Kyocera R-851 (No Power)

[Hames]

Hello!

Today I picked up a Kyocera R-851 as part of a lot of audio gear, and I’d like to get it up and running.

The guy mentioned that the unit “doesn’t power on, but smokes when you hit the power switch”. Considering the rest of the lot was well worth my money, I figured it was worth a shot at fixing.

After getting it home, and taking the hood off, it seems the issue is pretty obvious:


This is the only component that has any visible damage, and (after looking at the schematic) appears to be:
L501L and L501R

According to the data sheet these are a Choke Coil and a Relay (with: JC2A-48V in the description)

I can’t find a part matching this, but was wondering if anyone here has any ideas.

Thanks!

 

[redk9258]

I don't see the damage. Have you tried to power up with a dim bulb tester?

 

[Hames]

I don't see the damage. Have you tried to power up with a dim bulb tester?

I haven't. To me, it looks like the damage is around the choke coil and/relay. The smoke starts almost immediately, and it comes from right in that region.

 

[jhjove]

I think you have some high DC current flowing through the final output stages on both channels if both coils are smoking.
For sure DO NOT connect any worthy speakers to this unit...although "doesn't power on" could mean protection circuit is working.

If you have a DMM start checking devices in the output stages for shorts. Do this un-powered + not plugged into outlet.


EDIT: This receiver uses a power MOSFET transistors for driver and final stages, one of the main attributes for this model. Very nice.
Hopefully you can get this unit righted.

 

[EC1]

One time I picked up a non working R461, not remembering what were the symptoms. Opened the case looking around and found some missing board mounting screws, reinstalled the screws then it backs to life. They use the screws for grounding. Just FYI. Don’t know this helps yours or not.

 

[Hames]

I think you have some high DC current flowing through the final output stages on both channels if both coils are smoking.
For sure DO NOT connect any worthy speakers to this unit...although "doesn't power on" could mean protection circuit is working.

If you have a DMM start checking devices in the output stages for shorts. Do this un-powered + not plugged into outlet.


EDIT: This receiver uses a power MOSFET transistors for driver and final stages, one of the main attributes for this model. Very nice.
Hopefully you can get this unit righted.

I have a feeling the protection circuit is working, as power doesn’t seem to leave the P.W. Board (no lights to the display or other indicators outside of that first board).

Thanks for the info! I’m really hoping to get this up and running to drive the Thiel CS3’s that came with it (those are in phenomenal shape, so not going to test with them obviously…)

 

[jhjove]

I have a feeling the protection circuit is working, as power doesn’t seem to leave the P.W. Board (no lights to the display or other indicators outside of that first board).

Thanks for the info! I’m really hoping to get this up and running to drive the Thiel CS3’s that came with it (those are in phenomenal shape, so not going to test with them obviously…)

No lights at all?
The speaker protection relay only disconnects the speaker terminals from the power amp section.

The power must be leaving the PWB board (+55V / -55V) due to the coils smoking in the final stage (the PWB powers the main amp).
The other transformer secondary drives the supplemental power supply (+27V / -27V) for the rest of the receiver.

I think I saw only one fuse (main, 8A 250V).
Use a Dim-Bulb-Tester if you attempt the power on further....I'm fairly certain the bulb will be bright (indicates short).