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New Project Marantz 2250b
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Old 28th January 2018, 05:32 PM   #11
pjf610 is offline pjf610
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OK get back to you tomorrow

Thanks
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Old 28th January 2018, 05:40 PM   #12
Mooly is offline Mooly  United Kingdom
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New Project Marantz 2250b
OK
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Old 29th January 2018, 04:10 PM   #13
pjf610 is offline pjf610
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Think i found the culprit,Burnt out resistor, i need to order some parts so i will get back to all when i get them
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Old 29th January 2018, 05:13 PM   #14
Mooly is offline Mooly  United Kingdom
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What is the reference number ? It didn't go like that on its own.
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Old 29th January 2018, 05:45 PM   #15
pjf610 is offline pjf610
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R731 I would not know at this point I will be pulling out H714 and H715 to test them, I guess i will order new ones, only because they will be out why not replace them, and i will keep moving forward from here
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Old 29th January 2018, 06:10 PM   #16
pjf610 is offline pjf610
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Am I to assume that when replacing a component to look for a updated replacement or if possible replace with the same if it is still available???
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Old 29th January 2018, 09:45 PM   #17
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Some good news i pulled and checked the H714 and 715 the were OK now have to wait for the resistors to get here will keep you posted
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Old 30th January 2018, 08:40 AM   #18
Mooly is offline Mooly  United Kingdom
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New Project Marantz 2250b
R731 is one of the emitter resistors on the driver stage.

The most likely scenario is that the failed output transistor caused the 0.22 ohm emitter resistor to fail open circuit leaving the driver transistor and the 220 ohm to try and deliver all the fault current.

You need to be very very sure these are all OK. If I was repairing this I would look to replacing the drivers and H707 as well using modern parts. The original failure of the output transistor could well be caused by a problem earlier in the amp.

Modern semiconductor replacements mean that the circuit may need tweaking to remain stable against oscillation and instability and also thermally stable.
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Old 1st February 2018, 11:45 PM   #19
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Still waiting for parts but i have a question I want to check the outputs using an Oscope, I have a tecktronics 2232 OS, a Fluke 6070A signal generator, and a HP 8116 function generator, these units was handed down to me from my uncle. My question is what type of connector do i use? I have a bnc to rca but it is not split only 1 rca at the end, so my question is when i plug the bnc into the signal gen. i plug the rca into the aux.how do i read 2 channels or do i have to switch the rca to each right and left every time i what to see each channel. I watch the videos on YT and they can switch from left to right on the OS do they use a bnc cable with 2 rca plugs on the end???
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Old 2nd February 2018, 07:21 AM   #20
Mooly is offline Mooly  United Kingdom
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New Project Marantz 2250b
You either have to make a suitable lead up, or you could tag a wire between two of the input sockets internally in the amp to link L and R on a suitable set of inputs.
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