please answer if it's a dps error and should I connect R30 to R31. According to the diagram, they are connected. Thank you for answer.
Certainly,
the schematic is relevant, PCB layout must be according to the schematic. Recheck the entire PCB for additional errors, if there are any more....
the schematic is relevant, PCB layout must be according to the schematic. Recheck the entire PCB for additional errors, if there are any more....
I checked and everything should be fine. I corrected the error by connecting the resistor according to the diagram. I'm afraid I'll ruin something. I turn on the light bulb..
I would say that it would be explained that they were not properly tensioned on Bd139. Possible?
Yes.
PowerON with light bulb (60W) on the primary.
But firstly adjust bias trimmpot P1 at max value 1K, that you will start with minimum OPS bias, then gradually increase it...
PowerON with light bulb (60W) on the primary.
But firstly adjust bias trimmpot P1 at max value 1K, that you will start with minimum OPS bias, then gradually increase it...
That's how it worked. The setting is smooth and fine. I still ask, will 23mV on the emitter resistors be OK?
Yes
I write that earlier:
Then gradually increase I_bias so the voltage drop readings on R34 or R35 (0R33) are approx. 20...25mV/per 0R33
That is approx 23mV/0R33=>70mA BIAS OPS
Did you change R33 220R for 100R???
, with 100R you would have more Aclass Drivers bias (approx 12...15mA) => so you lower THD with more Drivers bias !
Congrat with your working amp!!!
I write that earlier:
Then gradually increase I_bias so the voltage drop readings on R34 or R35 (0R33) are approx. 20...25mV/per 0R33
That is approx 23mV/0R33=>70mA BIAS OPS
Did you change R33 220R for 100R???
, with 100R you would have more Aclass Drivers bias (approx 12...15mA) => so you lower THD with more Drivers bias !
Congrat with your working amp!!!
Thank you once again for your support Mr. Dragan100. You said it absolutely correctly that there is something wrong around R30, R31. I used 0R22 resistors for the emitter, the 23mV will be too much, around 100mA, I will reduce it to 13-15mV, I will get something around 60mA. I did not change the 220R resistors. Will it be reflected in the sound?
It would be easiest to put 220R in parallel, I would get 110R. I will try it tomorrow and I am very curious. I should also get the new NJW0302/ NJW0281, I want to try them, they should have better ones.
Try paralleling 220R//220R for R33
100mA for bias is not too much, higher OPS bias => lower THD,
but depends on your HeatSinks size if they can handle with no too much essagerated/higher temperature.
100mA for bias is not too much, higher OPS bias => lower THD,
but depends on your HeatSinks size if they can handle with no too much essagerated/higher temperature.
I'll add that one tomorrow
R33/ 220R. I'll be testing and debugging + so I'll still try the NJW0302/ NJW0281 ones. I am very curious. I will share the result.
R33/ 220R. I'll be testing and debugging + so I'll still try the NJW0302/ NJW0281 ones. I am very curious. I will share the result.
Hello everyone here on the forum. To sum it up. I adjusted the resistor R33 to about 110R, replaced the transistors with NJW0302/ NJW0281 (Mouser supplier), set the bias to 23mV. I'm enjoying it now, beautiful full sound! First of all, I want to thank Mr. Dragan100 for his support, for providing a lot of information on how to do what correctly.
I read with joy that you have managed to start the amplifier with additional small changes,
now your drivers are working with a slightly higher local Bias 10 ... 13mA => 1,3..1,4V/110R,
you set up OPS Bias to 23mV/0R22 => This is approximately 100mA
Did you control now the temperature of Main HeatSinks?
60°C is approximately that you can last with your fingers holding HeatSink approx for 5sec!
Or you can measure with ThermoCouple exactly temperature! DMM+ThermoCouple
Did you measure on resistors R26/28 100R Voltage drop => your VAS bias with 18V IPS Zeners?
now your drivers are working with a slightly higher local Bias 10 ... 13mA => 1,3..1,4V/110R,
you set up OPS Bias to 23mV/0R22 => This is approximately 100mA
Did you control now the temperature of Main HeatSinks?
60°C is approximately that you can last with your fingers holding HeatSink approx for 5sec!
Or you can measure with ThermoCouple exactly temperature! DMM+ThermoCouple
Did you measure on resistors R26/28 100R Voltage drop => your VAS bias with 18V IPS Zeners?
Everything works as you write. I checked the zeners and they are 15V, I measure 16.2V on them at a supply voltage of 43.7VDC, so everything is probably fine, some tolerance of the components. I will gradually check the temperature and make measurements or adjustments.
You rapport +/-18,2VDC on zeners in last schematics voltage measurements writing!
with +/-17,6VDC IPS Caskode polarization, {18,2 - Vbe} = 17,6V (Vbe = 0,6..0,8V)
and 1,33VDC voltage drop on resistors R26/28 100R. so this is 13,3mA VAS BIAS,
are Q10 and Q6 HOT??? ...more then 60°C+++
Uce*Ibias = cca 40...42VDC*13,3mA=> 0,5..0,6W thermal dissipation/per VAS TO92 BJT,
and they must be HOT BF420/421 in TO92 case, they definitely need little heatsinks,
or you use some compatible VAS BJTs there? ...TO128 case?
with +/-17,6VDC IPS Caskode polarization, {18,2 - Vbe} = 17,6V (Vbe = 0,6..0,8V)
and 1,33VDC voltage drop on resistors R26/28 100R. so this is 13,3mA VAS BIAS,
are Q10 and Q6 HOT??? ...more then 60°C+++
Uce*Ibias = cca 40...42VDC*13,3mA=> 0,5..0,6W thermal dissipation/per VAS TO92 BJT,
and they must be HOT BF420/421 in TO92 case, they definitely need little heatsinks,
or you use some compatible VAS BJTs there? ...TO128 case?
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Hi Dragan100, I'm sorry I'm writing now. I did a measurement after the jumper between the resistors, it behaved badly in general and after that everything calmed down. The measurements I wrote to you were before the dps repair. Now it seems to me that it behaves really correctly. I use BF420/ 421, I changed the resistor from 15K to 18K. The sound is delicious, beautiful, everything is quiet, nothing disturbs the sound is full of detail. I will have more time at the weekend.
Hi Alex,
If possible Please give me the Gerber files for the Sanken layout (SR200 V2.2)
