No headphone output from electronic drum kit, which capacitors to replace?

[Bassquake]

I have a Session Pro DD505 electronic drum kit which no longer has sound coming out of headphone jack. The Line Out Left and Right outputs are fine though.

I replaced the headphone socket to rule out a connection issue.

I suspect its the caps as it worked for a while, then the sound started "blipping" and failing, and now no sound. They all look fine. But am not sure which ones to replace. Maybe the bottom 6?

I've attached some photos of the device.

Help appreciated.

[stj]

Re: No headphone output from electronic drum kit, which capacitors to replace?

i cant read the number, but concentrate on that 8pin TDA amplifier between the caps.
it may be bad, or it may have lost power.

it wont be caps unless they are power related because you wouldnt have both channels effected - presuming it's actually stereo

[Bassquake]

Re: No headphone output from electronic drum kit, which capacitors to replace?

Hi. The chip is a TDA1308.

I did a volt check on the pins. See image below for result. I dont know if theyre ok or not as I dont know much about ICs!

[stj]

Re: No headphone output from electronic drum kit, which capacitors to replace?

data

[stj]

Re: No headphone output from electronic drum kit, which capacitors to replace?

strange readings, the outputs are equal to the inputs

[petehall347]

Re: No headphone output from electronic drum kit, which capacitors to replace?

where did you put your black meter probe ? and is that v or mv ?

[redwire]

Re: No headphone output from electronic drum kit, which capacitors to replace?

Voltages on U18 TDA1308 look fine, single 5V supply so 1/2 that on all ins and outs.
Q6 and the other might be muting transistors which also get damaged from ESD when you plug in headphones, there can be quite a zap.

With headphones plugged in, touching a multimeter probe to U18 inputs pin 2, 6 should make noise you can hear.

[Bassquake]

Re: No headphone output from electronic drum kit, which capacitors to replace?

where did you put your black meter probe ? and is that v or mv ?

Black was on pin 4. Multimeter was set on 20 on the VDC setting.

[Bassquake]

Re: No headphone output from electronic drum kit, which capacitors to replace?

With headphones plugged in, touching a multimeter probe to U18 inputs pin 2, 6 should make noise you can hear.

Should the device be on for this? And do you mean to short pin 2 and 6? Or do mean just prod those pins and I should hear something?

[redwire]

Re: No headphone output from electronic drum kit, which capacitors to replace?

It's what I would do as a quick test- with the unit powered up, just touch the multimeter's probe to either pin 2 or pin 6 and listen for the click/hum buzz in the headphones. Looking for signs of life there. Do you hear anything at all, thumps or clicks, powering up/down?
I would also trace Q6 connections and see if it is a muting transistor for the headphone output. A theory is one L/R has shorted.

[Bassquake]

Re: No headphone output from electronic drum kit, which capacitors to replace?

After poking around some more (literally!), I found if I pushed using plastic tweezers on the black resistor (I assume its a resistor) marked on the photo below, the sound would return!

So I thought I'd resolder its joints if its a cold join but it immediately broke which tells me the resistor was already damaged. One of the sides contacts came clean off.

I assume its a resistor so hoping you guys can tell me. And how can I find out its value as I can't get a reading on it.

Edit: Looking at the text box next to those smds it looks like its L3 (attached pic). Is that a diode?

[stj]

Re: No headphone output from electronic drum kit, which capacitors to replace?

it's an inductor - you can probably get away with a jump wire

[Bassquake]

Re: No headphone output from electronic drum kit, which capacitors to replace?

it's an inductor - you can probably get away with a jump wire

Oh right. Before I try that. Do they come in different values? If so, how'd you find it out so I can buy some just in case? I managed to get a Ohm reading of 00.3 when set to 200 on the multimeter if that helps? I got same reading on the L2 and L1.

Edit: I jumped the L3 and I get sound normally in Right channel now. No sound in Left though.

[Bassquake]

Re: No headphone output from electronic drum kit, which capacitors to replace?

Ok. I figured out the Left channel issue. Apparently the trace to L1 wasnt working so put a wire in and it works now. See photos.

You'll notice I jumped L3 too. Now get sound from both channels.

Thanks for all the help everyone. 👍

[stj]

Re: No headphone output from electronic drum kit, which capacitors to replace?

to answer your other question, they do come in different values,
but without the schematic or a component analyzer / LCR meter you have no way to know the value.

[Bassquake]

Re: No headphone output from electronic drum kit, which capacitors to replace?

to answer your other question, they do come in different values,
but without the schematic or a component analyzer / LCR meter you have no way to know the value.

Yeh, I've ordered an inductance meter so I can find out. Been needing one anyway! Thanks.