Couldn't he install small value capacitors, about .01uf
to dampen the oscillation?
On Tue, 22 Feb 2000, gurriesm wrote:
From: gurriesm <gurriesm@...>
Although these part may not be used in SAE original equipment, the
information is usefull for the high power amplifiers such as the SAE2500,
SAE2600, A1001 ect... I own a Marantz 2600 reciever which is rated at
300W/channel. I cannot say these transistors will work without any
oscillation since the Ft is very high. James has already stated to watch
out for the transistors with to high of a FT. Anyway, just passing on
the information.
By the way, I finish a complete restoration of my SAE2600 Amp. The only
problem I have is the left channel with substituted second stage
transistors after the Diff input. The amplifier oscillates when going
into hard clipping. If I recall, they are S1376 (PNP) and S1375 (NPN)
transistors. I believe these to be SAE part numbers. James, what is the
nearest direct replacement you would recomend today?
Anayway, while I was restoring my 2100L, I was checking out the voltage
regulator stage and found one pair of complementary transitor that are
the exact type that used in the 2600. I pulled them out and replaced the
descrete transistor regulator cicuit with LM7815 and LM7915 Linear
regulators IC instead. But I am only half way there since I need another
pair to finish the Job.
---------------- Begin Forwarded Message ----------------
Date: 02/22/2000 2:54 PM
Received: 02/22/2000 3:14 PM
From: manta22@...
Reply-To: Marantz Sig, MarantzTalk@...
To: Marantz Sig, MarantzTalk@...
From: manta22@...
As I mentioned before, I've found some replacement power transistors for
my
2325 output stage. They are made by Sanken (available through Allegro
distributors in the US) and the part numbers are: 2SC3263 for the NPN and
2SA1294 for the PNP. These are complementary pairs that are made for audio
power amplifiers. They are epitaxial power transistors in a plastic MT-100
(TO-3P) package and have the following characteristics:
max power= 150W
Vceo= 230V
Ic= 15A
hfe= 50 min
ft= 35MHz
In addition, these transistors have excellent beta linearity at high
collector current and they have a good safe operating area.
These are pretty high power transistors and would probably be good
replacements for a Marantz 2600, 2500, 2385, or a 2325 output stage. Lower
power amplifiers could use a lower power version of this series of
transistors.
A data sheet for the NPN & PNP can be found at :
This website is miserably slow and hard to navigate, so good luck.
Regards, Neil Albaugh
Sr. Applications Engineer
Linear Division
Burr-Brown Corp.
Tucson, AZ
To:
cc: albaugh_neil@... (bcc: Neil Albaugh/Tuc/BB1)
Subject: Re: [MarantzTalk] Hello!
In a message dated 2/12/00 8:34:04 PM US Mountain Standard Time,
tesla@... writes:
<< I need some replacement transistors, but have found little luck with
some
of them. The output transistors were NTE replacements, (I would like to
get
the original Motorola's, preferably matched), but I have had no luck
finding
some of the scope-circuit drivers. Thanks,
Gene >>
Gene;
I found some replacements for the output transistors in my 2325. They
actually have better characteristics than the original ones used by
Marantz.
They (the better ones) were not available back in the 70s. The original
power
transistors were in a metal TO-3 package, but the replacements are in a
metal-tab plastic package. Never fear-- their leads can be bent down
easily
to fit the TO-3 sockets. If anyone is interested, I'll look up the part
number for the new transistors.
Semiconductor wafer processing is now much more repeatable now than it was
20
to 25 years ago, so matching the output transistors is less important now
than it used to be. It would take a curve tracer to do the matching
properly,
so it's not something an average hobbyist is not going to be able to do.
Anyone know of a source for scope tubes that fit a Marantz 2600?
Regards, Neil Albaugh
Sr. Applications Engineer
Linear Division
Burr-Brown Corp.
Tucson, AZ
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----------------- End Forwarded Message -----------------
Best Regards,
Mark Gurries
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Battery Charging and Power Systems Application Engineer
Linear Technology,1630 McCarthy Blvd, Milpitas, CA, 95035
WRK(408) 954-8400 x3864 Email: gurriesm@...
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