Boss RC50 schem needed

[Nyqusit5]

Hi there,
Anybody has a Boss RC50 looper schematic? I have one here with dead sub outs and the sm component layout isn't helping me trace the problem...
Cheers!

[Nyqusit5]

Pretty please?

[doctor]

Hi there,
Anybody has a Boss RC50 looper schematic? I have one here with dead sub outs and the sm component layout isn't helping me trace the problem...
Cheers!

Hi Nyqusit5,

If today is not too late, let’s try.

1. First of all, signal exists at SUB OUTs not at each mode. Please check attentively.
2. If at appropriate mode SUB outputs have not signal:

a) check whether inductors L11 and L12 are intact. If they opened or burned, replace them.

Possible replacements:

1. Professional method - chip inductors FLMA-10-160808-601 or similar inductors with
the following parameters: 600 Ohm@100 MHz, Rdc = 0.6 Ohm and 0603 footprint;
2. Semi-professional method - resistors 0 Ohm / 0603 footprint;
3. Amateur method - wire jumpers.

b) If inductors L11 and L12 are intact, check in what part of the circuitry (analog or digital)
the problem is. Firstly check signal presence (by means of scope) on the SUB channel DAC
IC12 (AK4386) analog outputs (pin 10 and pin 11).

I need your reply, and "to be continued".

[Nyqusit5]

Thanks a bunch for the suggestions Doctor. I'll check the L11 and L12 inductor next time I have the unit (the owner is currently using it).

I have to mention that the problem is in the analog domain as I can get the stereo SUB signal by tapping on what looks like two SMD transistors close to the SUB outputs. My problem is that if I connect that signal to the SUB out jacks through capactors, it messes up the balance of all of the outputs (I guess there is a switching jacks connection issue here). Anyway, my point is: the SUB out signal is present on the board but doesn't get to the jack sockets.

Also, the board seems pretty hard to take out because the white ribbon cables don't seem to come off/unplug. Talk about repair-unfriendly construction...

Again, thanks for your help!

[doctor]

Thanks a bunch for the suggestions Doctor. I'll check the L11 and L12 inductor next time I have the unit (the owner is currently using it).

I have to mention that the problem is in the analog domain as I can get the stereo SUB signal by tapping on what looks like two SMD transistors close to the SUB outputs. My problem is that if I connect that signal to the SUB out jacks through capactors, it messes up the balance of all of the outputs (I guess there is a switching jacks connection issue here). Anyway, my point is: the SUB out signal is present on the board but doesn't get to the jack sockets.

Also, the board seems pretty hard to take out because the white ribbon cables don't seem to come off/unplug. Talk about repair-unfriendly construction...

Again, thanks for your help!

Okay, it’s already something.

The question is: you can manage by pressure the signal at both SUB outs simultaneously?

If answer is “yes”, check during pressure mutual control circuits:

1. Whether voltage level on the bases (pin 1) of the muting transistors Q20 and Q23 changes?
It must be “0”.

2. Whether voltage level on the common cathode (pin 3) of the dual diode DA9 changes?
If it changes, note at what levels SUB outs are OK/not OK.

If answer is “no”, let me know.

In any case check connection between CN1 main board connector and cable.

Good luck.

[Nyqusit5]

Okay, it’s already something.

The question is: you can manage by pressure the signal at both SUB outs simultaneously?

Thanks but I am not quite sure what you mean here by "pressure".

I haven't got the unit with me at the moment as the owner is a working pro musician and he is using it right now (albeit without the needed SUB outs), so I can't check. Q20, Q23 or DA9.
I am pretty sure I'll sort this unit out fast once I get the schematic but he can't afford me to take the unit from him as long as I haven't got it because it is a central part of his act.

[doctor]

Thanks but I am not quite sure what you mean here by "pressure".

I haven't got the unit with me at the moment as the owner is a working pro musician and he is using it right now (albeit without the needed SUB outs), so I can't check. Q20, Q23 or DA9.
I am pretty sure I'll sort this unit out fast once I get the schematic but he can't afford me to take the unit from him as long as I haven't got it because it is a central part of his act.

I meant that you press on main board (for example, by finger).

[Nyqusit5]

Ok, I get it.
I employed the verb "to tap" as "to take the signal from", and not "to hit" or "to knock".
There is no loose connection or solder joint, at least none that is reinstated by a knock on the board. Sorry for the confusion and thank you for your perseverance!

[Nyqusit5]

Still looking for that schematic...

[Nyqusit5]

and yes, still looking...