TOA 900 SERIES AMPLIFIER P-912MK2

August 6, 2019 posted by

Let’s go with R as 27R sch typo is R and look for trouble elsewhere. It looks like the same family or or just different power output. You can start at the power supply, the amp input, the output, the middle etc. Note the polarity of the voltage if it is not zero. United States I’m a: Order in the next 0: That circuit also drives the protection led That pc board has been running hot for a long time to do that, it did not just turn dark all of a sudden. What is the voltage that is measured at L or where the two.

I would start testing transistors in the power amplifier section, and look for burnt parts. If OP can measure some voltages on the transistors, or just keep testing parts. The output transistors, drivers, pre-drivers, emitter resistors I would test. They are rock-solid reliable and have many module choices for auxiliary functions. At CN , I get a voltage reading of In Stock Update Location close.

Thanks, I will double check those resistors and reverse the leads to see if the readings change. For further details see delivery estimates in cart. TOA series ii Amplifier PMK2 I also failed to mention that there is a portion of the board which appears to have possibly overheated. Originally Posted by redwire Typically, shorted power amplifier transistors trip the DC protection circuit. I agree that they appear to have been running very hot.

There are about 5 diodes in total that I am getting questionable readings from, but again I am new to this so maybe I am not testing properly? I just cant seem to find it. See attached schematics and troubleshooting guide. Don’t forget to order the input module separately if you need one.

TOA 900 Series II Amplifier P-912mk2 120w Single Channel

Find More Posts by Bterrier. If you can post the schematic you obtained, that would help. Have you checked the thermal cutout listed as thermostat Check the voltages on M protection ic it also drives the relay.

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Please check your local sales tax laws. For the diodes, D gives me a reading of 0. Usually these voltage amplifier stages use TO package parts and they run warm and need small heatsinks. It looks like the same family or or just different power output. Enter new zip code to refresh estimated delivery time.

The protect light is on and the amplifier will not function. It has a single module slot for easy custom configuration using TOA plug-in modules. R is R on the schematic but pic looks like 27R installed on this board??? That could cause it. Send a link to this item so recipient can review, customize or exchange for an alternate of equal or lesser value.

I see TOA forgot protection diodes to the massive 70V line output transformer, so it’s not a tough tox despite the reliability claims. They are rock-solid reliable and have many module choices for auxiliary functions.

R at 27R sorta matches the listed voltages for about 6. I sereis not find a service manual or schematic for the “P” series, but did for the “W” series wall mount and “A” series, like AMK2 which may be similar. Note this amplifier uses a servo circuit op-amps M which work to keep the idling output at 0VDC.

Order in the next 0: They have a square symbol next to them on the schematic. The system also has a direct input so that it may be used without an input module. The point is to be a detective and have fun. Union City My Country: You can NOT look at a transistor and say it looks ok, you need to at least check them with a meter, even if the transistor is leaky or if a resistor is ie higher than its value is enough to unballance the amp and trip the protection circuit.

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I have my DVM set to diode seriss when testing. sfries

TOA series ii Amplifier PMK2 The 3 pin resistors are just two resistors with a common center pin the single pin endthey should read. That circuit also drives the protection led That pc board has been running hot for a long time to do that, it did not just turn dark all of a sudden.

Not Specified by Manufacturer. Also tested many of the resistors and there are a few which are questionable to me.

PMK2 | TOA Corporation

Otherwise, the resistors are damaged I would say. Also I did disconnect some connectors one at a time from the mainPCB to see seriies I could isolate the issue. See any errors on this page? And check continuity between L and relay contact where R connects to relay That will check the thermal cutout M drives the relay, the relay contacts are S1 that connect the amp output to the speakers. I am getting a reading on both at 1.

I have only done a basic visual inspection to ensure the issue isnt obvious checked fuses on board. Page 1 of 3. International orders are processed the next shipping day.

TOA P-912MK2 900 Series Single Channel 120 Watts Power Amplifier

D gives me a reading of 0. Typically, shorted power amplifier transistors trip the DC protection circuit.

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