Hello this is rishiguru. I am a newbie and have very little knowledge about DIY. My friends audio amplifier is broke we have opened the cabinet and found
that a pair of A1943/C5200 is used per channel of the two channel amp.
Now, one of the C5200 is burnt, so below is the image of the other pair(which seems ok).
Can anybody tell the name of the manufacturer & the specs like power output, voltage and current ratings of this pair. The amp is rated 125 watts X 2. the transfo outputs +/-30V to this two pair of transistors. Is the current rating 5A (not quoted on the transfo)?
It also have 4, 4700uF, 50V capacitors used as ripple filters
Also cannot find CKT brand name? Where we can buy this exact pair?
Kindly help. Thanks in advance.
that a pair of A1943/C5200 is used per channel of the two channel amp.
Now, one of the C5200 is burnt, so below is the image of the other pair(which seems ok).
An externally hosted image should be here but it was not working when we last tested it.
Can anybody tell the name of the manufacturer & the specs like power output, voltage and current ratings of this pair. The amp is rated 125 watts X 2. the transfo outputs +/-30V to this two pair of transistors. Is the current rating 5A (not quoted on the transfo)?
It also have 4, 4700uF, 50V capacitors used as ripple filters
Also cannot find CKT brand name? Where we can buy this exact pair?
Kindly help. Thanks in advance.
Last edited:
2SA1943 and 2SC5200 are Toshiba transistors, also made by Fairchild. DigiKey has them. If you prefer another distributor, a search engine should locate others.
thanks. then why this CKT is written? Here is the magnified pic of the above transistors. Are they Toshiba? They do not seem so.
2c95f.jpg at Free Image Hosting
Also having left speakers of CKT brand and Toshiba ones on right can produce different sound signatures in the speakers?
Can any one tell me where I can get this specific pair (Same brand & model)?
Last edited:
Just order 2 each of Toshiba or Fairchild and replace all 4.
Order from Digikey or Mouser and you will not get counterfeit models.
Order from Digikey or Mouser and you will not get counterfeit models.
The reason it broke could well be that those "CKT" marked outputs were fakes.
Amplifiers usually never just fail spontanously one day unless something like a lytic went bad first.
However 30VAC means the rails are at 43VDC and the SOA of these outputs wont allow for more than around 1A if even that, at that voltage = this amp should never see anything less than a 8 ohm load.
If its driving 4 ohm speakers, i'd drill and tap 4 extra holes and double up on the output transistors, or replace them with something beefier like MJL4281 and its companion MJL4302.
Amplifiers usually never just fail spontanously one day unless something like a lytic went bad first.
However 30VAC means the rails are at 43VDC and the SOA of these outputs wont allow for more than around 1A if even that, at that voltage = this amp should never see anything less than a 8 ohm load.
If its driving 4 ohm speakers, i'd drill and tap 4 extra holes and double up on the output transistors, or replace them with something beefier like MJL4281 and its companion MJL4302.
There are a number of copies which are not fakes, and most likely licenced, I can think of Fairchild for instance. As semi said, you have to get these from a trusted source as the real fakes are everywhere these days.
Fairchild do not mark their versions as "Toshiba 2sa1943".
Fairchild's versions cannot be copies, nor fakes, nor counterfeits.
Fairchild's versions cannot be copies, nor fakes, nor counterfeits.
Absolutely, I did not mean to leave room for confusion, Fairchild parts will have their own logo and markings... When I deal with some of the smaller suppliers around me, I insist on the Fairchilds as the Toshiba ones they stock are all fake... Tiny die stuck in a giant transistor.
well the amp is rated:
125W X 2 @ 4ohms
100W X 2 @ 6ohms
80W X 2 @ 8ohms
The transformer is sizebale. From what i heard you need a minimum of 300Va tranfo to pump out 250 watts of power @ 4 ohms. So, i was thinking +/-30V, 5A from the transfo. (ampere not quoted on the transfo)
the transfo have two secondaries +/-30V to the power amps (two sets of the above transistors) & +/-15V to the op amp circuit.
Below is the link to amplifier internal (hope it helps):
http://www.freeimagehosting.net/219d5
The op amps (3 units) are Texas Instruments TL072CP. Are they dual op amps. Just out of natural curiosity is the transfo 300+ VA?
Last edited:
local made. do not belong to any world famous company. The amp weighs 9 kilos though.
The transformer have a diameter of 11 cm and a height of 5.5 cm
Last edited:
OOh, I only saw the pic now, bad news man, with those tiny heatsinks it is only a matter of time before it eats more transistors, better stock up, or get bigger a nice fat heatsink on the rear.
Heres what heatsinks for a 100-150W into 4 ohms amp atleast should look like: http://i.imgur.com/TMC82.jpg
An Antek transformer of similar dimensions is rated at 200VA.
The original transistors may be from KEC, a Korean semiconductor manufacturer. Their type numbers are KTA1943 and KTC5200. The website KEC does not list either one now so they may be obsolete. Best to buy a full set of Toshiba parts and change them all.
Given the power rating of the amplifier, the transformer and heatsinks are all on the small side. Try to keep the area around the heatsinks free of obstructions and maybe let the heatsinks extend past the shelf on which the amplifier sits for best air flow. Even then, I would not push the amp too hard.
Heh, the preamp PCB looks like one of Rod Elliots. The power amp design looks like it might be a copy of his P3A too.
Either get genuine Toshiba 2SA1943/2SC5200, or STMicro's versions, or Fairchild FJL4215/FJL4315 (also sold as Fairchild 2SA1943/2SC5200), or Onsemi MJL4281/4302.
Failing all of those, Onsemi MJL21193/4.
And yes, those heatsinks are too small for 100W into 4 ohms continuous duty. I cannot see the driver transistors but they should be TO-220 packages and on heatsinks of their own.
Either get genuine Toshiba 2SA1943/2SC5200, or STMicro's versions, or Fairchild FJL4215/FJL4315 (also sold as Fairchild 2SA1943/2SC5200), or Onsemi MJL4281/4302.
Failing all of those, Onsemi MJL21193/4.
And yes, those heatsinks are too small for 100W into 4 ohms continuous duty. I cannot see the driver transistors but they should be TO-220 packages and on heatsinks of their own.
That is a Norge amplifier, you can see it on the PCB print.
Someone did tell me that brand (and most other hifi manufacturers in this part of the world) uses some public domain designs - though never seen an internal shot of one.
Norge Audio
He does have some decent products though, our very own sumanjana has designed one of his newer speakers.
I guess it goes with the business. I've seen a $500 Japanese amplifier from a boutique brand using a TDA1562 and a 40VA transformer. Not much original talent, just a money-making racket 🙂
Someone did tell me that brand (and most other hifi manufacturers in this part of the world) uses some public domain designs - though never seen an internal shot of one.
Norge Audio
He does have some decent products though, our very own sumanjana has designed one of his newer speakers.
I guess it goes with the business. I've seen a $500 Japanese amplifier from a boutique brand using a TDA1562 and a 40VA transformer. Not much original talent, just a money-making racket 🙂
sangram, can you tell me from where my friend can get those CKT made transistors? Do you think that transformer is 300VA?
From the info i have got these transistors are manufactured in Taiwan.
Last edited:
Friendly advice: Change all 4.
Toshibas are pretty widely available and will anyway be better than the CKTs. You can buy the Toshibas in every electronic market in India. Worst case, write to Shyam and he will send you one pair of whatever he has in stock. at worst, it'll blow up under similar conditions.
I've used the Tosh's as 'blind' replacements in many amps <60W and they get along well with a few adjustments. Not saying they will be genuine. Most transistors in India are fake.
That transformer will be 150VA at best. One pair 1943/5200 on that heatsink will likely be good for 40W/ch. So transformer is fine. What model of Norge is this one?
Toshibas are pretty widely available and will anyway be better than the CKTs. You can buy the Toshibas in every electronic market in India. Worst case, write to Shyam and he will send you one pair of whatever he has in stock. at worst, it'll blow up under similar conditions.
I've used the Tosh's as 'blind' replacements in many amps <60W and they get along well with a few adjustments. Not saying they will be genuine. Most transistors in India are fake.
That transformer will be 150VA at best. One pair 1943/5200 on that heatsink will likely be good for 40W/ch. So transformer is fine. What model of Norge is this one?
That is probably the combustion limit.
A 125W continuous amplifier in Class AB mode at 65% efficiency will be dumping something like 150-160 watts as heat. To keep the heatsink at a reasonable temperature at peak dissipation (somewhere near the 33% power output point) you need a heatsink of about 0.4 C/w.
Such a heatsink is usually much larger than the one shown. About twice as large, I would think. I'm not surprised the transistor exploded. The 150W peak dissipation of the transistor would be easily exceeded at the temperatures it might have been running under given the size of the heatsink.
The rated power output is extremely ambitous. One might say it's wishful thinking. The Toshiba transistors will at least be a bit more durable than these CKT ones.
A 125W continuous amplifier in Class AB mode at 65% efficiency will be dumping something like 150-160 watts as heat. To keep the heatsink at a reasonable temperature at peak dissipation (somewhere near the 33% power output point) you need a heatsink of about 0.4 C/w.
Such a heatsink is usually much larger than the one shown. About twice as large, I would think. I'm not surprised the transistor exploded. The 150W peak dissipation of the transistor would be easily exceeded at the temperatures it might have been running under given the size of the heatsink.
The rated power output is extremely ambitous. One might say it's wishful thinking. The Toshiba transistors will at least be a bit more durable than these CKT ones.
- Status
- Not open for further replies.