Do the voltages on the 494 change significantly if you set the supply to 12v, 13v and 14v?
No need to post all of the voltages. This is simply to see if the amp is sensitive to the input voltage.
No need to post all of the voltages. This is simply to see if the amp is sensitive to the input voltage.
The following may defeat part of the protection circuit so be careful.
Solder a bridge between the collector and emitter of Q615. Does the amp power up normally?
If so, does it produce clean audio?
Clamp all FETs to prevent them from overheating if there is a problem.
Solder a bridge between the collector and emitter of Q615. Does the amp power up normally?
If so, does it produce clean audio?
Clamp all FETs to prevent them from overheating if there is a problem.
Are the components in this amp epoxied to the board?
I'd like you to remove R636(?), 820 ohm but I don't want you to destroy it.
I'd like you to remove R636(?), 820 ohm but I don't want you to destroy it.
I do not have audio, there is only rail voltage +28 and -28 in some cases in 2 banks there are only 25v
Are you sure that you're looking at the terminals of the output transistors that are connected to the rails?
There is only one transformer and one set of rectifiers so all rail voltages should be identical.
Do you see any DC across the speaker terminals of any channel?
There is only one transformer and one set of rectifiers so all rail voltages should be identical.
Do you see any DC across the speaker terminals of any channel?
In general, if the term 'rail voltage' is used, it's referring to the main rails that are produces to supply power to the output transistors.
For other supplies, if the term 'rail' is used it's specific as in ±15v rails or 5v rail.
For other supplies, if the term 'rail' is used it's specific as in ±15v rails or 5v rail.
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