CheeseofBorg
User Serviceable Parts
I need a replacement for a 2SC1318Q transistor, in the service manual it lists the part as 2aSC1318Q,S. Does this mean I can substitute in the S rated version?
"Quick" Transistor substitution question...
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That particular transistor is a known noisy or prone to failure. In some places it can be replaced by a KSC2383Y or KSC2690AY, but you'd have to take into account its application in your circuit and the operating parameters. More like this in Top Ten Worst Transistors - noisy, failure-prone, whatever... and replacements thread.
CheeseofBorg
User Serviceable Parts
How do I determine which one is right for this application?
Depends on what it's being used for in the circuit.
Well, you can look at the schematic and figure out the voltage and current used by and going through the transistor. Also important would be what the transistor is doing: voltage amplification, voltage regulation, current regulation, etc.
If all that is beyond what you know today (like most of it is for me), you could either 1) post a schematic for us to review and figure that out for you or 2) tell us the make and model of the piece of gear and where the transistor came from inside it and we'll find the schematic and figure it out for you. That's one of the great values of AK.
CheeseofBorg
User Serviceable Parts
This is the over all schematic, and below is the oscillator unit with the two transistors. Any suggestions on which ones to use?
CheeseofBorg
User Serviceable Parts
I can get the original, but dlucy suggested one of two replacement transistors, and suggested I post the schematic to help figure out which one is needed.
From that schematic, it appears pin 4 on the power supply delivers the power to the oscillator circuit where the two transistors are located. I can't clearly see what the voltage callout is on pin 3 (which is also connected to pin 4), but it looks like "273" or such, which is too high for the power supply and for that transistor, so I'm betting it reads something like "27.3v" or thereabouts. So, the transistors are seeing no more than 27V. They are splitting and feeding one side of the transformer that is powering the erase heads. So, these transistors aren't doing any signal or audio work, they are just managing power.
EchoWars called out the basic characteristics of the 2SC1318:
Vceo
So, you're looking for a transistor that will safely and easily handle 27V (and you know the 2SC1318 does this easily since it has a Vceo of 50V, well above the 27V it will see in this circuit).
Ic
And you're looking for a transistor that will handle at least 500 mA. You could work the math in the resistors and voltage in the circuit, but you know the upper limit is the Ic of the 2SC1318 transistor originally-specified, so any transistor whose max collector current (Ic ) is at least 500 mA is a candidate.
Pc
Again, you could do the math to calculate that amount of current and voltage to figure out how much power/heat the transistor must be able to handle, but, again, you know the upper limit is the Pc of the 2SC1318 or 625 mW. So, the replacement needs to be able to handle that or more.
ft
The ft frequency transition point of the transistor tells you the frequency at which the transistor's gain drops to just 1. The upshot of this, if I understand it correctly, is "this transistor works (amplifies well) when the frequencies it has to amplify are ft or lower." So, if you had a transistor with really low ft and you were trying to amplify UHF signals above that ft, then the transistor wouldn't work well. In your case, you aren't amplifying specific frequencies of anything, you're just controlling power, so you don't really care about the ft of this transistor or the replacement you choose.
B
The beta (B) is how much gain or amplification it has and is most-commonly called hfe in modern datasheets and, in general, you want to choose a transistor with the same (or better) amplification as the original. Your schematic said "Q or S are OK" and the original 2SC1318 versions (from the datasheet) were Q, R and S. The Q versions meant each transistor had a hfe of between 85 and 170, the R versions were anywhere from 120 to 240, and the S versions were between 170 and 340. So, if the Q or S version is OK with your schematic, you are looking for a hfe between 85 and 340.
package
You also want, if possible, to find a transistor with the same or similar package. The 2SC1318 is a TO-92. So, when you look for a replacement, a starting point would be all those transistors who meet the above operating characteristics and limits and which are available in the TO-92 package. That's a lot.
pinout
The three legs of a transistor will come out of the package in a certain order. ECB (emitter, collector, and base) and BCE (base, collector, and emitter) are common. When you choose a replacement transistor, the best choice is typically one that meets or exceeds the operating characteristics and limits and is in the same or similar package and has the same pinout order. This is mainly so you don't install and solder the transistor in an incorrect order and damage something in your device. However, it is simple to change the order of the replacement transistor as it goes into the holes in the PCB to get the order right for your circuit, so this is not a hard limit. it is more of a practical, reduce-your-errors kind of guideline.
The 2SC1318 transistor has a ECB pinout order or you could say emitter pin 1, collector pin 2, and base pin 3. If possible, our chosen replacement will be the same.
Replacement Candidates
The Top Ten Worst Transistors - noisy, failure-prone, whatever... and replacements thread is mostly about replacing transistors that carry audio signals, but those transistors have already been vetted for transistors with similar or better operating characteristics and limits and for general available and low cost. So, that list is a fine place to start since we know the 2SC1318 is on it.
That list says the recommended replacements for many vintage stereos where that transistor is used are the KSC2383Y and the KSC2690AY. You can look these two up, dropping the trailing letters, at any online parts place. I like Mouser.com and digikey.com because they have such good data and sorting on the parameters you're looking for, but many other places are good, too.
At Mouser, I can see the KSC2383
There are certainly more replacements available and you could use the above approach to find more to choose from. If you want to be safe, wait for one or more more-experienced AK'ers to chime in and point out the flaws in my approach. That'll be educational for both of us and might save you shipping charges on the second order of replacement parts.
EchoWars called out the basic characteristics of the 2SC1318:
Vceo (the maximum voltage the transistor's valve can handle) is 50V
Ic (the maximum current the transistor can flow) is 500mA
Pc (the maximum power dissipation the transistor can handle) is 625mW
B (the Beta or amplification power) is 150
ft (the frquency at which the transistor transitions from amp to not-an-amp) is 200MHz
Ic (the maximum current the transistor can flow) is 500mA
Pc (the maximum power dissipation the transistor can handle) is 625mW
B (the Beta or amplification power) is 150
ft (the frquency at which the transistor transitions from amp to not-an-amp) is 200MHz
Vceo
So, you're looking for a transistor that will safely and easily handle 27V (and you know the 2SC1318 does this easily since it has a Vceo of 50V, well above the 27V it will see in this circuit).
Ic
And you're looking for a transistor that will handle at least 500 mA. You could work the math in the resistors and voltage in the circuit, but you know the upper limit is the Ic of the 2SC1318 transistor originally-specified, so any transistor whose max collector current (Ic ) is at least 500 mA is a candidate.
Pc
Again, you could do the math to calculate that amount of current and voltage to figure out how much power/heat the transistor must be able to handle, but, again, you know the upper limit is the Pc of the 2SC1318 or 625 mW. So, the replacement needs to be able to handle that or more.
ft
The ft frequency transition point of the transistor tells you the frequency at which the transistor's gain drops to just 1. The upshot of this, if I understand it correctly, is "this transistor works (amplifies well) when the frequencies it has to amplify are ft or lower." So, if you had a transistor with really low ft and you were trying to amplify UHF signals above that ft, then the transistor wouldn't work well. In your case, you aren't amplifying specific frequencies of anything, you're just controlling power, so you don't really care about the ft of this transistor or the replacement you choose.
B
The beta (B) is how much gain or amplification it has and is most-commonly called hfe in modern datasheets and, in general, you want to choose a transistor with the same (or better) amplification as the original. Your schematic said "Q or S are OK" and the original 2SC1318 versions (from the datasheet) were Q, R and S. The Q versions meant each transistor had a hfe of between 85 and 170, the R versions were anywhere from 120 to 240, and the S versions were between 170 and 340. So, if the Q or S version is OK with your schematic, you are looking for a hfe between 85 and 340.
package
You also want, if possible, to find a transistor with the same or similar package. The 2SC1318 is a TO-92. So, when you look for a replacement, a starting point would be all those transistors who meet the above operating characteristics and limits and which are available in the TO-92 package. That's a lot.
pinout
The three legs of a transistor will come out of the package in a certain order. ECB (emitter, collector, and base) and BCE (base, collector, and emitter) are common. When you choose a replacement transistor, the best choice is typically one that meets or exceeds the operating characteristics and limits and is in the same or similar package and has the same pinout order. This is mainly so you don't install and solder the transistor in an incorrect order and damage something in your device. However, it is simple to change the order of the replacement transistor as it goes into the holes in the PCB to get the order right for your circuit, so this is not a hard limit. it is more of a practical, reduce-your-errors kind of guideline.
The 2SC1318 transistor has a ECB pinout order or you could say emitter pin 1, collector pin 2, and base pin 3. If possible, our chosen replacement will be the same.
Replacement Candidates
The Top Ten Worst Transistors - noisy, failure-prone, whatever... and replacements thread is mostly about replacing transistors that carry audio signals, but those transistors have already been vetted for transistors with similar or better operating characteristics and limits and for general available and low cost. So, that list is a fine place to start since we know the 2SC1318 is on it.
That list says the recommended replacements for many vintage stereos where that transistor is used are the KSC2383Y and the KSC2690AY. You can look these two up, dropping the trailing letters, at any online parts place. I like Mouser.com and digikey.com because they have such good data and sorting on the parameters you're looking for, but many other places are good, too.
At Mouser, I can see the KSC2383
has a Collector- Emitter Voltage VCEO Max of 160 V which is way more than we need (27V circuit or 50V Vceo of the 2SC1318) and that's good
has a Continuous Collector Current (max) of 1 A which is easily twice as strong as had (0.5 A in the 2SC1318) and that's great
has a Pd - Power Dissipation of 0.9 W which is more than we need (625 mW in the 2SC1318)
if we were handling audio signal we'd care about ft (and the KSC2383 can handle up to 100MHz which means it would do fine in audio circuits) but we don't care in this power-only application
and the datasheet PDF tells us
Mouser also tells me about the KSC2690has a Continuous Collector Current (max) of 1 A which is easily twice as strong as had (0.5 A in the 2SC1318) and that's great
has a Pd - Power Dissipation of 0.9 W which is more than we need (625 mW in the 2SC1318)
if we were handling audio signal we'd care about ft (and the KSC2383 can handle up to 100MHz which means it would do fine in audio circuits) but we don't care in this power-only application
and the datasheet PDF tells us
there are several versions of this transistor which each give us different ranges of hfe:
The pinout is ECB which is the same as our 2SC1318
All that means the R, O or Y version of the KSC2383 would work well in our circuit, it would fit fine, and the KSC2383YTA are $0.41 each and they've got 2,418 in stock and ready to ship. The Y at the end of the KSC2383 is the hfe rating and the TA part are more letters they jam on there to describe the type of packaging the devices are shipped and stored in (e.g. bulk, tape, reel, etc.). For our hobbyist, one-at-a-time purposes, those trailing letters don't have any real meaning and can be ignored for all purposes other than finding the lowest cost on the online sites. You might find the TA version is $0.10 cheaper than the non-TA version because it costs them less to pick in the warehouse from an automated tape dispenser than from a bulk bin where a human has to pick up and count the devices.R 60 to 120
O 100 to 200
Y 160 to 320
The package is TO-92, the same as our original transistorO 100 to 200
Y 160 to 320
The pinout is ECB which is the same as our 2SC1318
has a Collector- Emitter Voltage VCEO Max of 160 V which is way more than we need (27V circuit or 50V Vceo of the 2SC1318) and that's good
has a Continuous Collector Current (max) of 1.2 A which is easily twice as strong as had (0.5 A in the 2SC1318) and that's great
has a Pd - Power Dissipation of 1200 mW which is more than we need (625 mW in the 2SC1318)
if we were handling audio signal we'd care about ft (and the KSC2690 can handle up to 155MHz) but we don't care in this power-only application
and the datasheet PDF tells us
So, there you have two replacement recommendations (from a complete amateur) and the reasoning I used to find them. Both of these will work, will fit, are very easy to find, they are in stock, and they are very cheap.has a Continuous Collector Current (max) of 1.2 A which is easily twice as strong as had (0.5 A in the 2SC1318) and that's great
has a Pd - Power Dissipation of 1200 mW which is more than we need (625 mW in the 2SC1318)
if we were handling audio signal we'd care about ft (and the KSC2690 can handle up to 155MHz) but we don't care in this power-only application
and the datasheet PDF tells us
there are several versions of this transistor which each give us different ranges of hfe:
The pinout is ECB which is the same as our 2SC1318
All that means the R, O or Y version of the KSC2690 would work well in our circuit, it would be an OK upgrade if you needed it, it would take a little work to make it fit, and the KSC2690AYS are $0.50 each and there are 6,318 in stock and ready to ship.R 60 to 120
O 100 to 200
Y 160 to 320
The package is TO-126 which is not the same as our original transistor. This is a physically larger package, which accounts for its ability to dissipate more heat. The TO-126 will probably still fit in all but the tightest-packed boards, but it'll need more shoulder room. The pins are so slightly larger, so you might have to use a pin vise or very, very small drill to make you PCB holes slightly larger. This would be a great upgrade if you were concerned about the power handling or heat generation of the existing transistor. This TO-126 based device can handle more power/current/heat.O 100 to 200
Y 160 to 320
The pinout is ECB which is the same as our 2SC1318
There are certainly more replacements available and you could use the above approach to find more to choose from. If you want to be safe, wait for one or more more-experienced AK'ers to chime in and point out the flaws in my approach. That'll be educational for both of us and might save you shipping charges on the second order of replacement parts.
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Agreed.
I guess that helps to highlight a mistake I made right off the bat. I should have asked why or in what way did the original transistor fail.
Both the recommended replacements would "beef" up the transistor in terms of voltage, current and power handling. The TO-126 based KSC2960AYS would be a beefier, stronger replacement.
CheeseofBorg
User Serviceable Parts
I might as well ask this here rather than start a new thread, the other thing I need a modern replacement for is a 2SK30D. Digikey said the closest thing they have is the 2N4338-E3-ND, but that it was not a very close replacement. Does anyone have any suggestions for that?
nj pheonix
Lunatic Member
Searches show 2 NTE #s
NTE frowned upon in these parts . I think I'd look further. The lessons from the first part should prove useful here. I'd help more but I'm learning along with you
NTE frowned upon in these parts . I think I'd look further. The lessons from the first part should prove useful here. I'd help more but I'm learning along with you
I didn't find any 2SK30D mentions here on AK and I could only find a 2SK30ATM datasheet on the Internet. It's a JFET instead of a more-common bipolar transistor (like we've been talking about), but the same approach above should work so long as you search for JFETs and their paramtere types instead of bipolar transistors.
Here are two thread you could model your search after to find what you're looking for. These also have additional resources where you might find a match:
Help me fine the correct Jfet
Replacement JFET... what's difference between transistor?
Good luck! Post back here with what you find!
gslikker
Super Member
Guess the mentioned replcement might be good.
You could try to find bf245a but it is obsosete also. My Pioneer SA900 was supposed to have 2SK30 in (actually it did have 2SK17 and one was messing up dc voltage) and I replaced with BF245a.
Observe antistatic precautions when handling the new FET as well during exchanging. Easiest way is wrap a very thin wire or solder around the legs, and take it away after soldering in the circuit card.
You could try to find bf245a but it is obsosete also. My Pioneer SA900 was supposed to have 2SK30 in (actually it did have 2SK17 and one was messing up dc voltage) and I replaced with BF245a.
Observe antistatic precautions when handling the new FET as well during exchanging. Easiest way is wrap a very thin wire or solder around the legs, and take it away after soldering in the circuit card.
What is it used in or are you doing a new design? Do you have this part to show a pic of its stamping? You are sure that the jfet is dead if you need a replacement? Have to tested the part out of circuit to verify it is not operating properly?
I also have no idea what the "D" grade is, nor who is the mfg is. We all know Toshiba made them, as they go back to the 70's. Usually the suffix means the Idss spec, which I am not sure what "D" would be as that is not a usual Toshiba suffix, they usually use, R,O,Y, GR,BL.
At one time Fairchild made a 2sk30 clone, KSK30, which was originally from Samsung, but Fairchild bought that business unit from Samsung. It has since been discontinued. It came in 4 Idss grades. I have never seen any for sale.
As pointed out by in this thread Help me fine the correct Jfet, 2sk117 is a possibility, so is the Vishay 2N4338 series, if you know what the "D" suffix means.
Jfets are usually very reliable.
Using an old (1979) Sylvania cross reference, I can find that a 2SK30D crosses to a ECG132. The parameters for that ECG132 are as follows:
When I browse through Mouser in the semiconductors - discrete - transistors - JFET section and limit my search to devices
There is one that is an exact match, 8 mA - 20 mA, so I follow that and look at the datasheet for that part 2N5486
The datasheet, to me, looks like it would be a good replacement for the above-mentioned ECG132, a compatible cross-referenced part for the 2SK30(D).
Anyone on AK who can read those two (above ECG132 characteristics and the 2N5486 datasheet) and give an expert opinion?
JFET, N-channel, VHF amp/mixer, NF 4dB Max at 400 MHz
Transconductance gfs Typ umhos 4,500
Gate to Source Cutoff Voltage
Vgs (off) MAx V = 6
Zero-Gate Voltage Drain Current Idss mA min - max = 8 - 20
Gate to Source Breakdown Voltage BVgss Min V = 25
Input Cap Ciss Max pf = 5
Transfer Cap Crss Max pf = 1.2
Device Diss Pd Max mW = 310
Transconductance gfs Typ umhos 4,500
Gate to Source Cutoff Voltage
Vgs (off) MAx V = 6
Zero-Gate Voltage Drain Current Idss mA min - max = 8 - 20
Gate to Source Breakdown Voltage BVgss Min V = 25
Input Cap Ciss Max pf = 5
Transfer Cap Crss Max pf = 1.2
Device Diss Pd Max mW = 310
When I browse through Mouser in the semiconductors - discrete - transistors - JFET section and limit my search to devices
- in-stock
- through hole
- 310 mW or great dissapation
- N-channel
- single channel
There is one that is an exact match, 8 mA - 20 mA, so I follow that and look at the datasheet for that part 2N5486
Part 2N5486 http://www.mouser.com/ProductDetail/Central-Semiconductor/2N5486
Datasheet PDF http://www.mouser.com/ds/2/68/2n5484-5486-51207.pdf
Datasheet PDF http://www.mouser.com/ds/2/68/2n5484-5486-51207.pdf
The datasheet, to me, looks like it would be a good replacement for the above-mentioned ECG132, a compatible cross-referenced part for the 2SK30(D).
Anyone on AK who can read those two (above ECG132 characteristics and the 2N5486 datasheet) and give an expert opinion?
