Primare A30.1 - The speaker protector cut off the speaker from the power amplifier - diyAudio
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Old 24th January 2013, 01:05 AM   #1
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Default Primare A30.1 - The speaker protector cut off the speaker from the power amplifier

Hello Everyone,

I have a Primare A30.1 integrated amplifier having a problem on the right power amplifier. The speaker protector do not connect the speaker to the power amplifier when it is powered up, because there is a 0.6VDC at the power amplifier output.

I have soldered a speaker to right power amplifier's output, it can have music output without hearable distortion. What component you would suspected to cause the DC offset??

Thanks for any input!

Best regards,
William
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Old 24th January 2013, 02:52 AM   #2
bx19 is offline bx19  Hong Kong
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Hi,

William and I are working this amplifier.

Seems to me that this integated amplifier is using BTL output. Speaker is floating, not on ground. It is difficult to find out which component caused the offset. Hoping somebody can shed some light on this.

There are 2 big power transformers for L and R channel. Each transformer only has one output winding (28V ac, no center tap), feeded to the bridge rectifier.

4 big transistors are used on 1 channel, they are not connected as parallel. Instead, they are 2 separate outputs, speaker is connected at BTL.

No idea whether the 0.6V trigger the speaker protector. Or there is a problem on protector circuit.

We do not have Primare 30.1 integrated circuit diagram.

Best regards,
Norman
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Old 24th January 2013, 05:25 AM   #3
JMFahey is offline JMFahey  Argentina
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Try to get a schematic, otherwise it's just a guessing game.
Worst case, lift it yourself with paper and pencil
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Old 24th January 2013, 05:36 AM   #4
bx19 is offline bx19  Hong Kong
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Yes, I agreed, it is difficult to find. Appreciate any reply. Already with pencil and camera to scratch the circuit. They used surface mount, difficult to trace.

The protection circuit used two units of surface mount Philips NAND gate HEF4093BT to drive two 24V relays. Both relays do not latch.

No idea why both relays not latched if RHS having 0.6VDC, LHS is normal (LHS relay should latched).
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Old 24th January 2013, 06:21 AM   #5
bx19 is offline bx19  Hong Kong
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Next step is to use two units of small VA transformers to replace the big one for indepth troubleshooting.
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Old 24th January 2013, 11:36 AM   #6
bx19 is offline bx19  Hong Kong
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It is difficult to find the circuit diagram.

Appreciate anybody can help on giving me the circuit diagram, or a portion of it which focus on the line amp and the power amp section.

Thanks and best regards,
Norman
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Old 24th January 2013, 11:53 AM   #7
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If you find a problem with a surface mount part, are you going to buy a $600 hot air soldering station to repair it?
Cheaper to salvage the power transformers and heat sinks, maybe salvage the output transistors and relays, and buy an amplifier board with components with leads on them. Or make one with perf board. diyaudio.
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Old 24th January 2013, 12:58 PM   #8
JMFahey is offline JMFahey  Argentina
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Go to the source, ask Primare themselves.
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Old 24th January 2013, 02:40 PM   #9
bx19 is offline bx19  Hong Kong
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I have the soldering tool. In fact, I would like to preserve the unit in original shape and design. Also, I wanted to reduce soldering out unrelated component during trouble-shooting.

Primare may not release the circuit because I am not their dealer.

Best regards,
Norman
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Old 24th January 2013, 03:42 PM   #10
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Is the A30.2 just the poweramp from the A30.1?
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