same effect no drive.
tl494c voltage.
1.) 1.130
2.) 4.206
3.) .077
4.) 2.685
5.) 1.057
6.) 3.599
7.) .001
8.) 4.914
9.) 000
10.) 000
11.) 4.974
12.) 13.36
13.) 4.914
14.) 4.914
15.) 4.914
16.) 4.147
tl494c voltage.
1.) 1.130
2.) 4.206
3.) .077
4.) 2.685
5.) 1.057
6.) 3.599
7.) .001
8.) 4.914
9.) 000
10.) 000
11.) 4.974
12.) 13.36
13.) 4.914
14.) 4.914
15.) 4.914
16.) 4.147
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Pins 5 & 6 of IC2 and IC8-18021 are connected to Pins 9 & 10 of IC1-TL494. One of the drivers may have failed. Trace the connection from the header pins to IC2 & 8. I would point to the pins, but don't recall which ones are connected. They will be one or two pins from the left.
Once you find the pins, remove the solder so that the drive pins are no longer connected and check the TL494 for drive.
Once you find the pins, remove the solder so that the drive pins are no longer connected and check the TL494 for drive.
Attachments
Check Q3-2N7002(remote) and Q4-BC817(+5v Ref). Both are tied to The IC1-TL494 Pin 4 along with D23-DAS-40-6(output lines of IC2 & IC8). If either one fails I believe it will shut down the IC1's drive.
Q1 is burnt in the middle badly, (bc817) possibly?
zd1 is shorted.
so there is no voltage getting to Q1 now.
zd1 is shorted.
so there is no voltage getting to Q1 now.
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Q1 & Q4-C817, Q2-BCP53, Q3-2N7002 and ZD1-5.1v zener.
Q1,Q2,Q3 and ZD1 are part of the Turn on circuit. Q4 controls the soft start for the TL494 through Pin 4 DTC.
Now that you have drive does the amp have rails and output?
Q1,Q2,Q3 and ZD1 are part of the Turn on circuit. Q4 controls the soft start for the TL494 through Pin 4 DTC.
Now that you have drive does the amp have rails and output?