Powerbass XTA500D

[S Merlington]

Do theese voltages look right on the pads for the audio driverboard ??

The audio driverboard is out of the amp right now ..

Amp powers up and relays enguage but has no outout..

Heres the voltages i have on the pads for the auio driverboard do they appear to be right ??

Pin 1:0.00
Pin 2:-131.5
Pin 3:-119.6
Pin 4:-130.9
Pin 5:1.46
Pin 6:1.46
Pin 7:-130.6
Pin 8:1.46
Pin 9:1.46
Pin 10:--131.3
Pin 11:-131.2
Pin 12:0
Pin 13:1.63
Pin 14:16.58
Pin 15:1.45
Pin 16:1.45
Pin 17:1.45
Pin 18:-3.47
Pin 19:0.00
Pin 20:0.00
Pin 21:-131.3
Pin 22:-131.3
Pin 23:-119.3
Pin 24:-130.6
Pin 25:1.45
Pin 26:1.45
Pin 27:-130.6
Pin 28:1.45
Pin 29:1.45
Pin 30:-131.2
Pin 31:-131.2
Pin 32: 0.00

 

[Perry Babin]

If no one can help, post a photo of the driver board. I've can't remember ever seeing a driver board with more than 29 pins.

 

[S Merlington]

Ok i must be tired Who ever had this amp before had sockects solderd to the board so you could plug the driverboard in and had to many spots..

This is the 29 pin driverboard..

After removing the sockets heres what i get on the Pads for the Audio driverboard..

Pin 1:-130.1
Pin 2:-118.6
Pin 3:-129.8
Pin 4:1.44
Pin 5:1.44
Pin 6:-129.3
Pin 7:1.45
Pin 8:1.45
Pin 9:-129.6
Pin 10:-129.6
Pin 11:-129.6
Pin 12:1.58
Pin 13:16.57
Pin 14:1.43
Pin 15:1.43
Pin 16:1.43
Pin 17:-3.49
Pin 18:0.00
Pin 19:-129.3
Pin 20:-129.0
Pin 21:-117.0
Pin 22:-128.2
Pin 23:1.45
Pin 24:1.45
Pin 25:-128.3
Pin 26:1.45
Pin 27:1.45
Pin 28:-128.8
Pin 29:-128.9

 

[Perry Babin]

At least two of the regulated voltages look off. Check all regulators with the black probe on the ground terminal for the regulator being checked. Confirm that the output voltage is what it's supposed to be.

 

[S Merlington]

7905 black probe on Leg 1 red probe on leg 3:-4.92

7805 Black probe on Leg 2 red probe leg 3:5.01

7915 black probe on Leg 1 red probe leg 3:-14.70

7815 Black probe leg 2 red Leg 3:15.13

Theres 2 7812's n this amp

first 1

7812 Black probe Leg 2 red probe leg 3:12.02

2nd 7812 12.01

 

[S Merlington]

Ok all regulators have the correct voltages on them..

If i use the secondary center tap as a ground reference i get the following on the pads for the driverboard..

Pin 1:-132.5
Pin 2:-120.4
Pin 3:-131.7
Pin 4:0.00
Pin 5:0.00
Pin 6:-131.5
Pin 7:0.00
Pin 8:0.00
Pin 9:-132.2
Pin 10:-132.1
Pin 11:-132.1
Pin 12:0.38
Pin 13:15.10
Pin 14:4.96
Pin 15:-0.04
Pin 16:-0.04
Pin 17:-4.97
Pin 18:0.02
Pin 19:-132.0
Pin 20:-132.1
Pin 21:-120.0
Pin 22:-131.3
Pin 23:0.00
Pin 24:0.00
Pin 25:-131.3
Pin 26:0.00
Pin 27:0.00
Pin 28:-131.9
Pin 29:-132.0

Do theese voltages look right or do i have something missing

 

[S Merlington]

See post above...

Also i noticed QP1 in this amp is an A1266

Do you know what QP2 is suppose to be??

In QP2's spot right now there is a D1302 that doesnt seem right to me since there are already 2 D1302's in this amp (Q19,Q62)

 

[Perry Babin]

I don't know what's supposed to be in the location QP2. Maybe powerbass will tell you what it's supposed to be if you email them.

Is this a DWM3640 driver board? If so, I don't see anything that's significantly different from what I'd expect.

 

[S Merlington]

Ok i rebuilt the Audio driverboard Replaced all of the IC's and all surface mount transistors..

Replaced all of the outputs..

Amp powers up relays engage amp has no output..

I checked the slave master switch its set to master..

I have audio on Pin 15 of the driverboard..

I dont see any rail to rail oscillation on any of the outputs..

Any ideas what to check since this amp has no output ?

 

[S Merlington]

When i was testing voltages i dropped my meter lead on the middle leg of the output and i didnt see what else it touched but there was a spark at the output and now the amp is stuck in protection mode..

I pulled the audiodriverboard and tesetd the outputs but the amp is still stuck in protction..

Heres the voltages on the 494

Pin 1:13.22
Pin 2:2.55
Pin 3:4.76
Pin 4:4.14
Pin 5:1.54
Pin 6:3.66
Pin 7:0
Pin 8:13.88
Pin 9:0
Pin 10:0
Pin 11:13.88
Pin 12:13.88
Pin 13:7.41
Pin 14:7.41
Pin 15:7.41
Pin 16:0

Heres what i have on the LM293

Pin 1:0.18
Pin 2:7.55
Pin 3:7.43
Pin 4:0
Pin 5:1.52
Pin 6:6.01
Pin 7:0.18
Pin 8:13.84

Any ideas where to check??

 

[Perry Babin]

Re-check your numbers for pin 1 of the 494 and pins 1 and 7 of the 393. The 293 drives pin 1 in most cases but the voltage is low which couldn't drive pin 1 of the 494 to 13v.

 

[S Merlington]

TL494

Pin 1:13.97

LM293

Pin 1:13.56
Pin 7:0.18

Thats if im using the ground termianl as referemce

If i use the secondary center tap as reference All voltages ae the same besides PIN 7 of the 293 and that voltage is -1.93 if i use the secondary center tap

 

[Perry Babin]

This is on the primary side of the power supply so you use the amp's main (primary) ground.

Post the DC voltage on all pins of the 293 since the voltage on the output pin has changed.

 

[S Merlington]

Pin 1:13.56
Pin 2:7.56
Pin 3:7.44
Pin 4:0
Pin 5:1.52
Pin 6:6.10
Pin 7:0.18
Pin 8:13.84

 

[Perry Babin]

It appears that the 494 has failed. The 5v output is at 7+v.

 

[S Merlington]

Should i switch the LM293 also?

 

[Perry Babin]

The voltage readings aren't conclusive. If you have to remove the driver board to do it and have one in stock, replace it.

 

[S Merlington]

The LM393 is basically the same correct?

 

[Perry Babin]

Yes.

 

[S Merlington]

Ok switched out the 494 and the 293 amp is still stuck in protection mode

Heres the voltages i get now

Pin 1:13.23
Pin 2:2.53
Pin 3:4.64
Pin 4:4.03
Pin 5:1.43
Pin 6:3.63
Pin 7:0
Pin 8:13.87
Pin 9:0
Pin 10:0
Pin 11:13.87
Pin 12:13.87
Pin 13:4.95
Pin 14:4.95
Pin 15:4.95

LM293
Pin 1:0.19
Pin 2:7.52
Pin 3:4.95
Pin 4:0
Pin 5:1.01
Pin 6:4.00
Pin 7:0.19
Pin 8:13.87

I tripple check the voltages on pin 1 of the 293 and PIN 1 of the 494 and thats what i get