Help with 1970s Guyatone Moving Box Flanger - SAD1024

[clarisso11]

Everything has to follow a pattern.
And need a resistance between the emitter and the Anode

Thanks, do you mean the cathode? The schematic shows a 3.9k resistor between cathode and Q1 collector, I measure 4k.

[x-pro]

Rx-?

[clarisso11]

Rx-?

I have connected D1 anode back to ground, and Rx=0 ohm

Edit: This is with IC4 and IC5 removed

[x-pro]

Raise one pin of D3, and check Rx again.
If it is still 0, unsolder the chips one by one.

[x-pro]

maybe C22 in short?

[clarisso11]

With D3 lifted, Rx is still 0.

I will start unsoldering !C1-4. How do I know which one is bad, what should Rx be?

[clarisso11]

maybe C22 in short?

I checked C22 with ESR meter and it looks good

[clarisso11]

Raise one pin of D3, and check Rx again.
If it is still 0, unsolder the chips one by one.

I have removed all chips (IC1-6), Rx is still 0 (continuity between DC rail and ground)

[x-pro]

Q3 remove

[clarisso11]

Unsolder the chip, apply 18 V to the power socket and measure the voltage between emitter Q1 and anode D1

All ICs removed (1-6), voltage at Q1 emitter is very small (~160mV), voltage at D1 anode is 0V. Q1 runs hot quickly

[x-pro]

Is Rx equal to 0 or is there a resistance? In both directions, if the probes of the device are reversed.

[clarisso11]

Rx is definitely 0 ohm, and there is continuity between IC1-4 pins 4 and 8 (V- and V+)

[x-pro]

Maybe you soldered something badly and shorted it out?

[x-pro]

delete Q3, C26

[x-pro]

Connect the LED like this, but remove transistor Q1 for now. The brightness of the LED will indicate a short circuit. As soon as the short circuit is gone, the brightness will drop significantly or not at all.