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Old 10th Jan 2009, 8:39 pm   #1
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Question 3DD101B Transistor-Info. needed!

Help! The above is a TO-3 case silicon transistor, three of which are fitted to an amplifier in a cine-projector. One of these devices is s/c from Collector to emitter, and I can neither find a source from which to buy one, or any data on this transistor. The amp. has a 38-0-38v supply, so presumably a 2N3055 could be substituted, but if anyone can supply any info it will be welcome. Googling produces nothing relevant about this or any of the other 3Dxxx semiconductors fitted in this ?French-made? amplifier
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Old 10th Jan 2009, 10:17 pm   #2
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Default Re: 3DD101B Transistor-Info. needed!

Hi, what is the make and model of the projector; B&H, EIKI?
I have several manuals and may be able to find an equivalent; however if it's NPN then a 2N3055 should work OK.
Mike.
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Old 10th Jan 2009, 11:22 pm   #3
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Default Re: 3DD101B Transistor-Info. needed!

Hi, Mike. It's a Comet (or Comete)600. I would guess it's around 30 years old, since the amp. is made from totally discrete components. All the transistors are from this 3Dxxx series.
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Old 11th Jan 2009, 8:55 am   #4
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Default Re: 3DD101B Transistor-Info. needed!

Sorry I don't have any manuals for those, but as long as you get the right configuration (NPN or PNP) virtually any of the power transistors (as long as they will cope with the voltage and current) will do. It's likely to be only 5 or 10 watts out anyway.
Mike.
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Old 11th Jan 2009, 9:18 am   #5
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Default Re: 3DD101B Transistor-Info. needed!

Thanks for trying, Mike. I guess like me, you sometimes wonde why there are so many different semiconductors and identitfying systems. Most of us are used to Pro-Electron, JEDEC & the U.S. System, but why all these others.
Having checked a little further, I reckon a 2N3055 will do for this job,since, as you say, the amp is only about 5 or 10 watts o/p.
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Old 11th Jan 2009, 11:12 am   #6
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Default Re: 3DD101B Transistor-Info. needed!

They'll be tons to spare with a 3055.

I would check for faults such as speaker wiring and the speaker itself in case something caused the failure other than old age. And also check the driver transistors as well as they can burn out if DC coupled to the output transistors.

Let us know how you get on.

Is it a 16mm projector or a Super8 sound one?

Mike.
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Old 11th Jan 2009, 11:57 am   #7
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Default Re: 3DD101B Transistor-Info. needed!

I'll post some more info when I have delved further into this job, which is on the bench in my workshop 3/4 mile from here right now. The circuit is DC coupled-at first I thought it was a conventional class B or AB amplifier like so many more, except that Three of these 3DD 101Bs fitted on the heatsink, plus a 3DD4C(SO55size device)and about 7 small transistors on the PCB. Maybe I'll trace out the circuit(time & inclination permitting!)
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Old 17th Jan 2009, 11:10 am   #8
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Default Re: 3DD101B Transistor-Info. needed!

A brief follow up to my original post. I have now further investigated this amp., replaced the two 3DD101Bs(both s/c collector to emitter by the way) with 2N3055s, and a couple of electrolytics. After a few brief tests the amp seems to be functioning OK, having also replaced the fuses in series with the +ve & -ve supply lines-at the moment with 3.15A QB types-the o/p power is in excess of 15wpc* into 8 ohms with <10mV i/p @ 1kHz sinewave
(*My O/P meters only measure up to 10w!- I must put an AC Voltmeter accross the speaker and test the amp to full power. An attenuator resistor is fitted between the O/P point and the connection to the internal speaker, which is a 7 x 5" 4 or 5w 8 ohm type, and I am assuming the full O/P is meant for an 8 ohm load. It could, of course, be to almost any Z with a number of speakers wired in series/parrallel arrangements.
Incidentally the amp. and 9.5mm film projector were made by
Cine-technique, 45 Boulevard Beaumarchais, 75003 Paris, about whom I can find no info on the 'net
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Old 18th Jan 2009, 11:50 am   #9
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Default Re: 3DD101B Transistor-Info. needed!

Glad you got it sorted in the end.

I have had several 9.5mm projectors but not heard of that make before, but there were several companies who jumped on the bandwagon when 9.5 became popular, but some did not survive long.

Incidentally 9.5mm sound projectors are very rare and highly sought after; usually fetch well over £100 on ebay. Seen some go for as much as £200.

I have a Pathe H (240VAC version) at the moment and that works well.
Paillard Bolex are another good one; the engineering on those is superb and would easily outlast most of us.

Mike.

Last edited by Mike-repairman; 18th Jan 2009 at 12:04 pm.
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Old 18th Jan 2009, 2:19 pm   #10
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Default Re: 3DD101B Transistor-Info. needed!

Mike, subject to longer term testing, the amp. is working well. The projector it belongs to is in superb condition, c/w it's original wooden carrying case. It belongs to a film & projector enthusiast, for whom I'm repairing this, and another, older French made valve amplifier, also used with a projector
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Old 19th Jan 2009, 1:35 pm   #11
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Default Re: 3DD101B Transistor-Info. needed!

Although 9.5mm sound films are rare (compared to silent ones) it's very hard to find a projector to play them on, so he's very lucky to own it.

Mike.
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