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PD1515 NPN Bipolar Transistors & its Data !

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Danieljohn

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Good Evening Dear fellow forum Members !

I'm Searching for 1970's-80's Cosmic LAB-3000 Stereomaster Amplifier's PD1515 NPN Bipolar Transistors and its Datasheet also.
I Request all Senior forum members to help me find the above mentioned Transistors & its Datasheet.

Thanks in Advance !

Regards
IRONICAL IMG-20181010-WA0006.jpg
 

Danieljohn

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Yes Dear Quad,
1.I posted though only in electro-tech-online forum not in many.
2.yes I came across Stephen's PD1515 but couldn't join in electrondepot forum bcuz of language barrier.
3.Stephan's thread is almost a decade old.
4.if I couldnt get electro-tech-online Fezder's PD1515 Transistors of 2013's Thread, I thought trying with Stephen would be waste of time.
5.PD1515 was available here in 70's-80's.

Thanks Quad for your Support. :)

Regards
IRONICAL
 

Danieljohn

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Just a naive question !
Does different transistors sound differently in a same amplifier (Design/Topology etc) with same matching Speakers?
 

saikatbiswas82

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Don't know much about amplifier design but when I was doing my personal research on jlh amp during my build, many claimed in diyaudio that MJ15003 sounds better than 2N3055. Even Nelson pass modified his original design of F5 (I may be wrong - it could be F5 or one of his other designs) with low cost IRFP240 and I think he was more satisfied. (I don't have the thread link available now but I read it somewhere)
 

Danieljohn

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Dear Saikat Biswas,

We both & many who heard the difference by different transistors in a same amplifier agrees that it's a fact ! But it's hard to convince a 40 years experienced Sound Engineer who happens to be working on my Amplifier to use the original PD1515 instead of 2N3055 (which are Good if they are Original Motorola with Aluminium cover I believe ) as I'm too Sentimental about them. His point is that Transistors doesn't make any difference to sound, he says it's related to how the circuit is designed & the Topology of it. May be he might be trying to prevent the trouble I would be going through to get the original Transistors or he believes that Genuinely I don't know.
 

yugaaa

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From my own set of building amplifiers it is not easy to swap transistors with better ones and expect the amp to sound as good . Most of the time they sound bad . Reason is the speed of modern transistors are fast and the older gen transistors like 2n5055 2n3777 etc are slow devices with lesser die area . Additional compensation needs to be done in the circuit to use new gen transistors .

If the circuit is similar to philips then it must be a flavour of RCA circuits . would it be possible to post a pic of the amp internals ?
 

Danieljohn

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Dear Yugaaa,
1.I completely agree with you ! 10834776_1679531545606566_1968388207_o.jpg 10849670_1679531522273235_604380054_o.jpg
2.this Cosmic LAB-3000 Stereomaster amplifier is from 70's but I believe & I was told that it's slightly different from the other Amplifier which my Dad bought in 80's which is bit refined (PD1515) & the one got affected by adjusting Bias by ear not multi meter !

3.If only one Transistor blew & DC chewed up pretty much everything including Speaker, VU meter etc while adjusting bias. now would Amplifier rejuvenates just by replacing that failed Transistor? Or both transistors need to be changed? I was told that all interlinked components (driver transistors, presets etc) must be changed ! by a Senior Technical Engineer from mumbai not directly related to Cosmic company.
 

yugaaa

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Most probably the transistors blew because of the trimmer . Those days trimmers /presets can be tricky with dust settling on them . First get the trimmers replaced . Check for failed driver transistors . The electrolytics must also have dried by now . The sq of the amplifier is also due to the design layout of the circuit . If possible buy a couple of 3773 transistors and wire them up . The circuit wont fail , at the most you might have a bit of distrotion , but if the circuit works then fine tuning with the right output transistor will not be a problem . In fact there are a whole range of industrial slow speed transistors which are very robust and would never fail .
 

Danieljohn

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Thanks Dear Yugaaa !
For valuable Inputs. :)

Most probably the transistors blew because of the trimmer .

1.Yes ! While adjusting quiescent current/bias if that's what they are.

Those days trimmers /presets can be tricky with dust settling on them .

2.Cosmic LAB-3000 Stereomaster Amplifier cover was completely sealed type I don't this could be the reason but can't say for sure.

First get the trimmers replaced .

3. Sure !

Check for failed driver transistors .

4. Ok even if it's not failed dont you think they must have got affected by the transistor, Speaker, VU meter failure?

5.I want to replace them even if they are in good condition unless I don't find the original ones.

The electrolytics must also have dried by now .

6. within how many years electrolytics can get dried?

7.actually the left channel capacitor is damaged I believe by the looks of it.

8. Capacitors are 3000uf 60V so I would like to know to what extreme level we can go in choosing capacitors which can be accommodated within the amplifier.

The sq of the amplifier is also due to the design layout of the circuit .

9.What is sq? Sound Quality? If so yeah ! But I Love to believe it's bcuz of those Transistors as well !

If possible buy a couple of 3773 transistors and wire them up .

10. Ok but 2N3055 doesn't work? Bcuz I already bought them. Anyway I'll get 2N3773 as well kindly suggest which company ones.

The circuit wont fail ,

11.Thank God !

12.btw I didn't mention that right channel is in working Condition.

at the most you might have a bit of distrotion ,

13.What could be the reason for this?

but if the circuit works then fine tuning with the right output transistor will not be a problem.

14.That's Amazing !

15.Pls suggest all the right output transistors model numbers & their makers names as well.

In fact there are a whole range of industrial slow speed transistors which are very robust and would never fail .

16.let me know the whole range of slow speed transistors model numbers & their makers names and whats Great about a transistors being slower?

17. After understanding that PD1515 was infact been used in Laboratory Linear Power Supply Units my respect towards industrial electronic components Grew Leaps & Bounds !

Thanks once again Yugaaa for being soo Supportive. :-D IMG-20181008-WA0016.jpeg
IMG-20181008-WA0011.jpeg IMG-20181008-WA0004.jpeg IMG-20181008-WA0002.jpeg
 
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Danieljohn

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View attachment 31651
View attachment 31652 View attachment 31653 View attachment 31654 [/QUOTE]

1st Picture is of right channel capacitor which seems to be in Good condition though i'll be replacing them with biggest possible safest good capacitors.

2nd Picture is of a failed/DC Affected capacitor.

3rd Picture is of 100K green mylar capacitor absence or the domino effect which actually caused the failure of left channel this was told to me as a reason but I'm not sure.

4th Pictures shows the slight difference in design from the 70's version of Cosmic LAB-3000 Stereomaster Amplifier.
 

yugaaa

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The PD1515 seems to be made by ferranti . Ferranti used to have only F instead of ferranti written and I am thinking cosmic might have imported them from the UK .
 

yugaaa

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2.Cosmic LAB-3000 Stereomaster Amplifier cover was completely sealed type I don't this could be the reason but can't say for sure.

Might be sealed , but humidity temperature can wear down the parts . The trimmers are good for adjusting a few times . After that the carbon wears out . Best way is to spray a bit of wd40 and coconut oil to keep it working . I do not know if contact cleaner sprays are avaliable these days .

4. Ok even if it's not failed dont you think they must have got affected by the transistor, Speaker, VU meter failure?

If they are working then it is fine . Getting equivalent parts might be cumbersome .

6. within how many years electrolytics can get dried?

Depends on the quality . If the product is in constant use it might last a while , but if the product is not used for a long time then the electrolytics will fail . The electrolyte reacts inside and corrodes the cap if it is not charged .

7.actually the left channel capacitor is damaged I believe by the looks of it.

Change all . Too vintage to be functioning .

8. Capacitors are 3000uf 60V so I would like to know to what extreme level we can go in choosing capacitors which can be accommodated within the amplifier.

Trying to get a similar size one is the most important thing . value can even go upto 4700 uf/63v

9.What is sq? Sound Quality? If so yeah ! But I Love to believe it's bcuz of those Transistors as well !

Yes sound quality . Not just the transistors but the circuit and implementation as a whole . These days PCB designs are right angles and squares .

10. Ok but 2N3055 doesn't work? Bcuz I already bought them. Anyway I'll get 2N3773 as well kindly suggest which company ones.
ok . I got confused with the bux39 . Seems like the 1515 is a darlington . Only 3 options are there . 1 . TIP 142 , 2. MJ11022 3.2SD2488 . The TIP is locally avaliable , but need to check the voltage output of the power supply . 2SD2488 seems to be the closest in terms of PD1515 in the gain dept .

12.btw I didn't mention that right channel is in working Condition.
Is it possible to measure voltages ? I also see fuses blown . I am assuming the fuses blew on the left channel ?

16.let me know the whole range of slow speed transistors model numbers & their makers names and whats Great about a transistors being slower?
Nothing is great . Implementation is where it matters . In fact a fast switching device is the preffered one these days .

17. After understanding that PD1515 was infact been used in Laboratory Linear Power Supply Units my respect towards industrial electronic components Grew Leaps & Bounds !
 
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reubensm

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Dear Saikat Biswas,

We both & many who heard the difference by different transistors in a same amplifier agrees that it's a fact ! But it's hard to convince a 40 years experienced Sound Engineer who happens to be working on my Amplifier to use the original PD1515 instead of 2N3055 (which are Good if they are Original Motorola with Aluminium cover I believe ) as I'm too Sentimental about them. His point is that Transistors doesn't make any difference to sound, he says it's related to how the circuit is designed & the Topology of it. May be he might be trying to prevent the trouble I would be going through to get the original Transistors or he believes that Genuinely I don't know.

A note from my experience. I have finished restoring a badly tampered with NAD 3020 which had loads of Jugaad repairs done on it. One of the 2N3055 output transistors, the one on the left channel, had been replaced with a Chinese one. This channel was sounding dull and there was clear channel imbalance as a result I had a Motorola 3055 transistor which i had kept in my collection as a replacement for my 3020 and was able to replace this Chinese 3055. The moment this replacement happened, the concerned channel returned to normal the channel imbalance disappeared. So in this case, using an original Motorola replacement did the trick.

Alternatively, the driver transistors on the power stage of this amplifier had also been replaced by local ones. The NAD 3020 classic design uses the 2N6551 - 2N6554 pair. These are classic transistors and not easy to get in the spares market. I was in touch with a vendor in the United States who was asking for $50 including shipping for 2 pairs. Hence I decided to look at alternates. I first tried 2 pairs of BD139 - BD140 with good results. While the gain and presentation sounded great, I was not completely satisfied with the outcome as that "zing" factor, which the 3020 is famous for, seemed to be missing. I did some research by trying different transistor combinations and final arrived at the answer, which was the MJE 2955 - MJE 3055 pair. Though the pin configuration was a bit different and hence I had to juggle around a bit, but the outcome was to my satisfaction. This is the earliest model of the NAD 3020 with a base-mounted standing Transformer and a back mounted PSU board. To my ears, its now sounds so nice that I am enjoying its burn in with 24 hours music at home, we are now at the point of 79 hours of non-stop play (at the time of writing this post).
 

Danieljohn

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The PD1515 seems to be made by ferranti . Ferranti used to have only F instead of ferranti written

1.God Bless you abundantly Yugaaa !

2.Ferranti had manufacturing company in Hong Kong as well? bcuz "F 801 PD1515 HONGKONG" was mentioned on the Transistors.

I am thinking cosmic might have imported them from the UK .

3.No Doubt !

4.my 70's Cosmic LAB-3000 Stereomaster Amplifier had "HUNTS" (rectifier) Capacitor from UK & Still has "LILLY" Capacitors from Japan just as NOBEL Japan potentiometers.
 

Danieljohn

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Cosmic LAB-3000 Stereomaster Amplifier cover was completely sealed type I don't this could be the reason but can't say for sure.

Might be sealed , but humidity temperature can wear down the parts . The trimmers are good for adjusting a few times . After that the carbon wears out . Best way is to spray a bit of wd40 and coconut oil to keep it working . I do not know if contact cleaner sprays are avaliable these days .

Thanks Yugaaa for being Supportive !

I'll try to keep them working after changing them by WD40 & Contact cleaner.

Ok even if it's not failed dont you think they must have got affected by the transistor, Speaker, VU meter failure?

If they are working then it is fine . Getting equivalent parts might be cumbersome .

Yeah !

Capacitors are 3000uf 60V so I would like to know to what extreme level we can go in choosing capacitors which can be accommodated within the amplifier.

Trying to get a similar size one is the most important thing . value can even go upto 4700 uf/63v

A.Yes ! Size matters or else our choice of caps won't fit within the Amplifier. hahaha

B.Just like higher Micro Farad/uf, can't we use higher voltage capacitor of 400-500V?

C.If used what are the drawbacks?

Ok but 2N3055 doesn't work? Bcuz I already bought them. Anyway I'll get 2N3773 as well kindly suggest which company ones.
ok .

I got confused with the bux39 . Seems like the 1515 is a darlington .

A.Really? a Darlington? Is this type of Transistor can be used wher bipolar transistor are implemented ?

B.Is Darlington superior to Bipolar?

Btw I didn't mention that right channel is in working Condition.

A.Is it possible to measure voltages ?

B.I also see fuses blown .

C.I am assuming the fuses blew on the left channel ?

A. Of right Channel? If so I'll ask uncle to check.

B.Just blown fuses can lead to such a catastrophic failure of one side channel?

C.Don't know but as I said previously everything blew in left channel except the fuses I guess or else the catastrophe could have not happened. :-(
 

Danieljohn

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Thanks Dear Reuben Sir,
For sharing your Experience & Enlightening us with the Consequences using Original Transistors.

A note from my experience. I have finished restoring a badly tampered with NAD 3020 which had loads of Jugaad repairs done on it. One of the 2N3055 output transistors, the one on the left channel, had been replaced with a Chinese one. This channel was sounding dull and there was clear channel imbalance as a result I had a Motorola 3055 transistor which i had kept in my collection as a replacement for my 3020 and was able to replace this Chinese 3055. The moment this replacement happened, the concerned channel returned to normal the channel imbalance disappeared. So in this case, using an original Motorola replacement did the trick.
A. I was suggested by Cosmic Tech Head to use CDIL 2N3055 as these never were duplicated.

B.I believe the Aluminium cover Motorola 2N3055 can't be a counterfeit ones am I right or wrong about it ? Bcuz these were made only in 60-70's I believe.

Alternatively, the driver transistors on the power stage of this amplifier had also been replaced by local ones. The NAD 3020 classic design uses the 2N6551 - 2N6554 pair. These are classic transistors and not easy to get in the spares market. I was in touch with a vendor in the United States who was asking for $50 including shipping for 2 pairs. Hence I decided to look at alternates. I first tried 2 pairs of BD139 - BD140 with good results. While the gain and presentation sounded great, I was not completely satisfied with the outcome as that "zing" factor, which the 3020 is famous for, seemed to be missing. I did some research by trying different transistor combinations and final arrived at the answer, which was the MJE 2955 - MJE 3055 pair. Though the pin configuration was a bit different and hence I had to juggle around a bit, but the outcome was to my satisfaction. This is the earliest model of the NAD 3020 with a base-mounted standing Transformer and a back mounted PSU board.

What would you suggest to me as a equivalent to PD1515 ? & I'm sure you must be knowing about the Driver Transistors used in Cosmic LAB-3000 Stereomaster Amplifier Sir. If I don't get the original Driver Transistors would you share your experiences trying other driver transistors which was satisfactory to you in Cosmic LAB-3000 Stereomaster Amplifier ?

To my ears, its now sounds so nice that I am enjoying its burn in with 24 hours music at home, we are now at the point of 79 hours of non-stop play (at the time of writing this post).

That's Wonderful & Lovely !
Wish I was ther with you Dear Ruben Sir. :-D
 
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reubensm

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I grew up in a household where our father (an old school engineer) was into building a lot of stuff. He had built this Mullard Circuit based on a 3055 pair (per channel) as output transistors, with the pair of SL100, SK100 driving these, the pre-drivers, if I remember correctly being the good old BC148B and BC158B. As you rightly mentioned, it was quite common for Philips circuits and Mullard circuits to get cloned in those times. My father even built a clone of this famous amplifier from the 1960s, based on the AD161, AD162 pair. That amplifier is still in service today.

Before we get into further discussion about your amplifier, would be great if you can share a clear pic of all the output transistors (both channels) in one pic.

From your pics, it is evident that Cosmic has used SL100-SK100 pairs as driver and pre-driver transistors. If this is the case, both output transistors for each channel are likely to be NPN transistors. The BUX39 transistor is of course a NPN transistor. It would be good to test the PD1515 transistor of the working channel and ascertain whether it is a PNP or NPN transistor. Let me know what you find out.
 

Danieljohn

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I grew up in a household where our father (an old school engineer) was into building a lot of stuff. He had built this Mullard Circuit based on a 3055 pair (per channel) as output transistors, with the pair of SL100, SK100 driving these, the pre-drivers, if I remember correctly being the good old BC148B and BC158B. As you rightly mentioned, it was quite common for Philips circuits and Mullard circuits to get cloned in those times. My father even built a clone of this famous amplifier from the 1960s, based on the AD161, AD162 pair. That amplifier is still in service today.

Quite a Amazing childhood then Sir,
AD161 & 162 are Germanium right? If so can my Amplifier also be changed to Germanium Transistors? and what would be that output of most powerful Germanium Transistors ?

Before we get into further discussion about your amplifier, would be great if you can share a clear pic of all the output transistors (both channels) in one pic.

From your pics, it is evident that Cosmic has used SL100-SK100 pairs as driver and pre-driver transistors. If this is the case, both output transistors for each channel are likely to be NPN transistors. The BUX39 transistor is of course a NPN transistor.

But is ther a Possibility of being PNP Germanium Transistors?

It would be good to test the PD1515 transistor of the working channel and ascertain whether it is a PNP or NPN transistor. Let me know what you find out.

Ok for Sure !

Thanks soo much Dear Ruben Sir,
For being a Great help ! 2018-11-14 18.02.10.jpg
 
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reubensm

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That picture of all 4 output transistors reveals the plot. Your amp originally had 4 x PD1515 output transistors. One of them would have been replaced and that's why the BUX39 from Electronics Corporation of India (ECIL, with the EC logo) features there. It is also now confirmed that the PD1515 transistors must surely be NPN. That also ties up with the fact that your drivers are SL100-SK100 pairs.

Now to my suggestion (again this is my humble opinion and what I would have done if I were to fix this Indian legend):

You are not likely to find the PD1515 transistor any more. However you will find the MJ 15015 (or MJ 15015G) metal cap transistor which can be used as a direct substitute.

This transistor was manufactured originally as the PD 15015 transistor but these days, you are most likely to find the MJ version. Just as we come across the 2N 2955 - 2N 3055 Pair (with 2955 being PNP and 3055, NPN), the 150xx series appears as MJ 15015 - MJ 15016 (with 15015 being NPN and 15016, PNP). Also if you look at the data sheets and do a comparison, the MJ 150xx series comes with same specs as the 2N3055A (which has greater tolerances when compared to the 2N3055). Please take a look at this.

Hope this helps :)
 
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