The thermistors?
It’s been off for a bit.
I can power up, and check temperature with a laser thermometer?
It’s been off for a bit.
I can power up, and check temperature with a laser thermometer?
It’s pretty cold in my “work room”
Temperature on the circuit boards is about 18C. The thermistors go up to about 20.5 when left on and don’t seem to get any hotter.
The trim pots, on both channels, are going over 25C
Temperature on the circuit boards is about 18C. The thermistors go up to about 20.5 when left on and don’t seem to get any hotter.
The trim pots, on both channels, are going over 25C
I will get a fresh sheet of paper, a different pen and measure/take new notes!
Will also double check that wires are going where they should from the PS to the amp boards. Triple checked them before I powered up, but will make sure!
Thanks!
Will also double check that wires are going where they should from the PS to the amp boards. Triple checked them before I powered up, but will make sure!
Thanks!
I took lots of photos! And the connection points are very well labeled.
It was DOA, and I knew it wasn’t working.
Only powered it up, never tried it. Especially after seeing the voltages on the speaker terminals.
Part of a trade - was generously given as a “bonus”.
Figured I would look at it before I dove into the KSA 200, which is also not working.
Measured the B+ on L/R, ant both +60vdc and +73vdc, using speaker ground.
Right side 124.7vdc at the 60vdc B+, 138.4vdc at the 73vdc B+
Left side -7.17vdc at the 60vdc B+, 4.28vdc at the 73vdc B+
I should point out, that the speaker ground I’m using is the ground connector on the amp board.
In order to test voltage at Q2, I am unable to connect the wires that go to the output from the amp board. Not sure if that matters?
It was DOA, and I knew it wasn’t working.
Only powered it up, never tried it. Especially after seeing the voltages on the speaker terminals.
Part of a trade - was generously given as a “bonus”.
Figured I would look at it before I dove into the KSA 200, which is also not working.
Measured the B+ on L/R, ant both +60vdc and +73vdc, using speaker ground.
Right side 124.7vdc at the 60vdc B+, 138.4vdc at the 73vdc B+
Left side -7.17vdc at the 60vdc B+, 4.28vdc at the 73vdc B+
I should point out, that the speaker ground I’m using is the ground connector on the amp board.
In order to test voltage at Q2, I am unable to connect the wires that go to the output from the amp board. Not sure if that matters?
You got it right.
Sorry for my rambling explanation.
What I was trying to explain, is that I didn’t have the leads going from the amp boards to the speaker terminals. I was using the speaker ground point on the each of the amp boards.
I reconnected the cables that go from amp boards to the speaker terminals and measured again.
That changed things…
Using the actual speaker terminal, instead of the ground on the amp boards, the numbers are a lot more balanced…
On the right, I am getting 79.7vdc at the 60vdc B+ and 93.5vdc at the 73vdc B+
On the left, I am getting 80.7vdc at the 60vdc B+ and 89.2vdc at the 73vdc B+
And I am getting -79vdc on left and right speaker terminals (give or take .5vdc…)
Sorry for the confusion, I had no idea running the wires from the amp terminals to the posts would make that big a difference 🙁
Guess ground reference is not the same on the boards?
Sorry for my rambling explanation.
What I was trying to explain, is that I didn’t have the leads going from the amp boards to the speaker terminals. I was using the speaker ground point on the each of the amp boards.
I reconnected the cables that go from amp boards to the speaker terminals and measured again.
That changed things…
Using the actual speaker terminal, instead of the ground on the amp boards, the numbers are a lot more balanced…
On the right, I am getting 79.7vdc at the 60vdc B+ and 93.5vdc at the 73vdc B+
On the left, I am getting 80.7vdc at the 60vdc B+ and 89.2vdc at the 73vdc B+
And I am getting -79vdc on left and right speaker terminals (give or take .5vdc…)
Sorry for the confusion, I had no idea running the wires from the amp terminals to the posts would make that big a difference 🙁
Guess ground reference is not the same on the boards?
I kinda figured the voltages are high because of no load. Thank you for confirming that!
Does it matter what side of the .68R I check? The difference in the two would be the current draw, is that correct?
And I suspect I should measure each one, keeping the speaker ground as reference for this as well?
Does it matter what side of the .68R I check? The difference in the two would be the current draw, is that correct?
And I suspect I should measure each one, keeping the speaker ground as reference for this as well?
For the 0.68R connect the probes across each one. One probe at each end of the resistor.
Do not connect either probe to the speaker terminal. Like you were measuring its resistance.
But this is on the DC volts range, and powered, and you are measuring a floating DC voltage instead.
Any current in the related output FET will cause a voltage drop across the resistor.
The current is equal to the DC voltage between the ends of the resistor, divided by 0.68 ohms.
Your DVM can measure a floating DC or AC voltage because of its design and insulated case.
An oscilloscope usually cannot do this, and one of the oscilloscope probe terminals is usually connected to ground.
Do not connect either probe to the speaker terminal. Like you were measuring its resistance.
But this is on the DC volts range, and powered, and you are measuring a floating DC voltage instead.
Any current in the related output FET will cause a voltage drop across the resistor.
The current is equal to the DC voltage between the ends of the resistor, divided by 0.68 ohms.
Your DVM can measure a floating DC or AC voltage because of its design and insulated case.
An oscilloscope usually cannot do this, and one of the oscilloscope probe terminals is usually connected to ground.
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I still think that both of the TH101 switches must be off (open). See my post #30.
Or something with a similar effect, like an open circuit connection to the switches.
The amplifier output stages are both turned off, by disabling the input stage current sources.
Can you check whether there are two of the TH101 (one per channel) on the heat sink?
There should be two.
Or something with a similar effect, like an open circuit connection to the switches.
The amplifier output stages are both turned off, by disabling the input stage current sources.
Can you check whether there are two of the TH101 (one per channel) on the heat sink?
There should be two.
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It should be a small metal guy with two leads coming off it.
Kinda, a little like this one. But it could look different, depending.
https://www.amazon.com/Temperature-Control-Thermostat-Thermal-Normally/dp/B07XFZLP2H/ref=asc_df_B07XFZLP2H/
Kinda, a little like this one. But it could look different, depending.
https://www.amazon.com/Temperature-Control-Thermostat-Thermal-Normally/dp/B07XFZLP2H/ref=asc_df_B07XFZLP2H/
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