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Rowe Ami R1-2 Amp Help

reay_d

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reay_d Newbie

reay_d

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Hello All,

I've been working on my Rowe R1-2 for some time now as a side project.

 

It has been a journey with almost every component needing some attention. Firstly the main power supply was rebuilt, Then all the computer, control, memory units and encoder were attended too (with a lot of hair pulling), then the scan control/record changer was adjusted. Everything is working fairly reliably as far as selection goes.

 

So the last piece of my puzzle (before the cabinet refurb) is getting some sweet sweet audio from her. She has a 64watt stereo amp p/n 602-02179.

 

I have been thought this piece to the best of my ability, changing out diodes and caps as required, but can't seem to put my finger on it. I have made considerable progress as I had no sound to start with and the mute relay was u/s. Now the last niggling problem is it keep blowing the Q1 Transistor on the left side driver board. As these Q1 transistors (MJE6041) aren't cheap or easy to come by I'm seeking some help in resolving this.

 

I believe I have isolated the issue to the pre-amp board, when I switched the driver boards over (left to right, right to left) the fault stays on the left side. I can't seem to find anything obviously wrong on the pre-amp. I'm happy to start changing out transistors on the pre-amp but I'm struggling to find replacements.

 

Sorry for the long post but I wanted to provide as much detail as possible. Any advice anyone can offer would be very much appreciated.

 

Thanks in advance,

Danny

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Homepin Ultimate Backyarder

Homepin

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Welcome to AA

 

The MJE6041 is just a darlington, NPN transistor 8A 80V. It's nothing too remarkable and you could probably find and equivalent BDxxxx or something else with some research.

 

The other transistors will all have common (Australian common) transistors - rather than the seppo ones in the unit. Post up the numbers for some suggestions.

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reay_d Newbie

reay_d

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Thanks Homepin,

My understanding of transistors is basic, a quick search tuns up the 2N6491 as close to MJE6041. I wasn't sure this would be compatible as the Transition Frequency (ft) is just higher than MJE6041 and don't understand the effects of that on the circuit. Other transistors I'm looking for are TZ1205, SPS6978, SPS6979 and SPS6980.

 

As well as advice on transistors I was hoping to find someone on this forum that had experience with this amp or similar models. While i'm sure replacing all components logically will eventually fix the problem (how i've gotten through the rest of this rebuild) I'm hoping to streamline this process and get the best sound possible out of this old girl. After all, i'm only fixing her for the love of that vinyl crackle.

 

Thanks again.

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Homepin Ultimate Backyarder

Homepin

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Sadly replacing transistors "one by one" will not work with a transistorised amplifier because they are all interconnected and a new transistor fitted could fry instantly upon power up.

 

It is going to require someone with a good knowledge of solid state repairs to sort out your issue.

 

I haven't fixed these for over 30 years so I'm not a lot of help to you.

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Pac-Invader Contributor

Pac-Invader

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Hello..

sorry for digging up this old thread, but i'm new here & looking to see what i can help with..

The MJE6041 is long gone obsolete & was an odd packaging with NO plug & play replacement..

best option would be track down a known working unit for re-build..

or even better still up-grade to a 125 watt amplifier that uses the more common transistors

by memory the high out-put amplifiers were only ever offered as an option & not normally sold with..

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