Looking for Mentors to fix a DOA CA-800

Yamaha Dean

New Member
CA-800
View attachment 1092982 View attachment 1092982 View attachment 1092985 Upon inspection I noticed that some of fuses were broken (1 on each side). I cleaned the unit out with 2 cans of Sprayon EL2302 and then replaced the fuses and 2 broke again only this time on the right side as you face the unit. The power light does come on. Please walk me through the process of checking what might be the source of the problem step by step. I'm a beginner/newbie and would like to learn so go easy on me :). Hopefully I can find some people that are willing to teach me how to repair this great looking CA-800. I will post pics as we do this repair together step by step.

I have downloaded the repair manual for the CA-800 and have all the tools required for the job maybe not the parts.....

I have the unit open. Control knobs are off along with the faceplate. I put all screws in baggies and number my steps and take pics. The unit is very clean inside and I'm ready to troubleshoot. Please when offering advice can you send pics or refer me to the CA-800 diagram and explain things to me like I'm a 1st year college student. I what to do step by step. I'm a quick learner however I just need over simplified guidance at first.

Thank you for the much needed help/guidance.
 
without looking at a schematic they appear to be the fuses for the main b+ b- rails . first thoughts are blown output devices and more . not sure about why that resistor would burn without seeing the schematics .
am sure the resident expert will appear soon .
 
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That large capacitor with the shrunken sleeve is history.
 
Resistors don't just burn up. You have either a shorted transistor,diode or (electrolytic capacitor).
 
Post a photo of the power supply circuit board . Its visible from the bottom of the CA-800.
 
If your burning up the rail fuses.On both channels... Houston we have a problem..
 
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See the transistor pressed against the big heatsink with the brass/copper spring. It is not original. The original was a 2SC458 "TO-92 outhouse style". That transistor thats there now is a TO-92 standard .Looks like someone else has been in here. Hope fully that transistor is a suitable substitution.
 
on another note have had the rare occasion with a flaky output transistor socket that had same symptoms . drivers took a hit driving the speakers .
 
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