So 1K preset for VR2.
1K between the C-B of the MCE840. And it's all a very cheap modification too
Would I still need to set bias for 40mA according to the service manual? Bearing in mind also the drivers and outputs are now modern devices, any advantage in pushing it a little higher to the 50mA of your sim?
If you think those values are now sound I'll order them. Will wait a week or two before installing though as still giving the amp its trial period following the recent fixes and so forth. Want to make sure no other issues are forthcoming before I change the biasing method. The MJE840 I could probably attach via one of the TO3 mounting screws to the transistors outer 'wing'. So it'd be right up close to the transistor.
1K between the C-B of the MCE840. And it's all a very cheap modification too
Would I still need to set bias for 40mA according to the service manual? Bearing in mind also the drivers and outputs are now modern devices, any advantage in pushing it a little higher to the 50mA of your sim?
If you think those values are now sound I'll order them. Will wait a week or two before installing though as still giving the amp its trial period following the recent fixes and so forth. Want to make sure no other issues are forthcoming before I change the biasing method. The MJE840 I could probably attach via one of the TO3 mounting screws to the transistors outer 'wing'. So it'd be right up close to the transistor.
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1k, for the preset, 1k for the resistor. What's an MCE840 we'll use one of those anyway
Bias is set as per the manual, I said 50ma didn't I, was just going from memory.
Remember that the MJE devices have a metal tab at the back that is electrically connected to the collector. So they need isolating.
we'll use one of those anyway Bias is set as per the manual, I said 50ma didn't I, was just going from memory.
Remember that the MJE devices have a metal tab at the back that is electrically connected to the collector. So they need isolating.
OK, will stick to 40mA then
Could one mount the MJE on its back, with perhaps just a light dab of thermal compound? That way it'd be neatly insulated, without having to use any mica or silpads, and I could simply just use a nylon washer underneath the TO3 mounting screw to prevent it shorting out the exposed metal side. Doubt it would compromise its thermal tracking abilities having it mounted 'backwards', by any significant 'degree' (pun slightly intended!)
Could one mount the MJE on its back, with perhaps just a light dab of thermal compound? That way it'd be neatly insulated, without having to use any mica or silpads, and I could simply just use a nylon washer underneath the TO3 mounting screw to prevent it shorting out the exposed metal side. Doubt it would compromise its thermal tracking abilities having it mounted 'backwards', by any significant 'degree' (pun slightly intended!)
Ah that's handy. So I could use a 1K smd resistor on the legs of the mje840 - that'd be the neatest solition I think. Easier to insulate the legs & solder connections to the wires with heatshrink with the resistor butted up next to the body of the multiplier. And will mount it front first too then.
http://uk.rs-online.com/web/p/surface-mount-fixed-resistors/6787150/
Great. Will order those parts now
Thanks Mooly.
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Have had to shelve this project temporarily, due to the delights of what appears to be a herniated disc and a possible trapped sciatic nerve too. Heavy amps are a no-go area right now. Frustrating.
Have got the parts for the VBE mod though, and touch wood will be able to get cracking with it again once I have sorted my back sorted out. In the meantime, I have a much smaller and far lighter Naim NAP120 to recap and restore... And here was I saying 1st January one of my New Year resolutions was to stop mucking about with Hi-Fi......
Have got the parts for the VBE mod though, and touch wood will be able to get cracking with it again once I have sorted my back sorted out. In the meantime, I have a much smaller and far lighter Naim NAP120 to recap and restore... And here was I saying 1st January one of my New Year resolutions was to stop mucking about with Hi-Fi......
Hi all,
To continue on Akai AA-1020 amplifier, may be anyone got some idea ...
I just restored one of these receivers: new caps, adjustment & cleaning.
One channel was bad, I replaced all 4 output transisotrs with 2N3055 and I also adjusted voltages in amplifier.
Receiver works good for aprox. 10 minutes.
After that one channel stops working.
TR5 and fuse for that channel blows.
What can be wrong ?
Tnx
To continue on Akai AA-1020 amplifier, may be anyone got some idea ...
I just restored one of these receivers: new caps, adjustment & cleaning.
One channel was bad, I replaced all 4 output transisotrs with 2N3055 and I also adjusted voltages in amplifier.
Receiver works good for aprox. 10 minutes.
After that one channel stops working.
TR5 and fuse for that channel blows.
What can be wrong ?
Tnx
