of themreacted with the substrate and etched through it.

 

[dr pepper]

Found it.

Its a rca sk3018

I beleive they were american made, I spose RCA gives that away.

 

[KeepItSimpleStupid]

Hurry: **broken link removed**

 

[dr pepper]

Well spotted.

For some reason I didnt think they were germanium.

 

[KeepItSimpleStupid]

Relatively cheap too. My father used to bring home car radios from coworkers to repair, so I remember lots of the five transistor or so radios. I was young enough to help meaning I could find a bad transistor for the most part, but I could have been 10 years old. There are still some car radios in the house, but I have no idea of their status.

 

[dr pepper]

I tried a silicon at the time, but couldnt get it to work, the mixer/osc as you probably know operates in its non linear part of the curve, so biasing is critical.

I spose I could have taken out one of the sk's that was being used as an audio pre amp, put that in the mixer osc position and replaced it with a solicon.

I spent that long messing with that thing I dont think I'd want to see it again.