Help substituting avalanche diode

[Bibdid]

repairs on an old CRT tv from the 80s that blew a flyback have led me to this diode which is reading near 0 in both directions. The diode is marked as an R2KY avalanche diode but is no longer manufactured.

I am fairly new to the world of electronics, could anyone help me source a suitable modern-day equivalent diode?


The datasheet of the diode can be found from
https://datasheetspdf.com/pdf/220430...ctorInc/R2KY/1

many thanks : )

[stj]

Re: Help substituting avalanche diode

do you have a schematic to show where it was used?

[R_J]

Re: Help substituting avalanche diode

You can get one from here: https://www.ebay.co.uk/itm/R2KY-ZENE...-/192164981448

[stj]

Re: Help substituting avalanche diode

NIKKO??? good luck.
that guy is down the road - he is hardly open and often exagerates stock.
but you may get lucky.

[Bibdid]

Re: Help substituting avalanche diode

do you have a schematic to show where it was used?

unfortunately not. The tv is a Mitsubishi ct 2043B although it seems to be really obscure.


The diode is connected to a voltage regulator. I will have a look at making a schematic in the next few days : )

[Bibdid]

Re: Help substituting avalanche diode

You can get one from here: https://www.ebay.co.uk/itm/R2KY-ZENE...-/192164981448

Thanks, although I am a little worried that he states the part is 160v 1a as I'm sure the part should be 120v 2A?

I may give it a go though.

[petehall347]

Re: Help substituting avalanche diode

unfortunately not. The tv is a Mitsubishi ct 2043B although it seems to be really obscure.


The diode is connected to a voltage regulator. I will have a look at making a schematic in the next few days : )

what is the board number ? will be something like vestel------- or maybe Haier -----
there is a schematic but asks to sign up . http://freebodydiagram.archivioprimo...our-television

[R_J]

Re: Help substituting avalanche diode

I believe it is just for over voltage protection on the +112 volt line to the horz. output section. I would replace the low voltage/capacity electrolytics in the primary, If they are bad the power supply might not regulate properly, it could also be bad caps on that B+ 112v line, If the caps go open the voltage can go up. You should be able to use the NTE570
Check the schematic for the CT-2153

[Bibdid]

Re: Help substituting avalanche diode

what is the board number ? will be something like vestel------- or maybe Haier -----
there is a schematic but asks to sign up . http://freebodydiagram.archivioprimo...our-television

That looks promising but the site seems to be very shady. Relinks me to scam sites.

I have attached some board model/serial numbers although it seems very obscure.

[Bibdid]

Re: Help substituting avalanche diode

I believe it is just for over voltage protection on the +112 volt line to the horz. output section. I would replace the low voltage/capacity electrolytics in the primary, If they are bad the power supply might not regulate properly, it could also be bad caps on that B+ 112v line, If the caps go open the voltage can go up. You should be able to use the NTE570
Check the schematic for the CT-2153

Thanks for the help. I measured the capacitance and esr of a few capacitors around that area and they are way out of spec. Is it possible that these caps took out the flyback? I know this tv has had a very hard life and the flyback exploded somewhat violently, with resin being thrown out a fair distance onto the board.

As for the schematic, is there any reason you recommend the CT-2153 over others, just out of curiosity?

[petehall347]

Re: Help substituting avalanche diode

. cant make sense out of the board numbers yet .. maybe there are more numbers or a sticker

[petehall347]

Re: Help substituting avalanche diode

this looks like it ...

[R_J]

Re: Help substituting avalanche diode

It is possible that the power supply started to output a higher voltage causing the flyback to operate at a higher voltage and break down, but it could be the flyback was just at its end of life. I picked that schematic because I could not find the actual one for your tv so I found a Mitsubishi tv that had a similar circuit.
The Hitachi chassis is totally different

[stj]

Re: Help substituting avalanche diode

not hard to find.
it's D907

[redwire]

Re: Help substituting avalanche diode

I would use P5KE120A TVS diode as a replacement.

[sam_sam_sam]

Re: Help substituting avalanche diode

Is there anything special about this type diode

[redwire]

Re: Help substituting avalanche diode

It's got a misleading name "avalanche diode" and nominal 120V (130-155V) rating. So it's a zener (=avalanche mode) but the wide range of reverse voltage spec. and high surge capability 2A 100usec mean it's really a TVS diode.

In the TV circuit, I can't find the schematic again but it seems to be an overvoltage clamp for when the power supply puts out too much voltage.
If the STR fails or something else happens the rail can go too high and the TVS diode clams to protect something but it will cook and short if that stays true for a long time. I see main power like 115VDC go up too high due to a bad regulator and it damages other parts, flyback too if the x-ray protection does not trip.