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Old 1st January 2006, 10:26 AM   #1
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Default old device specs


I'm restoring an old early 70's one-of-a-kind amp made by a talented friend (now deceased) and am looking for the specs for these devices.



Knowing the guy who built it, the devices are probably hand selected for CEv. Likely also selected as full SOA devices in that I*V=P where P is a constant up to the current limit. (that's how this fellow built his personal stuff) But I know not P or I. It uses 6 of the SJ3679/8 devices per channel w/ a 40V regulated supply. Runs in class A for 8 ohm load ~ 1.5A bias per side. The other devices are the drivers.

Just trying to get a better idea of what I'm working with. The amp works just fine, (better than many 'modern' amps - i.e. clean power bandwidth to over 100K, even with these old devices) and not I'm planning on replacing these devices unless it's necessary. I've been unable to find these as they are so old and my library doesn't go back that far.

This is a very advanced amp for its time.

Thanks for any info,

~ Sorabji
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Old 1st January 2006, 10:37 AM   #2
Netlist is offline Netlist  Belgium
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I have no indication of the existence of these devices.
Not by number and not by Motorola Xref.
2SC36XX is possible but these would be Sanken or for the 2SC3681, Sanyo.
Could you provide a picture?

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Old 1st January 2006, 11:21 AM   #3
Onra is offline Onra  Germany
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i looked up an older ECG-list and found ECG-replacements for three of them:
SJ3678 is NPN replaced by ECG130 (maybe a 2N3055), TO3,
SJ3679 is PNP replaced by ECG219 (complementary type of ECG130), TO3;

SJ3680 is NPN replaced by ECG175 high voltage audio in case TO66
SJ3681 not found in this list, but ECG´s complementary type to ECG175 is ECG 38 in same case and voltage range.
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Old 1st January 2006, 11:53 AM   #4
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$orabji!, if you by any chance have a schematic I'm pretty sure that the gathered expertize here can find suitable replacements.
/Per-Anders (my first name) or P-A as my friends call me
PA03 LM4780 amplifier group buy, SIGN UP HERE for the group buy 0 boards left. 118 paid.
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Old 1st January 2006, 12:44 PM   #5
Netlist is offline Netlist  Belgium
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Onra made me dig a little deeper.
So, for the SJ3678 we have:
IC: 15
PD: 115
ft: 800Khz
Hfe: 40

IC: 15
PD: 150
ft: 4Mhz min.
Hfe: 20 min.

VEB: 6
IC: 3
PD: 40
ft: 10Mhz
Hfe: 50 typ

ECG38 (no SJ3681 here as well)
IC: 2 cont. 5 peak
PD: 35
ft: 20Mhz
Hfe: 50typ

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Old 2nd January 2006, 01:19 AM   #6
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Many thanks!
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Old 2nd January 2006, 03:24 AM   #7
anatech is offline anatech  Canada
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Hi $orabji!,
Those do sound like old Motorola part numbers for "factory numbered" devices. Motorola will have no specs on these numbers. They are like a state secret.

Be very cautious of subs listed by ECG or NTE. Do not cross in and out of these manuals.

Where did you find listings for those? Just curious. These numbers remind me of older Marantz part numbers.

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Old 2nd January 2006, 08:35 AM   #8
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Data comes from an old '89 ECG catalogue.
Indeed, one can only hope the info is reliable.
http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search?OpenForm already lists different specs for some devices parameters when looking at the datasheets.

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Old 2nd January 2006, 10:53 AM   #9
djk is offline djk
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Chris is right, they look like house numbers used by Marantz.

The outputs are the 2N5631(NPN), and the 2N6031(PNP).

The drivers are the 2N3584(NPN) and 2N6421(PNP)
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