I can not tell if they are genuine or not. Certainly look new and not old or tarnished.
I see in another thread someone weighed them and found out there were differences.
Not sure if that is a good way to tell because they could have changed the package construction during there run.
The best way to tell is to measure them and compare the measured specs against published.
BTW where did you get the mosfet's from? just curious.
I see in another thread someone weighed them and found out there were differences.
Not sure if that is a good way to tell because they could have changed the package construction during there run.
The best way to tell is to measure them and compare the measured specs against published.
BTW where did you get the mosfet's from? just curious.
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Seeing that your source for those output transistors is chinese - I can guarantee that they are fake - unless they are obvious pulls from scrap gear. Even with genuines - you would need them matched.
I did a ton of research when sourcing TO-3´s for a DH500 - including ordering samples from a few china sources. Curve tracing the supposed Hitachi against the originals was worth the money in laughs.
By now I´m sure there are chinese festivals in my name - paid for by all the counterfeit crap I´ve bought from them.
Get a refund from that company - and go with the Exicons.
I did a ton of research when sourcing TO-3´s for a DH500 - including ordering samples from a few china sources. Curve tracing the supposed Hitachi against the originals was worth the money in laughs.
By now I´m sure there are chinese festivals in my name - paid for by all the counterfeit crap I´ve bought from them.
Get a refund from that company - and go with the Exicons.
Yeah that is not very encouraging from your experience. Good advise, hopefully the 3 months has not expired.
I know that Exicon sells matched pairs with the "S" suffix. Need to ask them about selling sets of 3 matched devices for the DH-500 & P230 etc.
I was looking at the ecf10n(p)20 spec's they have a mistake, I notified them the typical transfer characteristics graphs have the wrong "x" labeling, should be Vgs as Vds is a constant 10V.
Sounds like member @parabolic knows his mosfets, I wonder what the grading spec/criteria/tolerances would be? I assume they are graded by Vgs at some specific current, probably in the 100mA range? Probably can set Vgs at 1V, measure the drain current and match devices within 10% tolerance is my guess.
I know that Exicon sells matched pairs with the "S" suffix. Need to ask them about selling sets of 3 matched devices for the DH-500 & P230 etc.
I was looking at the ecf10n(p)20 spec's they have a mistake, I notified them the typical transfer characteristics graphs have the wrong "x" labeling, should be Vgs as Vds is a constant 10V.
Sounds like member @parabolic knows his mosfets, I wonder what the grading spec/criteria/tolerances would be? I assume they are graded by Vgs at some specific current, probably in the 100mA range? Probably can set Vgs at 1V, measure the drain current and match devices within 10% tolerance is my guess.
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So could these outputs also be the reason the DC offset adjustment pot does not work? Also, why doesn’t the protection circuit trip the relay with the high offset?
a good possibility.
I think this is a separate issue, like I said/asked before, mark up a schematic with the DC voltages you are measuring on the protection pcb.
Rsavas; this vendor will match sets for these amps. I have a set here in my dead DH500 that I’m holding onto.
Ed at Qua-Co in New Jersey is the vendor.
2SK134 2SK135 2SK176 2SJ49 2SJ50 2SJ56 ECF10N20 ECF10P20 EXICON SET | eBay
He actually worked for Hafler I’m told, has a different design of driver board also.
Ed at Qua-Co in New Jersey is the vendor.
2SK134 2SK135 2SK176 2SJ49 2SJ50 2SJ56 ECF10N20 ECF10P20 EXICON SET | eBay
He actually worked for Hafler I’m told, has a different design of driver board also.
I hope they appreciate your advertising.
I am aware of that vendor. I find it odd that they only list "N" & "P" devices but not matched sets knowing that they are required to be installed as both matched "N" & matched "P" devices as part of a repair or upgrade. I find it near useless in just buying a pair of "N" & "P". This vendor should inform the customer as such, if they do indeed know these design requirements.
I am aware of that vendor. I find it odd that they only list "N" & "P" devices but not matched sets knowing that they are required to be installed as both matched "N" & matched "P" devices as part of a repair or upgrade. I find it near useless in just buying a pair of "N" & "P". This vendor should inform the customer as such, if they do indeed know these design requirements.
The pin broke off, imo near impossible for the driver to do this, you have to treat it like an wild animal in order for it to do that. More tell tale signs of a questionable part.
Like said before, contact the vendor, show them, demand a refund, issue a case with eBay and even Paypal if you have too to get your full credit returned.
Like said before, contact the vendor, show them, demand a refund, issue a case with eBay and even Paypal if you have too to get your full credit returned.
You have to tell them that you are working on a Hafler, and they will match them. They don’t advertise that and some people seem to not be very resourceful it would seem.
Well the pin did not break off when I removed the mosfet, apparently the device blew up. The heatsink was black. I did hear something when I initially powered the amp up. I did not see any smoke and I could not see anything burnt on the driver board.
So being that the output is fried, do you think it was the board that caused it, or could it be a bad output? I don't want to install a set of Exicons and have them short out!
So being that the output is fried, do you think it was the board that caused it, or could it be a bad output? I don't want to install a set of Exicons and have them short out!
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@Rudes ... how are you isolating those transistors from the heat sinks?
I looked at your picture and didn't see anything like sockets, bolt insulators, or mica insulators or silicon grease in evidence...
Here is an illustration of the Minimum Mounting Scheme
The cases of TO3 transistors are also the collectors. In a power output stage the collectors are connected to the voltage rails... and the heat sink is likely grounded, leaving you with a dead short if they aren't properly mounted.
I looked at your picture and didn't see anything like sockets, bolt insulators, or mica insulators or silicon grease in evidence...
Here is an illustration of the Minimum Mounting Scheme
The cases of TO3 transistors are also the collectors. In a power output stage the collectors are connected to the voltage rails... and the heat sink is likely grounded, leaving you with a dead short if they aren't properly mounted.
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Ah, okay ... so long as they're not just bolted to the sinks.
The picture made it look that way ... my bad.
BTW are you using Arctic Silver?
That stuff can be conductive.
It's amazing on computer CPUs where there is no ground path through the heat sink but there are lots of places where the good old white silicon grease is a safer to use.
The picture made it look that way ... my bad.
BTW are you using Arctic Silver?
That stuff can be conductive.
It's amazing on computer CPUs where there is no ground path through the heat sink but there are lots of places where the good old white silicon grease is a safer to use.
Rudes
I´m starting to sound like some Exicon fan boy 🙂 - but your money is best spent there... I would recommend ordering directly from the UK - that way you have a wider selection in gradings etc. You should be able to recover some of the cost by selling the working original Hitachi´s. And if the chinese seller gives you crap - then file a fraud claim with your credit card company.
I applaud you for having come this far in rebuilding your Hafler- now it´s just one final hurdle and you´ll be swirling in juicy lateral mosfet goodness 🙂
I´m starting to sound like some Exicon fan boy 🙂 - but your money is best spent there... I would recommend ordering directly from the UK - that way you have a wider selection in gradings etc. You should be able to recover some of the cost by selling the working original Hitachi´s. And if the chinese seller gives you crap - then file a fraud claim with your credit card company.
I applaud you for having come this far in rebuilding your Hafler- now it´s just one final hurdle and you´ll be swirling in juicy lateral mosfet goodness 🙂
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Yes, thank you! Already contacted them, but I want to be sure that my driver boards are OK. Is there anyway for me to confirm this before installing Exicons? I would not want to damage these!
