This amplifier came in with its preamp, the model 3600, both in an 'undressed' state with the covers off.
The owner had tried to find the problem after some serious smoke escaped from both pieces of equipment.
The preamp was a relatively simple fix, with a couple of transistors burnt out. Finding out which ones was the challenge, as usual.
This power amp, however, is another story.
Apparently, one channel was blown. On closer inspection, it seems that both channels are faulty.
Looking at the boards, some serious rebuilding and hacking has taken place here, with most of the transistors - in fact all types of components - swapped out for newer ones. Tracks were cut and re-patched, and some serious track burning was evident.
This meant that I couldn't trust anything about it, so a full check - component by component, and connection by connection - was the way to go.
In this video, I tackle the one channel, and take it though to testing.
Some interesting faults were discovered, so I hope this log proves informative to someone out there.
Enjoy.
You can now support the channel:
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Full info on this model:
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DIY TEST GEAR: The title says it all:
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RESTORATION BUILDING BLOCKS: A series of videos showing detailed steps used the restoration process of tube equipment:
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HowTo's: Various videos on some simple techniques and projects:
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See also playlists on some other completed restoration projects.
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LOEWE-OPTA TRUXA STEREO 4741W:
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GRAETZ COMEDIA 616:
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SABA FREIBURG W2:
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GRAETZ MUSICA 4R417:
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CAPACITOR LEAKAGE TESTER:
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Marantz 250M amplifier repair - part 1
Теги
tubevalvetube amptube amplifiervalve ampvalve amplifierrestorerestorationvalve radio restorationtube amplifier restorationvalve amplifier restorationrepairgrundigbrauntelefunkengryphonpower amppower amplifierdual monodim bulb testerpcb repairmarantz250mmarantz 250mmarantz 250marantz ampmarantz vintage ampmarantz stereo amp