Fitting pairs
Yes: Please read post 15 carefully.
But be aware that if you fit one fauly transistor with one good one, you'll almost certainly end up with 2 dead ones
On checking transistors for short circuit:
I presume these are a plastic flat package of some kind.
If the transistor is going to blow the fuse, you should be able to measure a short circuit between the centre pin and one of the outer pins.
Yes: Please read post 15 carefully.
But be aware that if you fit one fauly transistor with one good one, you'll almost certainly end up with 2 dead ones
On checking transistors for short circuit:
I presume these are a plastic flat package of some kind.
If the transistor is going to blow the fuse, you should be able to measure a short circuit between the centre pin and one of the outer pins.
Hi,
I'd be carefully checking the caps on the gates of the 2sk mosfets too (I think they are c8, c9, c10, bit hard to read). Not sure what they are for, but if they are faulty then they could be turnining on your 2sk's.
Also it looks like the schemtaic shows a voltage that should be present before the resistors on the gates. Check that that voltage is what it shows on the schematic for both the 2SKs and 2SJ's. I think that this voltage should be the same regardless of whether the mosfets are installed or not as the gates have a very high impeadance.
John said to replace the drivers, just in case you didn't pick up on it the driver transistors (are I think) the MJE something or others who's collectors are connected to the gate resistors (where I said to check the voltage). These are likely blown, so you should desolder these as well, and either replace them or at least check them with your multimeter if it has a transistor checker. Correct me if I'm wrong on this John!!!!
Tony.
PS thanks for joining in John
I'd be carefully checking the caps on the gates of the 2sk mosfets too (I think they are c8, c9, c10, bit hard to read). Not sure what they are for, but if they are faulty then they could be turnining on your 2sk's.
Also it looks like the schemtaic shows a voltage that should be present before the resistors on the gates. Check that that voltage is what it shows on the schematic for both the 2SKs and 2SJ's. I think that this voltage should be the same regardless of whether the mosfets are installed or not as the gates have a very high impeadance.
John said to replace the drivers, just in case you didn't pick up on it the driver transistors (are I think) the MJE something or others who's collectors are connected to the gate resistors (where I said to check the voltage). These are likely blown, so you should desolder these as well, and either replace them or at least check them with your multimeter if it has a transistor checker. Correct me if I'm wrong on this John!!!!
Tony.
PS thanks for joining in John
The caps you speak of seem to be ok but I replaced them anyway. I have already replaced the MJE340s and 350s.
I wondered down to Jaycar this morning and picked up and new 2SK, installed it and....YAY!. It powers on.
But then, I had no sound.
I have just taken a closer look at the schematic and realised it shows you exactly what voltage it is in many places.
How easy does that make it
I wondered down to Jaycar this morning and picked up and new 2SK, installed it and....YAY!. It powers on.
But then,
I had no sound.I have just taken a closer look at the schematic and realised it shows you exactly what voltage it is in many places.
How easy does that make itWell that didn't take long. I started checking certain points for voltage and nothing was showing. So I checked my meter (the battery is going flat) on the mains power - 243VAC. O.K. thats right. Then I tried to measure the volts across the caps in the power supply - nothing!
One of the leads fell of the bridge. I have connected it and now everything seems to test fine.
In the end all that was faulty was that one 2SK1058.
Thank you all for your help. On to my next project :- a stereo DIGI 125.
One of the leads fell of the bridge. I have connected it and now everything seems to test fine.
In the end all that was faulty was that one 2SK1058.
Thank you all for your help. On to my next project :- a stereo DIGI 125.
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