(Help) THAT 2181LC in Boss TR-2

[niopren]

Hello,

I need help with a pedal Boss TR2 Tremolo made in Taiwan.
This uses the integrated THAT2181LC which is damaged.
I could not get a replacement for it. Anyone know where to get it or that would be his replacement? 
THAT2181C? THAT2181AL?

thanks.
greatings from Chile.

[garcho]

the 'C' in THAT2181LC is referring to how much THD the company guarantees. LB and LA versions are the same as LC but with less THD (and more cost).

the 'L' is referring to the package, which in this case is SIP. THAT2181SC (or SA, SB) is the surface mount package.

Cool Audio makes a clone, the V2181L

[armdnrdy]

Small Bear stocks the Cool Audio V2181L.

You can purchase the That IC from ebay.

What makes you believe that the VCA is bad?

[niopren]

thank you.


check all IC (except THAT) in a opamp tester, all functioning
(IC http://www.seekic.com/blog/project_solutions/2011/08/18/OPAMP_TESTER.html tester)
Transistors the probe with my Atlas Peak DC55 and my multitester, all functioning.
tester diodes whit my multitester, all functioning.

Use a audio probe, the bypass circuit and input and output buffer all operate.

The signal is lost in R9 it is on pin 1 THAT (IN). (THAT voltages appear normal). In THAT no signal.

(Http://www.hobby-hour.com/electronics/s/tr2-tremolo.php schematic of TR2, earlier)

[armdnrdy]

Here's a working link to the schematic:

http://www.hobby-hour.com/electronics/s/tr2-tremolo.php

So...you used an audio probe and you lose the signal at R9 (10K) and the input of the VCA? (Pin1)
Or...you have signal at the input of the VCA but have no output.

[niopren]

So...you used an audio probe and you lose the signal at R9 (10K) and the input of the VCA? (Pin1)

yes
lose signal between at R9 and pin 1.
when i remove THAT, the signal becomes on R9

[ElectricDruid]

So...you used an audio probe and you lose the signal at R9 (10K) and the input of the VCA? (Pin1)

yes
lose signal between at R9 and pin 1.
when i remove THAT, the signal becomes on R9

Unfortunately that doesn't prove that the 2181 isn't working. What I'm sure armdnrdy was driving at is that the VCA input is a virtual ground node and you wouldn't expect to hear any signal there. Unless you remove the VCA, in which case it's not a virtual ground node, and you will hear something.

So we need another test. What can you hear at the *output* of the I-to-V op-amp stage following the VCA? (the input of that one is a virtual ground too).

HTH,
Tom

[niopren]

in the output of the VCA no sound. (pin 8 )
IC6 (before VCA) pin 7 clean sound low;  pin 1 clean sound normal level
the other Opamp no sound

[PRR]

That THAT chip is current-in current-out.

You should not have signal Voltage at In or Out.

You should have signal before R9 and after IC2a. Both points should be at +4.5V DC.

I would rate a THAT chip failure much less likely than the JFETs used for switching (Q1 Q3). Jumper (D-S) a JFET to pass signal.

[niopren]

That THAT chip is current-in current-out.

You should not have signal Voltage at In or Out.

You should have signal before R9 and after IC2a. Both points should be at +4.5V DC.

I would rate a THAT chip failure much less likely than the JFETs used for switching (Q1 Q3). Jumper (D-S) a JFET to pass signal.

dont have signal after r9
both points should +3.96v

q1 and q3 works (test jumper and remove)