I need to know the equivalent power transistor for a marked H101A placed in the Hill Audio DX3000.
Thanks.
Thanks.
Last edited:
In 1992 Hill Audio went into administration ,new designs were introduced by the buyer of the company .
Looking at the schematic this professional company didn't want anybody ripping off their designs so the output BJT,s aren't marked.
With that amount of power output "guesswork " can cost a lot .
Looking at the schematic this professional company didn't want anybody ripping off their designs so the output BJT,s aren't marked.
With that amount of power output "guesswork " can cost a lot .
In the LCSeries the MJ15003 or 15024 is used.
The supply voltage is +/- 80V? Or higher?
Do you have a schematic. Otherwise pm me. It's a bit large (20M)
The supply voltage is +/- 80V? Or higher?
Do you have a schematic. Otherwise pm me. It's a bit large (20M)
Thanks. I have dx 3000 schematic and material list. I have fixed the other channel.
I was thinking about those transistor Mj15003 (250w, 140V Vce, 20A Ic), but have hi gain (Hfe: 60-150) The H101A of the Dx3000 have the gain around 15-37. Also I was thinking in 2N3773 with similar gain (15-60) but less power (150w) than Mj15003 similar Vce( 140) less Ic (16A). The problem is that I have tested the 20 transistor and seems are correct and all have a similar gain. But there is a high frequency oscilation when powered with charge that make me crazy.
I was thinking about those transistor Mj15003 (250w, 140V Vce, 20A Ic), but have hi gain (Hfe: 60-150) The H101A of the Dx3000 have the gain around 15-37. Also I was thinking in 2N3773 with similar gain (15-60) but less power (150w) than Mj15003 similar Vce( 140) less Ic (16A). The problem is that I have tested the 20 transistor and seems are correct and all have a similar gain. But there is a high frequency oscilation when powered with charge that make me crazy.
i'd be looking at capacitors real closely rather then worry about transistor spec's...it is a design that is quite old and time is not friendly to capacitors...
a cap can be of correct value but still have it's ESR be off.
what else do you think is the cause of the oscillation?
what else do you think is the cause of the oscillation?
I don't think is a cap because are in negative feedback circuit but everything is possible. Maybe is one final transistor with a strange hi gain in hi frecuency. I will disconnect all from the rail and connect pair by pair. It will takes time (20 u) but is a scientific method (probe-error).
well it been a long time since i've seen a DX3000 let alone worked on one but as i recall (wish i had the schematic in front of me) there's rail protection diodes and if the unit ever had an output failure they can go faulty causing the supply to appear asymmetrical to the output stage that will ring,no?
That wouldn't necessarily cause HF oscillation Turk182 unless different active components were fitted while making no changes to either the compensation or the components around the output or driver stage .
The feedback isn't straight forward and the circuit certainly has a lot of small value local compensation capacitors.
What you should be doing is checking the outputs from the two -IC2/102 TDA2030 chips on an oscilloscope while inputting an audio signal , if okay to there then its through the transformers feeding the output devices bases .
The feedback isn't straight forward and the circuit certainly has a lot of small value local compensation capacitors.
What you should be doing is checking the outputs from the two -IC2/102 TDA2030 chips on an oscilloscope while inputting an audio signal , if okay to there then its through the transformers feeding the output devices bases .
well i hope Tarzan wouldn't mind PM'ing me the schematic as that's not what i remember of the DX...or i could be recalling the three channel TX series amps..???
oh wait found one and yes me old memory is failing me...and just looking briefly it appears it's a foldover limiting scheme...yikes!!
OK then, schematic problem solved.
If my old memory is correct, I repaired one in the 90's.
But I do not have the records of the repairs anymore.
I'm 80% sure I used the MJ15003.
If my old memory is correct, I repaired one in the 90's.
But I do not have the records of the repairs anymore.
I'm 80% sure I used the MJ15003.
I can't tell you the equivalent but I have ten brand new ones that I am planning on selling on a well know auction site unless someone makes me an offer I can refuse! They are a set of ten in a "Millbank" box complete with heat sink compound. We never used them to repair an amp. We used Hill Audio but I guess Millbank were a distributor.