Sound Skulptor forums

Build help and troubleshooting => DI503J Triple DI and Re-Amp => Topic started by: marcspace on February 03, 2023, 03:14:46 PM

Title: R31 problem
Post by: marcspace on February 03, 2023, 03:14:46 PM

Hi guys,

I switch on the lunchbox, the resistor R31 get burned, please help.:'(

R31=5.3 ohm (normaly 5R6)

Thnx

Title: Re: R31 problem
Post by: JPK on February 03, 2023, 04:48:45 PM

Make sure you didn't swap U3 (THAT1512) with U4(THAT1646).
Is is the same without the tube plugged in?
Look for solder bridges, reversed diode, transistor or IC.

Title: Re: R31 problem
Post by: marcspace on February 03, 2023, 06:05:52 PM

;D problem solved,

U3 and U4 swapped!!!


You're the GOAT!!!


thnx

PS: R31 5.3 ohm is fine? better to change it?

Title: Re: R31 problem
Post by: marcspace on February 03, 2023, 07:11:58 PM

Problem test:

all tests passed, Voltage are fine, but 

DI Preamp Check (when I press the button preamp and increase the knob, no I've sound)
DIST Check (the same way, when I press the tube knob the sound leave)


Thnk in advance

Title: Re: R31 problem
Post by: JPK on February 06, 2023, 10:17:39 AM

You have probably destroyed the THAT1646 when swapped.

Title: Re: R31 problem
Post by: marcspace on February 17, 2023, 09:01:55 AM

Hi JKP,

I've changed U3 and U4, now pre amp work fine, but when I push the DIST Botton in tube mode, the sound leaves.

:'(

THAKS IN ADVANCE

Title: Re: R31 problem
Post by: marcspace on February 17, 2023, 04:17:15 PM

Hi JPK,

H=5.6V
HT=46.5V
V+=15.6V
V-=15.5V
TP1=0V
TP2=25.6 V
TP3=0V


Thnx

Mark

Title: Re: R31 problem
Post by: JPK on February 18, 2023, 12:03:45 PM

Check components value and solder joints of C9...C11, R17...R19, L1, TR1, J3, J4, SW3.

Title: Re: R31 problem
Post by: marcspace on February 18, 2023, 01:53:03 PM

All measurements of the capacitors and resistors, such as the soldering, are fine, the switch commute., trimmer goes to 0- 50 k.

The only component I cannot measure is L1.:o (don't have the measuring tool for microhenries)

Thxs

Title: Re: R31 problem
Post by: JPK on February 18, 2023, 05:45:17 PM

You can check the DC resistor which is about 160 ohms.
You can try to follow the signal with an AC voltmeter:
on TP2, R16 top, R17 down, R17 top, R18 down, R19 top, J3 pin1 (square pad).

Title: Re: R31 problem
Post by: marcspace on February 21, 2023, 01:06:54 PM

Hi JPK,

I found the problem it's L1 (no measurement mH, I've bought the tool;))


Thxs for all


Mark