Product Categories. Images are for reference. See Product Specification. More details for 2SA can be seen below. Looking for 2SA?
|Published (Last):||5 January 2006|
|PDF File Size:||13.72 Mb|
|ePub File Size:||19.72 Mb|
|Price:||Free* [*Free Regsitration Required]|
Hello, I started to refresh my Marantz unit, and it seems that I'm going to change almost everything inside. Only ceramic and film caps will remain. I already replaced the electrolytic caps and all resistors with metal film. I pulled out the old transistors and measured them. While they are not leaking at all, hfe is a bit wild between them so I'd like to replace them.
I added the schematics for the boards in question. I can get lots and match hfe on pairs. Both pairs have different gain codes so I can match almost all transistors from the amp. I'll list the transistors I found: Power Supply: H - 2scp hfe in the datasheet P is H - 2scq hfe in the datasheet Q is Buffer Board: HDHD04 - 2scT measured hfe was between - - datasheet specs hfe at HE09 - HE12 - 2sc I guess.
Transistors have C written. Power Amp: I haven't gotten to tear down the pcb but the transistor numbers are consistent with the schematic. I have no idea. I'd like to replace all since working on this unit is a real pain. I don't want to go back inside for the next 10 years, I just want to enjoy it. Right now everything is teared down from the amp so while I'm reacaping, re-resistoring I'd re-transistor as well The output transistors are 2SD, and they seem in working order.
But those I can access more easy, no need to replace them now. So, besides the larger to Attached Images PS. The small signal transistors will not be damaged sometimes even for the life, anybody's. If it ain't broken, don't fix it.
Gajanan Phadte. Originally Posted by Welcome. Many Jap amps are quite critical of the transistors used, particularly in the output stages.
Its not just gain, they actually differ slightly in absolute turn on volts maybe different manufacturing techniques and doping back then which can be a big factor where critical bias voltages are needed and generated.
For example replacing the drivers and outputs may give a low or no quiescent current that is non adjustable without altering other components in the bias network.
There can also be very real stability issues due to differing inter junction capacitance. That said, the small signal stages, while showing no benefit for swapping devices, should show no real problems either. From beginner to advanced. Ok, thank you. What bothers me is that the tone preamp transistors have a wide hfe between the same type. So I could do this in the lower stages but not in the final one? The hfe variation is a non issue thanks to the action of negative feedback.
Whether you uses an hfe of a or , the circuit would still perform essentially the same. If an hfe of is the lowest of what is in there already, then I would say that was actually pretty high even by todays standards. Honestly, you won't gain anything by replacing these. Originally Posted by Mooly. Your biggest problem is the other characteristics not hfe of the transistors in the power amp causing serious problems if you start swapping them for other modern types. You would need to rework and change some component values.
The preamp stages will work with pretty much anything. There is no real reason to suspect the transistors will fail They should be as good as the day they were made. BB code is On. Smilies are On. Forum Rules. All times are GMT. The time now is AM. Resources saved on this page: MySQL User Name. Stay logged in? Mark Forums Read.
Solid State Talk all about solid state amplification. Please consider donating to help us continue to serve you. Page 1 of Thread Tools. Attached Images. View Public Profile.
Send a private message to Trileru. Find More Posts by Trileru. Send a private message to Welcome. Find More Posts by Welcome. Send a private message to gmphadte. Find More Posts by gmphadte. Send a private message to Mooly. Find More Posts by Mooly. Quote: Originally Posted by Mooly The hfe variation is a non issue thanks to the action of negative feedback. Posting Rules. Similar Threads.
Transistor replacement. Transistor Replacement. Frequently Asked Questions Did you forget your password?
2SA684 Transistor. Datasheet pdf. Equivalent
2SA684 Datasheet PDF - Daya Electric Group Co., Ltd.
2SA684 Bipolar Transistor