Thoughts on a dead Line 6 DL4?

[Manolo Dudes]

VERY interesting thread. ¿Wanna see the motherboard of my DL4?:

DL-4 Board

More shots here

[Processaurus]

I just "fixed" my DL4 thats been taunting me for 2 years now, it was being really weird, nothing as simple as the power supply issue thats been talked about here, though the schematic Mr Huge posted of the PS has been helpful with some other mods.  The DL4 was just making crackles instead of delay sounds, but certain things still worked in the DSP, like the dry signal, and some of the non delay effects, like the swell, sweep, and the overdrive in the tube echo model.   In the looper sometimes it would work right, but then it would crackle and skip part of the loop.  What I imagined was that it was like the memory of the loop was being read and all of a sudden, it would read it super quick and the loop would take milliseconds, and would just sound like a crackle.  I tried replacing the crystal, but that didn't do anything, also all the clock test points were consistent, even when it was screwing up.  I replaced the DRAM with another one and it did the same thing...

What I ended up doing was taking apart my functional FM4, using the heat gun to desolder the DRAM off the DL4, sticking the DRAM on the FM4, and switching the eproms and enclosures.  So far both of them work fine.  Lord only knows why .  I must admit they're pretty fun pedals for making weird sounds, especially with my archaic guitar synth.  Tasteful?   Pretty unlikely.

[Tubebass]

Whoops! Wrong thread!

[Manolo Dudes]

Here we go again

My DL-4 (SW version 1.3) started acting erratically for the second time in a year. The first time it was a matter of bad power surge.  Now the power outlet in under specs but I think the failure is still related to power issues. I feed it with a DIY adapter, simply a 220V-9V 1A AC-AC transformer in an old box of slides  but tensions are OK. The DL4 was acting erratically, sometimes working but hanging shortly after. Sometimes hanged when pushing any of the stomp buttons, sometimes when rotating the models encoder, sometimes by itself... 

I dismantled the unit (*) and all voltages were OK for the Zener, charge pumps and regulator as stated previously but found that C40, the big PS filtering capacitor (1000uF 16V) near the power jack was a bit too hot for my tastes. I've replaced the capacitor and now the DL4 works again as a charm. Perhaps the capacitor was faulty and the ripple was upsetting the digital circuitry...


(*)
Board (big pix): http://www.pisotones.com/varios/DL-4/PCB.jpg
EPROM: http://www.pisotones.com/varios/DL-4/EPROM.jpg
Pot shafts without buttons: http://www.pisotones.com/varios/DL-4/Potes.jpg
Detailed view (be careful when prying  ): http://www.pisotones.com/varios/DL-4/TWEAK.jpg
Under the hood: http://www.pisotones.com/varios/DL-4/Pulsadores.jpg
Actuator: http://www.pisotones.com/varios/DL-4/Pulsador.jpg
Dismantled actuator: http://www.pisotones.com/varios/DL-4/Pulsador_despiece.jpg

[Manolo Dudes]

Alright, I give up! 

I've tried all I can imagine and then some... The DL-4 works 1 out of, say... 10 times, but when it works (works OK with all delays) it hangs a few minutes later.

I've measured voltages. All are OK as stated above in this topic ( D16,  U14, U20 and U21). Same with 9V AC, 9V DC or batteries.

I've replaced all electrolytics and some tantalums.
I've replaced both 1N4002 rectifiers and the 3.6V Zener
I've checked all diodes
I've replaced the input power socket (intermittent contact)
I've replaced the PLCC 21-pin EPROM socket ( )
I've resoldered each and every pad in the board ( )

No luck so far. Always the same erratic behaviour. Sometimes it recovers with a Hard Reset of the CPU (U7, pin 4) only to hang again shortly after.

I have noticed two things:

- The 3.6V Zener goes much too hot for my tastes when fed with external power
- DAC testpoint ( above D7 LED) gives no DC reading when failing to boot.

¿Any ideas?

[pdman]

Bump

[beedoola]

Is there any other methods or areas to check out regarding the trouble shooting posted on the first page?

I checked D16, U14, U20, and U21 with all the voltages checking out. There is this white spot on U7, not sure if that is a manifestation of a failure or just paint/blotch of some sort..

[beedoola]

bump. please help 

[beedoola]

can someone give their voltages from the test points - from their working DL-4.

Mine are (in DC)

MCLK - 1.5v
LRCLK - 0.7-9v
SCLK - 0.4-6v
ADC - 3.1V but it drops down to 2 so and then back up
DAC - 0.0-1v, it gets cycling.

[beedoola]

so I can get it to power sometimes but it get stuck. You hear the relay click, the lights flash - first two LEDS and then the second two but gets stuck on the 3rd and 4th LEDs - they just stay lit.

[rockhorst]

Press the EPROM chip. It has a tendency to get loose from the constant pounding on the pedal

[beedoola]

Its pressed into the socket pretty good.. I also throughly cleaned the pin contacts on the socket and the chip.

Also, the power up issue and LED freeze occurs even without having a cable plugged into the Mono Input. And I have to wait about maybe 30 seconds or more before I can attempt to power it again. If I try to power it up again right after another power up - nothing happens. I know someone mentioned C40 is for the timing boot delay but I'm not sure if that would cause the issue.

Can anyone provide the test point voltages?

[beedoola]

is it odd that my DL-4 board is missing this transformer thing... My version is V1.3, so says the EPROM...

[beedoola]

anyone?

[beedoola]

can anyone share there readings from the test points? Mine are now:

MCLK - 1.590dc
LRCLK - 3.2dc
SCLK - 3.2dc
ADC - 3.2dc
DAC - 3.2dc

area around the diodes gets crazy hot.

[Processaurus]

can anyone share there readings from the test points? Mine are now:

MCLK - 1.590dc
LRCLK - 3.2dc
SCLK - 3.2dc
ADC - 3.2dc
DAC - 3.2dc

area around the diodes gets crazy hot.

MCLK, LRCLK, SCLK are test points for different clocks in the system, they are very fast square wave clocks to run the digital stuff, so they aren't a DC voltage.  You would need a scope to inspect them, unless your multimeter's AC setting measures waveforms up into the MHz.

Sorry your pedal stopped working, I banged my head against the wall for hours trying to get mine to work and gave up.  There just isn't enough documentation out there to debug the digital section.

[Swamp]

Press the EPROM chip. It has a tendency to get loose from the constant pounding on the pedal

You made my day bro!

Dl-4 completely dead. No voltages.
Changed all caps (100uf & 220uf) and diodes (2x 1N4007 & 3.6V zener), the voltages get right but pedal not working.
Press the Eprom and it back to life.

[mistahead]

OK - so we can possibly link in the technicians guide from the Apple II here... lift [pedal] up off hard surface around one foot, drop on surface to land square, if not resolved open casing of [pedal] and firmly press on all socket and slot housed components.

[beedoola]

Can someone help me out here. I got another dead DL-4 (I was able to sell my last dead one for what I paid for it broken, so I evened out).

D16 was reading open. I replaced D16 and D11 with 1N4001. I'm getting 9.3v at D16 and 4.6 at D11. I'm getting 2.2v at U14. At the voltages right for the diodes?

I had to replace D16 again as it fried up upon replacing it - this was before replacing D11.

I'm getting 4v on U20 and 3.2 on U21....

[mistahead]

So what you are just buying blown gear, fixing/reselling it and asking us to troubleshoot?

Good business model mate.