secondslc
mmmmmarantz
**Edit** for more views. I have questions on page 3.
PHOTO INTENSIVE POST....please have patience...Questions in bold.
Well, as my SR9000G nears completion, i decided to pull the 4400 from my setup to evaluate it.
**aside**I bought the 4400 on ebay on accident since I didn't think my bid for 400 would hold up. I just wanted a unit with a working scope, as thats the only part I know would be IMPOSSIBLE to find. It was my first vintage audio purchase, and I thought since I was getting the king of quads...i would not need anything else. Needless to say, i ate those words. **aside**
The 4400 had two obvious problems, the scope had a curve tracer like display. And every time I would play it, there would be a loud pop, the speaker protection relays would kick in, and reset the unit. The pop would not comeback the rest of the listening session. I lived with both problems by playing low volume till the pop, and dimming the scope to prevent burn in.
With any good restoration, you take lots of before shots, and measure offsets. The dial lamps were not all there, so I have LEDs ready to put in as a final touch.
I took offset measurements and was pretty happy with the results. The range was from -.15VDC to .114VDC.
Then I started to do a visual inspection of the unit. This thing was messed with before! There were many hold down screws missing...where can I find scews for this unit??
Then as I hovered over the machine...OH CRAP WHATS THAT.....
Yeah, the pictures I took in December show the same hole in the cap. Before I do ANYTHING else to this unit, these caps need to be replaced. Does anybody have a suggestion as to the cap brand/model number that is the easiest drop in? I may just go with the best one I can find on digikey, should I keep the same values or go any bigger?
I remember reading about the scope board having bad fets. How do I test a FET, or should I just go ahead and replace them? And oh look...the wire that goes to j922 is disconnected, could that be the whole problem? What is the easiest way to pull this board as its still connected to the power supply, should I go ahead and de-solder the connections, or does snipping zip ties underneath allow me enough slack to flip the board and solder?
I was intimidated by this unit for the longest time. But I am confident that I can handle repairing a working 4400 vs a crispy mess.
Any and all advice will be greatly appreciated!
PHOTO INTENSIVE POST....please have patience...Questions in bold.
Well, as my SR9000G nears completion, i decided to pull the 4400 from my setup to evaluate it.
**aside**I bought the 4400 on ebay on accident since I didn't think my bid for 400 would hold up. I just wanted a unit with a working scope, as thats the only part I know would be IMPOSSIBLE to find. It was my first vintage audio purchase, and I thought since I was getting the king of quads...i would not need anything else. Needless to say, i ate those words. **aside**
The 4400 had two obvious problems, the scope had a curve tracer like display. And every time I would play it, there would be a loud pop, the speaker protection relays would kick in, and reset the unit. The pop would not comeback the rest of the listening session. I lived with both problems by playing low volume till the pop, and dimming the scope to prevent burn in.
With any good restoration, you take lots of before shots, and measure offsets. The dial lamps were not all there, so I have LEDs ready to put in as a final touch.
I took offset measurements and was pretty happy with the results. The range was from -.15VDC to .114VDC.
Then I started to do a visual inspection of the unit. This thing was messed with before! There were many hold down screws missing...where can I find scews for this unit??
Then as I hovered over the machine...OH CRAP WHATS THAT.....
Yeah, the pictures I took in December show the same hole in the cap. Before I do ANYTHING else to this unit, these caps need to be replaced. Does anybody have a suggestion as to the cap brand/model number that is the easiest drop in? I may just go with the best one I can find on digikey, should I keep the same values or go any bigger?
I remember reading about the scope board having bad fets. How do I test a FET, or should I just go ahead and replace them? And oh look...the wire that goes to j922 is disconnected, could that be the whole problem? What is the easiest way to pull this board as its still connected to the power supply, should I go ahead and de-solder the connections, or does snipping zip ties underneath allow me enough slack to flip the board and solder?
I was intimidated by this unit for the longest time. But I am confident that I can handle repairing a working 4400 vs a crispy mess.
Any and all advice will be greatly appreciated!
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On one board however, i noticed that a transistor had been replaced, and its heatsink/spacer was missing. The originals are 2sc627, the replacement is a NTE154.
