Cyrus 1 Output Transistors

[Carlosraj]

Hi,

I am looking for the best replacement transistors for my blown out PT7 transistors. I am sure a lot of you guys who have been very long in this field will be able to assist me.

Thanks

Carlos

 

[JonSnell Electronic]

They are re badged BUV28. RS stocks them; Bipolar Transistors | RS Components

 

[Carlosraj]

They are re badged BUV28. RS stocks them; Bipolar Transistors | RS Components

Thanks, Jonsnell,

Carlos

 

[Carlosraj]

Thanks, Jonsnell,

Carlos

Sorry, I forgot to ask you one more thing. Mine is Cyrus One Issue 06 using ZTX753 and ZTX 653. Refering to the service manual, these transistors have now been changed to MJE253 and MJE243. Will it be OK, if I use these MJE transistors because both the ZTX transistors have also blown.

Thanks

Carlos

 

[Carlosraj]

They are re badged BUV28. RS stocks them; Bipolar Transistors | RS Components

JonSnell, I just checked with RS. Now they are discontinued. The cyrus 2 uses BUV48, they are bigger. Can they be used to replace the P7 because seems to me that there is no other alternative. Please advise.

Thanks

Carlos

 

[ohdsp]

I've used some *13009* devices before (STW13009 I think) in my cyrus one.

RS has some from Fairchild (FJP13009TU) which are in a TO220 package:

FJP13009TU | Fairchild FJP13009TU NPN High Voltage Bipolar Transistor, 12 A, 400 V, 3-Pin TO-220 | Fairchild Semiconductor


Cheap as well, but I think the hfe may be lower than the BUV28, not 100% on that but I've had no issues.

 

[ColinA]

Little Diode seem to have BUV 48.
https://www.littlediode.com/compone...luding]=all&substring=BUV48&search_redirect=Y

 

[Ian Finch]

Little Diode also seem to charge the highest unit prices I've seen anywhere.

Never mind the price though, BUV48 is a TO3P package and BUV28 is the much smaller TO220. The pin centres, height, width, and mounting hole centre are all substantially different. There are alternatives so don't butcher your Cyrus if you think it's necessary to fit an oversize substitute.

I agree that the Fairchild FJP13009 fast switching type suggested by ohdsp is going to fit and work at least. Low gain may not be such a problem in a Quasi triple design like the Cyrus where there is plenty of driver current capability using recommended MJE243/253 drivers and this is not a high current design (3A limited by fuses) anyway.

 

[Carlosraj]

Little Diode also seem to charge the highest unit prices I've seen anywhere.

Never mind the price though, BUV48 is a TO3P package and BUV28 is the much smaller TO220. The pin centres, height, width, and mounting hole centre are all substantially different. There are alternatives so don't butcher your Cyrus if you think it's necessary to fit an oversize substitute.

I agree that the Fairchild FJP13009 fast switching type suggested by ohdsp is going to fit and work at least. Low gain may not be such a problem in a Quasi triple design like the Cyrus where there is plenty of driver current capability using recommended MJE243/253 drivers and this is not a high current design (3A limited by fuses) anyway.

Thanks, Ian. Your suggestion is to try this FJP13009s with MJE253/243. These MJEs are bigger than the current ZTX753/653 . Your advice, can these ZTXs work with the FJPs. Please advice

Carlos

 

[JonSnell Electronic]

JonSnell, I just checked with RS. Now they are discontinued. The cyrus 2 uses BUV48, they are bigger. Can they be used to replace the P7 because seems to me that there is no other alternative. Please advise.

Thanks

Carlos

What a pain, they select components for different versions. I will have a look to see which ones we use. DON'T use the wrong physical size!

 

[Carlosraj]

What a pain, they select components for different versions. I will have a look to see which ones we use. DON'T use the wrong physical size!

OK, Thanks


Carlos

 

[ohdsp]

Just for reference both CPC and RS have stock of the ZTX drivers, they are 100V 2A parts which should be capable of driving the 13009 output devices.