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PD1515

Aaron Nikhil

New Member
We don't.
Yes Dear Nigel we Don't !

1. Or else ther would be atleast one Germanium Transistor Amplifier for us not just for Musicians.

2.But I somehow Loved the Germanium Transistors PP Circuit Amplifier Sound very much !

that web page made very little sense - basically it said what we all know.
Yes !

it's become quite fashionable among some musicians to use old style germanium based distortion pedals.
1.The below content caught my attention in that webpage Dear Nigel.

http://avalonadvancedmaterials.com/news_media/exploring_clean_tech/index.php?content_id=845
"Silicon transistors tend to sound more like old tube amps being pushed hard. In contrast, germanium transistors produce a warmer, smoother, more-ear pleasing distortion. Germanium transistors also seem to react well to changes in volume and can detect small changes in signals - hence the electronics are more sensitive."
2. I believe ther is only one Distortion which is pleasing to our ears & that is 2nd/Even order Harmonic Distortion but this particular distortion has nothing to do with the type/kind of Transistor used. Infact it's a Trait of Single-Ended Circuit Topology but I could be wrong also.

3.The Graceful clipping characteristic of Vacuum Tubes in Germanium Transistors isn't fashionable for Musicians, infact ther is a similar gain device's Amplifiers available now (Maxonic SD-011/013, First-Watts's SIT-1/2/3, Digital Do-Main (Yamaha B1), FAL SIT-7K/5K) with tube like clipping characteristic for Audiophiles, not for Musicians though !

Thanks Dear Nigel,
for correcting & Facts ! :)

& Thanks to All the Dear fellow Fm's who would be informing Mr.Fezder about me and my requirement of his Linear PSU's PD1515 Transistors.
 
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Aaron Nikhil

New Member
Dear Rjenkinsgb, Dear Nigel, Dear Most Helpful Member,
Kindly let me know whether this 1515 Transistor can be used as an equivalent to PD1515?
1. Packaging is different.
2. I was told that it's a mosfet.
3.Used in high power DJ Amplifiers in india.

Thanks in Advance !IMG-20181030-WA0012.jpg
 

rjenkinsgb

Active Member
No.
Your amp definitely uses bipolar transistors, as bipolar replacements you have mentioned do function correctly at least for a short time.

A FET needs very different bias circuits to a bipolar type; they are not interchangeable without also re-designing the driver stages of the amp.

The MJ802 should work well.
 

Aaron Nikhil

New Member
No.
Your amp definitely uses bipolar transistors, as bipolar replacements you have mentioned do function correctly.
1st Thanks soo much for preventing a Disaster Dear Rjenkinsgb !

at least for a short time.
2. How to make them work for a long time Dear Rjenkinsgb?
3.what all are to be considered at what stages pls let me know.

Thanks Dear Rjenkinsgb for being soo Supportive & Helpful.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Do you have a schematic for the amplifier?, or can you draw it out?.

You don't fit replacement transistors by trying to source ones to match the originals, but ones to match the circuit.

As far as amplifier repairs go, it's VERY rare for replacing the output transistors (even with the correct ones) to effect a long term repair - often other components have either caused the failure in the first place, or have been damaged by the failure. Simply replacing the output devices just means they blow again fairly quickly, and the original fault could even be intermittent. It's also crucial to make sure the quiescent current is correctly adjusted, as again it's likely to destroy the new output transistors otherwise.
 

Aaron Nikhil

New Member
Do you have a schematic for the amplifier?
No as of now Dear Nigel,
But Cosmic Company Technical Head would be sending me a scanned copy of my Amplifier model Schematic very soon.

or can you draw it out?.
No I'm not that Good at these things.

You don't fit replacement transistors by trying to source ones to match the originals, but ones to match the circuit.
Words aren't enough to Appreciate the Philosophy in your approach towards my Amplifier problem Dear Nigel I'm very impressed. :)

As far as amplifier repairs go, it's VERY rare for replacing the output transistors (even with the correct ones) to effect a long term repair - often other components have either caused the failure in the first place,
Yes ! Infact I spoke to one of the Gentlemen who use to service these things for past three decades told me that even driver transistors are to be replaced as their erratic behaviour caused the output transistors to go off.

or have been damaged by the failure.
No Doubt ! that's the reason BUX39 blew off just weeks after amp got serviced.

Simply replacing the output devices just means they blow again fairly quickly,
Absolute Fact !

the original fault could even be intermittent.
Must Be !

It's also crucial to make sure the quiescent current is correctly adjusted, as again it's likely to destroy the new output transistors otherwise.
Thank God this thing I'm assured by my current Tech Guru who presently taking care of my Amplifiers by giving me a lecture on the significance of quiescent current adjustment.

Thanks Dear Nigel,
For Being soo Helpful & Evoking certain Philosophical approach towards these kind of things.
 

Aaron Nikhil

New Member
By using a better rated transistor - the MJ802
Ok "Rated" means superior parameters than the original Transistor right? Dear Rjenkinsgb.

not a 2N3055!
I Promise I won't go for 2N3055 not bcuz of the things we felt about them but your suggestion about MJ802G makes lot of sense to me as I Believe one of my other Amplifier also has these Transistors but not sure about the Complimentary setup being employed like Mr.Most Helpful Member once pointed out if not is it Good or Bad? & in what way?

Thanks Dear Rjenkinsgb,
For making my decisions easy & simpler.
 
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Aaron Nikhil

New Member
Dear Rjenkinsgb & Dear Nigel,
What's your take on 2N3773 Transistors?
Pls let me know as I might be using them in place of PD1515.

Thanks in Advance !
 

rjenkinsgb

Active Member
I've use 2N3773 transistors in industrial gear; they have a higher voltage rating than the MJ802G but lower minimum gain and lower current rating.

Without knowing the full details of the amp output stage drive circuits and what voltages it works on, it's impossible to say for sure which is best; however the MJ802 is nearer to the BUX39 in ratings & presumably someone fitted that for a reason.


You apparently have schematics on the way, so best to wait for them rather than guessing.
 

Aaron Nikhil

New Member
I've use 2N3773 transistors in industrial gear; they have a higher voltage rating than the MJ802G but lower minimum gain and lower current rating.
1.How important are minimum Gain & Current Rating ?
2.which particular electrical Characteristic makes the Transistor Sound Amazing ?
Without knowing the full details of the amp output stage drive circuits and what voltages it works on, it's impossible to say for sure which is best;
Ther was a PD1515 Data gif in Thread started by our Dear fellow forum member Mr.Fezder which was posted by Mr.Ericgibbs so can't you make out which Transistors would be appropriate by that data? Dear Rjenkinsgb.AAesp01.gif

The MJ802 is nearer to the BUX39 in ratings & presumably someone fitted that for a reason.
1.yes bcuz it's an Equivalent of PD1515 Dear Rjenkinsgb.

2.Even now after a decade when I enquire about PD1515 locally they are saying the Equivalent BUX39 is available.

You apparently have schematics on the way, so best to wait for them rather than guessing.
1.Yes I hope depending on schematic you will be able to suggest the Best Transistors ever for my Amplifier.
2.Dear Rjenkinsgb what's your Take on BUX39?

Thanks Dear Rjenkinsgb for your views on 2N3773 & being Supportive. :)
 
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Aaron Nikhil

New Member
Dear Rjenkinsgb, Dear Nigel,

1. what's your Take on BUX39 ?
2.is BUX39 superior to 2N3055 or 2N3773 ? if so in what way?

Thanks in Advance !
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Dear Rjenkinsgb, Dear Nigel,

1. what's your Take on BUX39 ?
2.is BUX39 superior to 2N3055 or 2N3773 ? if so in what way?

Thanks in Advance !
The BUX39 is a switching transistor, so not designed for audio use.

The 2N3773 is designed for high power audio, the 2N3055 for medium powered audio.

The PD1515 could well just be an in-house number, as there's no data about it.
 

rjenkinsgb

Active Member
What does "In-house" number mean?
It means where equipment makers re-number standard components with their own made-up numbers, so you cannot get replacement parts anywhere else.

It was extremely common in the 70s and 80s, when most things used standard parts.
It also prevented easy copying by other manufacturers.

Now many things use specially made ICs etc., anyway, they often cannot be repaired except by the maker (or with parts bought from them), so "in-house" numbers are not so common.


This is an example where the ICs have in-house numbers - some with the original numbers still visible, others with them removed or masked.
https://www.picclickimg.com/d/w1600/pict/262107103681_/General-Electric-Mark-Century-1050-Controller.jpg
 

Nigel Goodwin

Super Moderator
Most Helpful Member
It means where equipment makers re-number standard components with their own made-up numbers, so you cannot get replacement parts anywhere else.
To be fair, that wasn't the only reason.

Another, less harsh, reason is that it allows a manufacturer to source parts from different manufacturers, and have them stamped with the same number thus keeping the spares situation nice and simple. This means that if one manufacturer is unable to supply the part you need, you have various others sources for the 'same' part.

As someone who repaired lot's of stuff with in-house numbers it made no difference, as I've already said you don't replace transistors based on their specification (which you can't find out for in-house numbers), you simply replace them based on what they are doing, and what their function is.

Interestingly the now defunct German manufacturer company Grundig continued to make IR preamps on small PCB's in metal screening boxes for years after everyone else had moved to TSOP chips. As we were a MAJOR Grundig dealer we asked them why this was? (as it obviously cost them much more), the reason was simply a lack of different manufacturers, they weren't willing to place their entire production in the hands of one component manufacturer.
 

Aaron Nikhil

New Member
That's Interesting to know Dear Rjenkinsgb & Dear Nigel do you both think that was the case in my issue?
I can't believe that bcuz PD1515 was available in various countries !
 

Aaron Nikhil

New Member
Dear Rjenkinsgb, Dear Nigel,
Dear Most Helpful Member,

1. I found this link http://forum.db3om.de/ftopic12215.html related to PD1515 but couldn't make out from which forum the thread is from. Kindly help me find out which forum is it.

2. Does TO-3 Housing with Aluminium Cover any Good than Steel cover ones?

3. I feel ther can't be counterfeit Motorola 2N3055's with Aluminium cover.

Thanks in Advance !
 
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