Marantz Tone Amp Question (PCB400)

hirscwi

AK Subscriber
Subscriber
I have a question on the Tone amp board used in many early 22xx receivers and integrated amps. Usually it's PCB400 but can have a couple other numbering schemes. I have seen the same board used in 1060, 2230, 2245, and 2270 and I bet it used in others (2225?).

My question relates to the transistors.

H403, 404, 407 & 408 are shown as PNP transistors on the schematic, and I know that KSA992 (a PNP transistor) works as a replacement. But the original transistor is 2SC493. I thought the "2SC" designation indicates an NPN transistor (according to the JIS specification). Can anyone clear this up for me? Thanks.
 
You are correct C=NPN
A= PNP
However, As you noted,They can not interchange and work. The 2sc493 must not really be a "C". It must be a misprint. It is a 2SA493. The schematic shows the transistor as pointing in(PNP)
A big :thmbsp: For catching that.
 
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At least Marantz is consistent - It is labeled "2SC493" on the schematic for 1060, 2230, 2245, and 2270...
 
I have a schematic from digital docs that is correct. It is in the 2270 Service Manual that i found this info. I can see were that could screw a guy up. You got her now!
 
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KutzlerTrans, I've check three versions of the 2270 schematics that I have and all show "SC" Any chance i could get a copy of the 2270 manual that is correct?

I will try to ad this to the service manual error thread.
 
You can download the correct 2270 SM from HiFi Engine it has the correct 2SA493's on the preamp board. IMHO everyone should have an Atlas DCA55 will save you many times.:D
 
Check the cap voltages on the boards. If 35volts, replace them with not less that 50volt caps. When the 22xx series came out they were assembled with 35 volt caps that were in spec for the earlier 2x series but too low a voltage for the later series. A major snafu and the root cause of the problems the 22xx series receivers and amps experienced.
 
Please go to Digital Docs on AK and choose the 2270 (us) On Page 30 of the service manual, Top Left, 407-408 Is listed as a 2SA493. The Schematic is also correct on that version. I second the motion about the dcapeak tester.:thmbsp: John

Man that Old Geezer sure has a lot of posts under his belt!:D
 
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I have all the versions on hifi engine and a real live printed copy. Every one of the schematics is wrong - all marked "SC". The parts list is correct - i.e. "SA". I can't find one in the Digital Docs forum (user error on my part, no doubt).

I agree that the DCA55 is useful (I've had one for quite a while) - and the Sencore Cricket works will also, just a bit more user involvement required.
 
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