Toshiba Ouput Tranistors 2SD424 & 2SB554 (many Adcoms)

ben62670

jakelm wrote: »

Very easy way to find out if its common ground. Ben, you already have the top off. Put the meter to it.

Don't even have to take the top off. Just take an MM, and check for Zero ohms between ground, and as a safety precaution tie the grounds together anyways;)

jakelm

ben62670 wrote: »

Don't even have to take the top off. Just take an MM, and check for Zero ohms between ground, and as a safety precaution tie the grounds together anyways;)

Did you do it? Did you find out if it was common ground?

unc2701

GV#27 wrote: »

Apparently you don't suffer from alziemers to remember all of that.I have to stick to the numerically much simpler Bryston line,2B, 3B,4B,6B,9B all common ground. 7B,14B,24B,28B non common ground and not strappable.

Wait, WTF is a 24B? That's one I don't know.

BTW, there was briefly a 6b monoblock that turned into the 7b.

Lowell_M

heiney9 wrote: »

Cool can't wait. I'm finally over my cold/head sinus congestion and can hear almost normal again. You can bet these will be demo'd/used at our next area Polk gathering which should be coming up soon (sorry for the slight derail)

SWEET!!:D

Systems

unc2701 wrote: »

Wait, WTF is a 24B? That's one I don't know.

He He good catch I was wondering if anybody would notice that one.;)It is VERY new and essential a 28B that has a bigger power supply (yes I said bigger)so that it can deliver even more power into to 4 ohm and below impedances.

BTW, there was briefly a 6b monoblock that turned into the 7b.

Yes the original 6B was a short lived model from the late 80's.

ben62670

jakelm wrote: »

Did you do it? Did you find out if it was common ground?

Non common Ground... till I tied the grounds together. You know it tested this thing at high output CD skipping around 122d limited turning it up any more. Remember 2.6ohm. Try that with some silly switching power supply amp:D

jakelm

ben62670 wrote: »

Non common Ground... till I tied the grounds together. You know it tested this thing at high output CD skipping around 122d limited turning it up any more. Remember 2.6ohm. Try that with some silly switching power supply amp:D

LOL.. Thats what I have with my mains, 2.6ohms, on my Hafler.

Speaking of amps, this might sound like another dumb question, but why does your amp have so many transistors? Mine has maybe 4. Are the transistors in series, smaller? So more is needed?

ben62670

jakelm wrote: »

LOL.. Thats what I have with my mains, 2.6ohms, on my Hafler.

Speaking of amps, this might sound like another dumb question, but why does your amp have so many transistors? Mine has maybe 4. Are the transistors in series, smaller? So more is needed?

Each one is rated for a certain amount of currant. The more you have the more currant you can run through them. Also the more you have the safer it is for the chips to cool. Only so much heat can transfer from a certain size package. I think this is expressed as SOA. If you google soa, and transistor you should get a better idea than I can give. No the trannies are parallel, and there are 2 sets for each channel. One is push, and one is pull. NPN/PNP

jakelm

ben62670 wrote: »

Each one is rated for a certain amount of currant. The more you have the more currant you can run through them. Also the more you have the safer it is for the chips to cool. Only so much heat can transfer from a certain size package. I think this is expressed as SOA. If you google soa, and transistor you should get a better idea than I can give. No the trannies are parallel, and there are 2 sets for each channel. One is push, and one is pull. NPN/PNP

I guess thats why my Hafler gets so warm, larger trannies. And yours has more wattage, more trannies. If your had less trannies but bigger, it would need a huge cooling system. Just like a more powerfull CPU needs more cooling, because of the increase in transistors.

I read a great tutorial on transistors. I learned from the begining with the crystal and the "magic" spot, the different semiconductors, like silocon and germanium, n-type and p-type doping, reverse bias and forward bias. How yesturday was point contact transistors and now we use FET transistors.

All because of this thread... Thanks...now I'm not getting any sleep at night...:p

Systems

jakelm wrote: »

I guess thats why my Hafler gets so warm, larger trannies. And yours has more wattage, more trannies. If your had less trannies but bigger, it would need a huge cooling system.

The amount of heat generated depends on bias current and heat sink sizing.Amps with multipule paralleled outputs run with hi bias currents will also get hot.

jakelm

GV#27 wrote: »

The amount of heat generated depends on bias current and heat sink sizing.Amps with multipule paralleled outputs run with hi bias currents will also get hot.

Does the p-type differ from the n-type in heat? Or does the heat of the transistor, dedend on how fast the neutrons travel from the sorce to the drain?

Systems

jakelm wrote: »

Does the p-type differ from the n-type in heat?

It shouldn't in a push pull circuit with matched devices.

Or does it matter purely on how fast the neutrons travel from the sorce to the drain?

:eek:

jakelm

GV#27 wrote: »

:eek:

Oh OHHH>..Did i say something stupid again?:p

unc2701

GV#27 wrote: »

He He good catch I was wondering if anybody would notice that one.;)It is VERY new and essential a 28B that has a bigger power supply (yes I said bigger)so that it can deliver even more power into to 4 ohm and below impedances.

Bigger PS????? Holy hell. Makes me think of this auction I just saw on ebay:
http://cgi.ebay.com/Amveco-120V-8KVA-Toroid-Toroidal-Power-Transformer-HiFi_W0QQitemZ110215277363QQihZ001QQcategoryZ4660QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Systems

unc2701 wrote: »

Bigger PS????? Holy hell. Makes me think of this auction I just saw on ebay:
http://cgi.ebay.com/Amveco-120V-8KVA-Toroid-Toroidal-Power-Transformer-HiFi_W0QQitemZ110215277363QQihZ001QQcategoryZ4660QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

8000VA:eek:that qualifies as big.I think the 28B transformer is 2kVA and Im not sure by how many VA but the 24B's will be bigger,plus more filter capacitance.

Systems

jakelm wrote: »

Oh OHHH>..Did i say something stupid again?:p

Sorry jake I'm still scratching my head to find an answer to that one.:D

jakelm

GV#27 wrote: »

Sorry jake I'm still scratching my head to find an answer to that one.:D

OK...lol.. I ment to say electrons not neutrons..sorry.

The gate has a positive voltage charge, which when applied to the semicunductor, attracts the electrons to it, thus creating a current flowing from the source to the drain. The more voltage the gate supplies the more current flows through the transistor. The more current, the more energy, the more heat.


I love this game. See,,,,,:D

http://nobelprize.org/educational_games/physics/transistor/function/gate.html

Systems

jakelm wrote: »

The more current, the more energy, the more heat.

Bingo

I love this game. See,,,,,:D

http://nobelprize.org/educational_games/physics/transistor/function/gate.html

thats cool.

jakelm

Another night up, 3.5 hours of sleep, now I'm at work. This time I was reading about transformers, and no, not the movie.

Tesla is so cool.

I always thought transformers convert ac current from the wall socket , to dc current for the electronics. But it seems to just change the voltage or amps, depending on the wire turns.

ka1bbg

Hi, new member, saw ben62670 has transistors, sj2520 can be replaced by 2sb554, and sj2519 can be replaced with 2sd424 transistor......in a marantz250m.....i need a set of transistors for 250m. cul brian f.

ToJo

Hi!
I´m new to this forum and found this thread when I was looking for replacement transistors for my old Quad 405. This amplifier use 2SD424 or RCA 17556 transistors.
Are there still transistors awailable and would you ship to Sweden?

Best Regards
Tomas Johansson

ben62670

Welcome to Club Polk. I am out of the 424's. All I have left is the 554's
Sorry
Ben

geobiz

Ben,

How many 554 do you have and price please. Will be used in 555 and 585's. How did you do the matching since I have a few 424's. thanks, George

ben62670

Hey George I have about 24 matching 554's left. My email is my username @ yahoo dot com
Thanks
Ben

sittingplow

hopefully ben got the transistors 2sb554 and 2sd 424 how do i get a hold of you i see you have lots very interested in purchasing some mail me im from canada ontario back yard repair man looking forward to hear from you

ben62670

They are all gone except just a few of the 554's.

docrw

Hey Ben,
Would you give us your contact information so we can contact you on the Tranny's please. I'd like to get a complete matching set for my 585. Would also like to ask you some other questions.
docrw@yahoo.com
David

I just bought a $hit load of these transistors. I know they fit Adcom GFA-585's for sure, and I think many more. Let me know if you need some. I will be beta matching these to sell as sets.
Thanks Ben

Va2k

Hi, I live in Cambridge, UK & wondered if 1st of all you have these still? 2nd would you be willing to post to the uk? 3rd if so how much would you want for 4 matched pairs of 2SD424's? including the postage to said location??
Regards Joe......

P.S They also are used in QUAD 405 MK1 as a complimentary NPN pair, mabe the mark II uses them also?

irishboym4

Do you still have any of these? i need like 10 matched pairs of each(2sb554+2sd424). could you get me a price to ship that to 94588 in california?

Brendan

TECHNOKID

ben62670 wrote: »

They are all gone except just a few of the 554's.

Too bad you didn't have more you'd have got rich :cool: Thoses transistors are sure popular!