Help 2SC2530 / 2SA1080 Fujitsu Ring Emitter Transistor replacement

[Conehead]

G'day all,
I'm facing a dilemma repairing my Audiolabor Preamp!
One of the RET's went up in smoke but the type appears obsolete!
Its a Fujitsu 2SC2530 that I would require to get the thing back working.
THe transistor seems to be sitting in the line regulation for the power rails...
Any Ideas??

[stocktrader200]

from what I can see , 2SC2530 is a 40v NPN 0.5A transistor
If it is not in the audio path, but voltage regulation throw in a TIP31 or MJE182 and you should be fine.

[Mooly]

A circuit would be useful.
If it's a series pass device, did it fail or was it pushed ? If it's allowed excess voltage onto the rails has it caused other damage ?

[sakis]

yeap ...a schematic will help better ...if its a voltage regulator obviously you have million ways arround it if its a current source it might not be so easy ....

while you are looking for a schematic i will drop a few phone calls to the local supply shops ...you never know what i may come up with

[jacco vermeulen]

http://www.audiolabor.de/images/stor...mp-service.pdf

[tiefbassuebertr]

2SC2530 datasheet and Application Note, Data Sheet, Circuit, PDF, Pinout | Datasheet Archive
2SA1080 Datasheet pdf - SILICON PNP RING EMITTER TRANSISTOR(RET) - Fujitsu Microelectronics

Toshiba's 2SC2238 / 2SA968 must actually be a good replacement, also Onsemi's MJE15028/MJE15029 or MJE15030/MJE15031

Check out also this threads:
High Voltage BjT's for Pre-driver stages of High Power Amplifier - Overview
MJE 340 / MJE 350 (MJE340/MJE350) and BD159 - GBP (Transit frequency fT) unknown?
bipolar (bjt) transistor families for audio power output stages

[Conehead]

This site impresses me again. What a speedy reply, more than you ever could expect from a professional Customer service! Thanks for helping out and thanks to Jacco for finding those Schematics, great Job Event though they are from a different Model Audiolabor "brilliant" (I have got the "Rein") the Regulator circuit design seems to be the same. The schematics for the "Rein" on Audiolabors website are hand sketched and incomplete, missing those regulation circuits ( a shunt type in my opinion ). I have cropped the section out of the .pdf and attached here! My Preamp uses different values on the resistors and a different OpAmp (TL071 instead the drawn) Also input V in my case is 15VDC/ Output 12.5VDC. Hope this shines some more Light on it...

[Conehead]

To Mooly:
Can't say precisely what caused the damage! Both a short on the output or excess Rail voltage may have caused the transistor to fail. Either way, no fault in the input/ output does exist at this stage. A while ago the power supply (external) fell of the shelf and caused a loud 50hz hum. I repaired it, new rectifier and caps and the amp would work for a while until now! The "Rein" never had a great external Power supply, something on my "to do" list to build an improved one...

[sawreyrw]

This is a terrible circuit. You basically have 4 voltage sources in series; the 2 regulators plus the 2 amplifiers. If the sum of the voltages is not 0, the current will be huge. It will be limited by the one of the regulators, but could destroy the transistors.

[Conehead]

Nothing I can change about sawrey. This is how it has been designed by the manufacturer! The circuit has lasted some 24 years or so until today