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-   -   Hifonics HFI2000D goes to protect (http://www.diyaudio.com/forums/car-audio/214683-hifonics-hfi2000d-goes-protect.html)

brandes.cm 18th June 2012 12:18 AM

Hifonics HFI2000D goes to protect
 
Amp goes directly into protect, I noticed pin 1 of TL494 reads 5.86V and pin 2 reads 2.56V. I believe this ties to +rail and uses a divider to set the voltage.

I have pulled the output driver card and measured the transistors, all read OK.

Perry Babin 18th June 2012 11:29 AM

If no one else can help, post a photo of the board.

brandes.cm 18th June 2012 12:08 PM

Photo coming later, but this amp is no different than the later Brutus stuff.

brandes.cm 18th June 2012 09:30 PM

http://img.tapatalk.com/a6fae314-9dd8-8443.jpg

http://img.tapatalk.com/a6fae314-9dff-4102.jpg

Perry Babin 18th June 2012 11:38 PM

Pin 1 can't be driven high by the positive rail if the IC isn't producing output. Are you sure that it's not being driven high by the comparator/op-amp?

brandes.cm 19th June 2012 12:13 AM

3 Attachment(s)
I find no other connection to that pin and now wonder if the TL494 is just bad. Attached is a schematic for a BX1500D, seems close.

Perry Babin 19th June 2012 12:29 AM

If the circuit is the same and the 4.7k resistor is within tolerance, the IC is defective.

Something that doesn't seem right is the 2.5v on pin 2. Pin 2 should be at 5v according to the diagram. If it's at 2.5, that would seem to indicate that there is a voltage divider that's not shown in the diagram.

Perry Babin 19th June 2012 12:32 AM

Is it possible that pins 1 and 7 of the comparator go to diodes D9 and D10 and then to pin 1 of the 494?

brandes.cm 19th June 2012 12:57 AM

I lifted pin 1 and it goes to 14.4V when measuring on the pin. I assume the IC doesn't have a pull-up resistor built in.

brandes.cm 20th June 2012 01:37 AM

Quote:

Originally Posted by Perry Babin (Post 3064409)
Is it possible that pins 1 and 7 of the comparator go to diodes D9 and D10 and then to pin 1 of the 494?

Yes that is correct.


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