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Old 15th January 2011, 02:35 PM   #1
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Default Sub for 2N3391 ??

anyone have a suggestion for replacing a 2N3391 transistor with something else? I have been through all my TO-92 devices and none seem to be a good match by looking at the spec sheets.

VCEO Collector-Emitter Voltage 25 V
VCBO Collector-Base Voltage 25 V
VEBO Emitter-Base Voltage 5.0 V
IC Collector Current - Continuous 500 mA
PD Total Device Dissipation 625 mW

V(BR)CEO Collector-Emitter Breakdown
Voltage*
IC = 10 mA, IB = 0 25 V
V(BR)CBO Collector-Base Breakdown Voltage IC = 10 mA, IE = 0 25 V
V(BR)EBO Emitter-Base Breakdown Voltage IE = 10 mA, IC = 0 5.0 V
ICBO Collector-Cutoff Current VCB = 18 V, IE = 0 100 nA
IEBO Emitter-Cutoff Current VEB = 5.0 V, IC = 0 100 nA

hFE DC Current Gain VCE = 4.5 V, IC = 2.0 mA
2N3391/A - Min:250 - Max:500
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Old 16th January 2011, 06:45 AM   #2
singa is offline singa  Singapore
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Hi, You should state the polarity,we are not walking encyclopedias.
Here are some for you to consider: European-BC337-40 npn
BC327-40 pnp

American Zetex ZTX 1049A npn
ZTX 1051A npn
ZTX 690B npn

ZTX 1149A pnp
ZTX 790A pnp
PS all TO92 devices Regards.
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Old 16th January 2011, 07:59 AM   #3
singa is offline singa  Singapore
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PS transistors suggested may not be pin compatiblewith 2N3391 so may need modification or reorientation. Regards.
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Old 19th January 2011, 09:00 AM   #4
Enzo is offline Enzo  United States
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Or tell us what they are going into. For example from the master cross reference at Peavey. they replace those with MPS8097, 2N6520, MPSA18. If you are indeed replacing old PV transistor preamp parts, then just about any suitably spec'd part will work fine. Low noise? Even better.
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Old 21st January 2011, 01:38 AM   #5
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NTE-199

http://www.nteinc.com/specs/100to199/pdf/nte199.pdf
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Old 21st January 2011, 03:17 AM   #6
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Yes Enzo you guessed it. a 1973 Peavey musician guitar amp. I tried some BC556 and MPSA06 that i had on hand but they did not work well, drew current and got hot. and yes i triple checked that i put them in the right places and that the orientation was correct.

I am working on the reverb tank drive amp. see attached schematic. I need to rebuild/rework this section with available transistors.

I also have 2N4401/4403 devices on hand if those would work?
Attached Files
File Type: pdf Reverb.pdf (67.7 KB, 22 views)
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Old 21st January 2011, 06:22 AM   #7
Enzo is offline Enzo  United States
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Sure, the 4401/4403 ought to work for the push pull. I'd also replace that 2uf/35v cap as well. That cap might be why transistors didn;t work.

No MPS8097 on the shelf?
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Old 21st January 2011, 02:09 PM   #8
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I don't think i have any MPS8097's. But i need to order some parts today. I will see what i can find
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Old 21st January 2011, 03:27 PM   #9
wg_ski is offline wg_ski  United States
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Quote:
Originally Posted by Zero Cool View Post
Yes Enzo you guessed it. a 1973 Peavey musician guitar amp. I tried some BC556 and MPSA06 that i had on hand but they did not work well, drew current and got hot. and yes i triple checked that i put them in the right places and that the orientation was correct.

I am working on the reverb tank drive amp. see attached schematic. I need to rebuild/rework this section with available transistors.
If you sub transistors and they get hot, the class AB bias is too high. More than likely, the Vbe's don't match the original. Put a trim resistor across the two diodes and adjust until the current is more reasonable.
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Old 21st January 2011, 05:11 PM   #10
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Thank you WG...I was thinking that might be the case. or that the 15K resistor for the class A 1st transistor was off. I will play with it a bit.
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