e-licktronic Forum

Do you have an AC mode on your multimeter ? If yes, what does it say ?

gihaume wrote:Do you have an AC mode on your multimeter ? If yes, what does it say ?

Cheers for responding this quickly. The new power adaptor has arrived and the same thing is happening, so it’s obviously not the one to blame. At +15V output I get over 18V measurement and rising, at -15V only 0.83

Hey Ambicumber,

did you get any closer to a solution yet?

good luck!

Hey m8. unfortunately still not. Will post any progress here for others to see, if this happens

ambicumber,

First you have to disconnect power supply from the IO board to the mainboard.
1/Could you confirm that your wall wart PSU is a 15VAC at least 600mA ?
2/Then test +15V, +5V and -15V with your MultiMeter in DC mode, what are the result ?
3/Check that D109, D110, D11, D104 and D94 to D97 are in the right way ?

Then let me know.

Thank you Vincent for helping me out!

e-licktronic wrote:ambicumber,

First you have to disconnect power supply from the IO board to the mainboard.
1/Could you confirm that your wall wart PSU is a 15VAC at least 600mA ?

I confirm that, even bought a new one during troubleshooting so I have two.

2/Then test +15V, +5V and -15V with your MultiMeter in DC mode, what are the result ?

(Edited here because I changed the multimeter!)

+15V = 15.20 V
-15V = -18.20 V and fluctuating at J8
Pin 3 at J10 = 4.70 V
Pin 7 and 8 at J10 = 4.97 V

3/Check that D109, D110, D11, D104 and D94 to D97 are in the right way ?

Then let me know.

All are put in the right way.

OK, update here:

As Vincent instructed, I replaced the REG2 again and got stable voltages as follows:

15 V = 15.19 V
-15 V = -15.19 V
5 V = 4.98 V

I have now connected the mainboard to the PSU board. Now the mainboard problem is as previously stated in this forum thread:

I have no cymbal sound (CH, OH, CY and also PC2) both on individual and mono outputs. Also, clap sounds a bit weird - it is very quiet, dim, and seems to lack the crispyness. Accent seems to have no effect on sound, and I don’t hear any difference in handclap when rotating TM3.

Will update until the issue is resolved

I have replaced U3, but that didn't help. Upon scoping the cymbal noise section I found that the hex inverter (U4) has good square wave noise output at pins 2, 4, 6, 8, 10 and 12 looking like this:



At pins 1, 3, 5, 7, 9, 11 and 13 I get this which is also probably fine:



Can you confirm these t-bridge outputs at U3? This is the output of U3 (4558) pin 1:



And this is the output of U3 at pin 7:



Any idea what I should troubleshoot next?

After modding a speaker, I can clearly hear the square waves at hex inverter U4, however, at the outputs of U3 there is only very faint noise. Changed a couple of 4558s and even TL072 but no change.