I just wonder what for hitachi who is one of the most semiconductor producer would like to fake a transistors???
That's assuming Hitachi manufactured them.
Yamaha and NEC got into VFETs right after Sony started producing amps with the J18/K60.
Hitachi developed their Lateral MOSFETs series as an alternative, which was less costly in manufacturing.
Main reason why yours are not genuine.
Secondly : J26/K76/K77 are Yamaha numbers, no 2 Japanese semi-brands manufacturer identical labelled devices.
Thirdly : the uni-style printing on your devices, highly uncommon for the era of devices without manufacturer logo.
(Forth : the 5H-6H-7H code lots look like a million dollar sweepstake ticket)
Yamaha and NEC got into VFETs right after Sony started producing amps with the J18/K60.
Hitachi developed their Lateral MOSFETs series as an alternative, which was less costly in manufacturing.
Main reason why yours are not genuine.
Secondly : J26/K76/K77 are Yamaha numbers, no 2 Japanese semi-brands manufacturer identical labelled devices.
Thirdly : the uni-style printing on your devices, highly uncommon for the era of devices without manufacturer logo.
(Forth : the 5H-6H-7H code lots look like a million dollar sweepstake ticket)
It seems fake. 2SK77 must be much larger than 2sk76/2sj26. The package was a mammuth TO-3
Also Hitachi have made Vfets (2sk89-2sj29) if i remember.
However by this first simple mode you can check it.
With a multimeter on diode (for N devices 2sk76-77) put positive terminal on gate and negative on source or drain: you must measure a pn junction
(0,4-0,5V).
Then across Drain to Source you must measure a resistance of about 0,5-1,5 Ohm.
That is similarly to measure a signal jfets.
Francesco
Also Hitachi have made Vfets (2sk89-2sj29) if i remember.
However by this first simple mode you can check it.
With a multimeter on diode (for N devices 2sk76-77) put positive terminal on gate and negative on source or drain: you must measure a pn junction
(0,4-0,5V).
Then across Drain to Source you must measure a resistance of about 0,5-1,5 Ohm.
That is similarly to measure a signal jfets.
Francesco
Indeed, and used in amps of Hitachi's subsidiary company Lo-D.
But that was mid-70s, a couple of years before the first Lateral MOSFETs came out, with Lo-D label.
The J29/K89 are a good example of how different the Hitachi print looks
Half an inch longer than regular TO3s
Last edited:
With a multimeter on diode is 0,42v
Then across Drain to Source you must measure a resistance of about 2 Ohm
Very well. we are in the right direction.
You must measure the 0,4V pn voltage either among gate to source and among gate to drain.
About 2 ohm Resistance you must measure between D-S in either directions.
If these are in that way, pheraps they are good. (sure they not are mosfet)
To verify these devices in deep you need a circuit with: (Example is for N devices)
1 power supply of about 25-35 Vdc
1 10k Ohm 5-10 W resistor wired from Drain to positive rail
1 1k Ohm 5 W variable resistor wired from source to negative rail.
1 piece of wire from negative rail to gate.
It is better if you put device on a heatsink
Start with variable resistor to max value.
Put a voltmeter at the two ends of 10k resistor.
You would read a voltage drop on resistor.
If no, then you must diminuish slowly the value of variale resistor on the source.
Generally, the N Vfets are going in on state when the Vgs is lower than -15V but is depend on model and rank (-5V at least).
Last edited:
ckeck out also this thread:
http://www.diyaudio.com/forums/soli...aha-2sk77-nec-2d363-overview.html#post2211567
http://www.diyaudio.com/forums/soli...aha-2sk77-nec-2d363-overview.html#post2211567
IF these test like VFETs, they are most likely Sony J18/K60 with re-printed labels, and the source is somewhere in China. In a similar manner, I've seen Yamaha J20/K70 (J20/K70 were ONLY made by NEC). J26/K76 were made by Yamaha and only Yamaha and the case looks a bit different. K77 only vaguely resembles a TO-3 case, it is HUGE, about 8 times the volume (approximately twice as large in every direction) with a very thick base (the flat part that goes to the heatsink) and very heavy.
Hitach iand NEC used color print on parts of that era, black for Nch or NPN, red (NEC/Hitachi) and on occasion green (Hitachi) for Pch/PNP.
There are some genuine J26/K76 sources in China but these parts are factory rejects and about 1 i 3 tests properly on a curve tracer, but being a reject there is high risk it will fail.
Hitach iand NEC used color print on parts of that era, black for Nch or NPN, red (NEC/Hitachi) and on occasion green (Hitachi) for Pch/PNP.
There are some genuine J26/K76 sources in China but these parts are factory rejects and about 1 i 3 tests properly on a curve tracer, but being a reject there is high risk it will fail.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.