On the LM393 I'm seeing
Pin
1- 0v
2- 5.15
3- 0v
4- Gnd
5- 0v
6- 0v
7- 0v
8- 11.3v
I see some should be inputs (A&B) and outputs A&B......
Does this look right?
Pin
1- 0v
2- 5.15
3- 0v
4- Gnd
5- 0v
6- 0v
7- 0v
8- 11.3v
I see some should be inputs (A&B) and outputs A&B......
Does this look right?
There isn't much to see/know from this. 4 and 8 are OK. The values for 1, 2 and 3 are OK. 5, 6 and 7? Unused? I wouldn't expect all 3 to be 0.0v.
I'm not sure why you're checking this IC. These are typically used in the protection circuit.
I'm not sure why you're checking this IC. These are typically used in the protection circuit.
I'm just checking all components perry. I've been over every single sot23 and resistors and diodes I can't find a problem. I'm yet to remove the output driver cards yet.
I haven't yet tested all capacitors as that's very tedious
I haven't yet tested all capacitors as that's very tedious
With the PS pulsing on and off, twist/push/pull the power transformers to see if anything changes.
already done that there was no change.
Owner said he saw a over voltage light then he powered it off then back on only to produce no audio.
After removing the shorted sot23 PNP I now get audio out of rear channels however none out of front. Also if I refit the PNP I get extreme current draw (13A) then just on/off attemps at building power supply drive
Owner said he saw a over voltage light then he powered it off then back on only to produce no audio.
After removing the shorted sot23 PNP I now get audio out of rear channels however none out of front. Also if I refit the PNP I get extreme current draw (13A) then just on/off attemps at building power supply drive
Do you see any pulsing of DC on the bridging terminals of any channels when you have Q713 in the circuit? Ground the scope to one of the non-bridging speaker terminals when checking.
Yes I am seeing DC bump. It will first bump up to I'm not sure its too fast too see. Then will again bump up with the motion of the screaming transformers which pulsate
And no outputs heat up with the pulsing?
Watch the PS FETs so they don't get too hot.
Is the DC on only one channel? 2 channels?
In some of these Orion amps, there is a 10 ohm resistor on the output of each voltage regulator (could be IC regulator or discrete). Confirm that all are within tolerance.
Watch the PS FETs so they don't get too hot.
Is the DC on only one channel? 2 channels?
In some of these Orion amps, there is a 10 ohm resistor on the output of each voltage regulator (could be IC regulator or discrete). Confirm that all are within tolerance.
Power supply does get hot. Not all of them though.
I have felt the outputs get hot when running a subwoofer. If I'm not mistaken (and please correct me if I'm wrong) there is a thing called thermal runaway. What I'd notice when running a subwoofer the outputs would heat up to a certain degree then u would see the amperage start to rapidly increase and the outputs would just get super super hot. I never let it get too bad as I'd shut it down. It's My understanding that this is normal and called thermal runaway and is a result of no heat sink.
No outputs get hot unless u load up the channel
I'll check all the resistors near the volatge regulators. Do you mean the LMs that clamp to the heat sink?
I have felt the outputs get hot when running a subwoofer. If I'm not mistaken (and please correct me if I'm wrong) there is a thing called thermal runaway. What I'd notice when running a subwoofer the outputs would heat up to a certain degree then u would see the amperage start to rapidly increase and the outputs would just get super super hot. I never let it get too bad as I'd shut it down. It's My understanding that this is normal and called thermal runaway and is a result of no heat sink.
No outputs get hot unless u load up the channel
I'll check all the resistors near the volatge regulators. Do you mean the LMs that clamp to the heat sink?
For most all class AB amplifiers, there is a bias compensation transistor that's thermally mated to the outputs via the heatsink. The bias transistor counteracts the tendency for the outputs to pass more current when hot (when at their threshold). When off of the heatsink, the bias transistor can't track (thermally) the outputs so it loses its ability to compensate and the outputs avalanche (runaway).
You stated that you now see ±rail voltage. Why weren't you seeing it earlier? What changed?
You stated that you now see ±rail voltage. Why weren't you seeing it earlier? What changed?
I didn't originally read off the correct location. I do know better. Just this amp is starting to send me a bit crazy.
You asked about biasing earlier. It's true that you have to reset biasing after a repair where you replace transistors but it's also possible that someone went into the amp and tried to adjust them to get the amp to work. It's also possible for the bias to drift over time. If none of your outputs are heating up, I doubt the bias is the problem. Just answering the question.
Does this amp have isolated power supplies? Resistance between secondary center-taps?
You stated that 'not all' of the PS FETs heat up. How is the heating gouped? By transformer? By one bank on one transformer? Or random heating?
Is the rail voltage different with and without Q713?
Does this amp have isolated power supplies? Resistance between secondary center-taps?
You stated that 'not all' of the PS FETs heat up. How is the heating gouped? By transformer? By one bank on one transformer? Or random heating?
Is the rail voltage different with and without Q713?
Rail remains the same regardless of PNP in or out.
With Q713 fitted and it initially draws upwards of 13A. Once it settles down and just pulsates only these 2 groups on each side are getting warm. (Circled in photo) others remain stone cold.
They do get very hot on the initial start up when it's drawing 13A.
I'll get that resistance reading for you once I google what the centre tap is on the secondary. Just to be sure I give you an accurate reading
With Q713 fitted and it initially draws upwards of 13A. Once it settles down and just pulsates only these 2 groups on each side are getting warm. (Circled in photo) others remain stone cold.
They do get very hot on the initial start up when it's drawing 13A.
I'll get that resistance reading for you once I google what the centre tap is on the secondary. Just to be sure I give you an accurate reading
Do the signals on the gate legs of all of the PS FETs look the same? Q713 in or out of the circuit?
By pulsating, do you mean that the pulse train out of the driver IC repeatedly completely shuts down?
Do any other terminals on the driver IC pulse in relation with the shutdown?
By pulsating, do you mean that the pulse train out of the driver IC repeatedly completely shuts down?
Do any other terminals on the driver IC pulse in relation with the shutdown?
Without q713 in circut all the power supply mosfets get the exact same signal on all legs.
With q713 in circut it's almost impossible to see as it just winds up and down probably once per second so its basicly impossible to see.(looking for signal on the PS fets)
Yes every single thing in regards to plus or minus volatge moves with the noise of the transformers.
If u leave it with no power for any decent period of time, then when you go to power it up (q713 in circut) it will not draw excessive current for about 25 seconds (draws about 2A) then goes up to 13A then the transformer noise and palse will be more rapid and it will then draw less current. (Doen to 0.10-1.3A)
I just got word that this amp did indeed see over 16V. Not just the light.
Would it be wise to replace the UC3526? I don't have any on hand but can order it I'd assume.
Just seems as soon as q713 goes in it causes havoc and q713 is connected to pin 17 of the UC. (Thrugh a capacitor)
With q713 in circut it's almost impossible to see as it just winds up and down probably once per second so its basicly impossible to see.(looking for signal on the PS fets)
Yes every single thing in regards to plus or minus volatge moves with the noise of the transformers.
If u leave it with no power for any decent period of time, then when you go to power it up (q713 in circut) it will not draw excessive current for about 25 seconds (draws about 2A) then goes up to 13A then the transformer noise and palse will be more rapid and it will then draw less current. (Doen to 0.10-1.3A)
I just got word that this amp did indeed see over 16V. Not just the light.
Would it be wise to replace the UC3526? I don't have any on hand but can order it I'd assume.
Just seems as soon as q713 goes in it causes havoc and q713 is connected to pin 17 of the UC. (Thrugh a capacitor)
I don't like blindly replacing parts but have so little information on this amp that that may be the solution, sooner or later.
If you limit the current can you see the drive waveform with Q713 in the circuit?
If you limit the current can you see the drive waveform with Q713 in the circuit?
Yes... if I limit it to 1.5A I get this on all power supply fets
First pic is gate drive
Second is back of mosfet(drain)
Q713 is still in circut
First pic is gate drive
Second is back of mosfet(drain)
Q713 is still in circut
Pretty much. I say pretty much because I don't have a fancy power supply. It's just a power supply I built myself. It is however accurate u just can't dial it in to the Mah.
But once it sees 2A is throws a fit.
But once it sees 2A is throws a fit.