Proton D940 Stereo Receiver Repair

Proton D940 Stereo Receiver Repair - part 1

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Жыл бұрын

Follow along as I repair a Proton D940 stereo receiver that has several problems. #electronicsrepair #amplifier #audioequipment

Пікірлер: 11

@BjornV78 Жыл бұрын

46:10 That glue under the microcontroller that became conductive can be the reason that the memory capacitor next to it gets drained over time.

@jonathanhendry9759 Жыл бұрын

You may already know but there's a technical bulletin suggesting a fix for a hum in one channel. It's in the service manual I downloaded from HiFiEngine. This is Relevant To My Interests. I have a D940 that I need to get around to fixing. The tuner section including the display just doesn't function. Other inputs still work fine. So I'll be watching intently to glean what useful tidbits I can. I bought my first D940 from Crutchfield back in the 80s when I was in high school. Used it with a Sony D-7 Discman. It was disposed of at some point but I bought another a year or so ago.

@jonathanhendry9759 Жыл бұрын

This may have been user error but I tried running an equalizer using the Pre-Out and the results were not good, compared to using a tape loop. The first EQ I tried it with was very noisy, which I attributed to the EQ being crap. The second EQ I tried had the blinkenlights spectrum display, which was not lighting up in the expected way when hooked up to the Pre-Out, but worked as expected when connected to a tape loop. I'm not sure the "pre out" actually has the expected tone and volume adjustments applied. I suppose the schematic might show whether that's the case.

@EriksElectronicsWorkbench Жыл бұрын

I did not know about the bulletin but will look for that on HiFiEngine. This unit doesn't have a hum issue but still good to know about. I have fixed two other of these D940's and the others were defective from broken solders. One had a non working display and was a cracked solder causing the issue.

@EriksElectronicsWorkbench Жыл бұрын

@@jonathanhendry9759 I think an EQ on a tape loop is probably the best setup generally speaking. I have used the D940 pre-out to drive other power amps and these units work well as a preamp.

@jonathanhendry9759 Жыл бұрын

@@EriksElectronicsWorkbench The bulletin says to replace four .01uF 50V capacitors with .1uF 50V capacitors. C943, C944, C945, and C946. Along with instructions on how to access them and how to route some ribbon cables that need to be disconnected. "It has been noted that certain D940s exhibit 25-50 mV hum at approximately 120hz out of one or both channels with no source selected, volume at minimum and treble control at detent position."

@user-hy6vj7ws1g 6 ай бұрын

What method(s) &/or chemical(s) do you use to remove the old glue from the PCB and components? Thank you.

@EriksElectronicsWorkbench 6 ай бұрын

Isopropyl alcohol helps soften but it is mostly scraping away with a small screwdriver tip.

@petenamlook18 Жыл бұрын

That sure looks a lot like an NAD in a different package.

@EriksElectronicsWorkbench Жыл бұрын

Yes suspiciously similar 🤔

@EriksElectronicsWorkbench Жыл бұрын

The label on this unit says manufactured by Fulet Electronics Co. That company produced the Proton brand and some NAD as well. I have heard there are also other Proton and NAD models that are basically identical.