ads power plate 120 repair

elchino10

Member
2010-12-23 7:14 pm
Hello group,
I have an ADS power plate 120 with turn on problems. When turned on the power supply just has like a one second pulse, like burst or spike and the goes to zero volts, voltage does not go to high either. Not sure if the amplifier is in protection or power supply itself is bad. looks like it is a self oscillating power supply. any help greatly appreciated.
 
Does this amp use a odd ball 8 pin IC in the power supply like many other vintage ADS amps did? If so your likely going to have to replace that IC to get the supply to work properly again. It was the only failure other then power devices I ever saw on these old monsters.
Really odd control IC as I recall and it might be tough to locate nowadays, even I have not seen any in over a decade now.

Also please check the pin outs for the amp IC modules I think you might find protection inhibit outputs off those chips feeding back to the supply so just taking them out wont allow the supply to run either as I recall.

None of these older ADS amps had very sophisticated power supplies but they did protect very well and I remember these did not burn up speakers on failure, so they did prevent DC output to drivers pretty good. Hope some of this helps...:)
 
The attached diagram is from a PS5. Is the power supply similar?
 

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If you're referring to the UPC1237, the following are notes I started on but didn't confirm 100%. Someone should correct them if there is an error. If you find something different in your amp, post what you find.

Pin 1: overload detect (must be below 0.7v -> generally at 0v)
Pin 2: DC offset detect (must be between +0.62 and -0.17 -> generally at 0v)
Pin 3: reset mode (grounded to require that power be cycled to re-engage relay)
Pin 4: AC detect (must be above 0.74v)
Pin 5: ground (measure other voltage with reference to this pin)
Pin 6: ground for relay (near ground to engage relay, near supply voltage for relay during mute/protect)
Pin 7: mute delay (must be above 2.06v)
Pin 8: supply (generally between 3.0 and 3.8v)
 
thanks, I did, but apparently in the wrong forum as I posted in chip Amps and was directed here. But, finding this schematic, I think I may have been testing rail voltage wrong, so when I get home, I will test it the correct way which I think is one probe on the pad where the two caps join that come from each leg of the rail voltage coming out of the rectifier. Then I can update with some better info and start another thread there.

thanks!