two amps, two issues

[fossilfool]

So far I have successfully completed the AMP3 kit and it works great. Thank you!

But I have tried building two AMP1 kits and neither is working yet.

If you could help me I would really appreciate it.

I tested my 5V source and it works perfectly. My 5V souce is a 7805 chip connected to a 12 volt power source.

My main power source is two 32V lithium battery packs.

AMP1 #1:

When I connect all the connections and mute the amp, nothing happens. When I unmute the amp, my 5v 7805 regulator chip gets very hot. The current through the 5v is about .5 amps. This amp doesn't produce audio. HMUTE is HIGH. The TA2022 is not hot.

I may have damaged this amp when I initially connected the negative rail in reverse. This blew my fuse instantly, but perhaps it blew the chip too?

AMP1 #2:
When I connected all the connections and muted the amp, nothing happened. Then I connected the speakers and unmuted the amp. I heard a small thump in the speakers. I pressed play on my iPod and turned the volume low. It played music very low for about 20 seconds then stopped. The TA2022 chip was very hot but not smoking or exploded. I added a heat sink and tried again.

This time, I connect every and turn to mute. The AMP1 makes a whistling sound and gets hot. When speakers are not connected, there is no whistling sound and the chip doesn't get hot. HMUTE is HIGH.

When I unmute the amp and turn on the source, the speakers make music, but it is very low volume. Then the TA2022 gets hot. I switch off the main 30v rails and leave the 5v source on. The chip still produces audio

Other questions:

The instructions mention an LED, but I can't see where this is mounted.

Am I supposed to do any shared grounding of my input, 5v, or power source? Or does the AMP1 board handle all of that?

I would really appreciate your help. Thanks,

Paul Freedman

[JohnnyNorre]

Hi,

I've not built an AMP1, but the "brother" AMP5. So I have a few observations for you:

AMP1 #1: The current at the 5V supply us much too high - it should be 45-60 mA (0.045A-0.060A). You should check that you don't have any shortcuts in the 5V rail - without an power supply attached, try measuring the resistance from +5V to GND on the AMP1 board - if it shows 0 ohm or close to 0 ohm then look for a short cut. If this doesn't help, then there a good chance that the TA-2022 has blown due to the reversed negative voltage :-(

AMP1 #2: First of all, check the speakers on another amplifier, to make sure these works. The TA-2022 should not get hot at all, when playing at moderate levels (35-40 degress max.) - even without a heatsink. Only at loud levels will the temperature raise, but I've yet to experience above 50 degress. You should carefully check the voltages at the AMP1 board itself: At pin 23 and 26 on TA-2022 there should be 2.5V. At pin 2 there should be 21-22V [VNN-VN10 = -32V-(-10)]. It could be, that the adjustment of the trimmer pots are out of range - this will make the amplifier go into mute, because the offset on the outputs are wrong. Try setting the trimmers to half, then 1/4 then 3/4 to see if this corrects the problem. Regarding the LED, this will help determine if the amplifer goes into mute mode. The LED can be connected to HMUTE (pin 32 on TA2022) through a 2.7K-3.3K resistor. When the LED is lit, the amplifier is muted and when unlit the amp. is unmuted. Finally, regarding ground, the 5V supply should be connected to "5V" and "AGND" on the AMP1, while two battery packs should be connected so the +32V from battery #1 goes to V+ (on the 7 pin connector), 0V from battery 1 connected to 32V on battery 2 and connected to Pgnd and finally 0V on battery 2 goes to V- on the AMP1.

Try measuring the voltages above and post them here, then it might be possible to get closer to what could be wrong...

Johnny Norre