I replaced the original 10uf 575v electrolytic cap in the scope circuit with a 10uf 630v solen pp film. Scope display was cleaner - easier to focus and brighter - but the alignment settings are way off. When I set the horizontal all the way left the dot only goes as far as the middle. Same for the vertical. It only goes as far as the middle when set at the max downward adjustment. Would you expect the different cap types to cause this? Any ideas? Thanks.
Marantz 18 Scope
- Thread starter Douglie
- Start date
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- Tags
- marantz 18 marantz scope
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The first thing to keep in mind is you are working with high voltage! If you are not getting your ~-500 volts it could be in the power supply. The transistors on the scope board (Q1202/3 and Q1205/6) are also known to cause this type of issue. Voltages are listed on page 26 of the service manual.
Tony
Tony
Yes, I understand the high voltage. I appreciate the warning and quick response. I have right at -500v at the capacitor from about -480v before the change. Thanks.
I just had another problem that prevents me from turning the receiver on. It’s a completely different issue so I’ll do a new thread.
I just had another problem that prevents me from turning the receiver on. It’s a completely different issue so I’ll do a new thread.
I replaced the six transistors on the scope board and it came back to life. I think it was a bad FET but hard for me to tell since I did them all together. One thing I ran into is the new FETs that I got (which were the ones listed on the model 18 parts thread) had a different pin out than the originals. They work fine after I played pin twister but just something to be aware of.