Thoughts on a dead Line 6 DL4?

[kwijibo]

I'm also having DL-4 trouble. 3.3V, 6.5V, 5V and -5V all measure OK and don't shown any ripple on a scope. I also see a 12MHz clock on the MCLK test point. When I plug a lead into the input the unit usually doesn't start up, and maybe 1 in 10 times it will switch on some LEDs and then freeze. Very occasionally I have heard the relays click as well. I'm starting to suspect the EPROM, I'm currently waiting for a PLCC adapter so I can dump it and see if it looks OK. In the meantime, does any have any other suggestions? Is there a known working dump of the EPROM out there that I could use to bring this back to life?

[beedoola]

I got another Dl-4 recently for $20.

This one isn't dead, it powers up and passes the dry signal when in True-Bypass mode, but when an effect is engaged, I get white noise. If I back the mix off completely, Everything is fine.

What I've done so far:

Both reset types: A & D switches (factory reset), A & C (bypass type) - the noise is preset in the Spill over bypass but not True-Bypass.

Re-seated the EPROM chip - cleaned the socket and chip pins with Deoxit.

Cleaned the Input jacks with Deoxit.

Any suggestions? Could this be a bad eprom chip? I thought I recalled reading accounts by people saying that if the oscillating feedback is to harsh it can damage something.

[toneman]

did U check all the power supply voltages??
both source AND distination??

here's a new link to the power supply schematic:

http://aronnelson.com/gallery/main.php/v/MrHuge/Line+6/DL4_ps.jpg.html?g2_imageViewsIndex=1


look over the solder side of the pcb for cold solder joints, especially around any sockets.

afn

[beedoola]

did U check all the power supply voltages??
both source AND distination??

here's a new link to the power supply schematic:

http://aronnelson.com/gallery/main.php/v/MrHuge/Line+6/DL4_ps.jpg.html?g2_imageViewsIndex=1


look over the solder side of the pcb for cold solder joints, especially around any sockets.

afn

voltages check out. I desoldered and resoldered the EPROM and Relays, no change.

So when the Mix is down, clean signal is fine.

Also, in Sweep mode, the noise drives the LFO. Does that possibly help in locating where the issue is?

[beedoola]

bump

[beedoola]

Do you need 6.6v at U20? I replaced the U14 cause it was dead - not putting out 3.3v, but now it is. I'm getting 6V on pin 8 of U20, 5V at U21.

I got the DL-4 to power once, the bypass worked but no delay/effect. Then it stopped working. I got it to boot half way and then it stopped - doing the hard reset.

[beatnik]

thanks for all the information on this thread i've managed to fix a dead DL-4 i got off ebay

with batteries, all the voltages are fine and delay sounding great

i still have some problem using an external 9V AC power supply (2000mA)

at 6V DC point I have about 14VDC  instead. I haven't tried if the delay works because rating for the MAX887 is maximum 11V so I don't want to burn something again.

if i lift D11 cathode off the pcb and measure the voltage i got about 5.5V DC which should be fine

if the diode is put back on the circuit the voltage rises to 14V DC

i am wondering what is the problem here. any help is highly appreciated

power supply schematic

http://aronnelson.com/gallery/main.php/v/MrHuge/Line+6/DL4_ps.jpg.html?g2_imageViewsIndex=1

[dustartist]

I'm working on a dead DL4 as well. What parts did you replace?

[phunksta]

Attempt at reviving a dead thread....
So I traded my micro chorus and phase45 script for an mm4.  The guy gave me the ps and the pedal for it, but said the power supply doesn't work but it works fine off batteries.  I got it home plugged it in and he was correct.

After doing some diagnosing and with much help to MrHuge and Tombeau's posts in this thread, I was able to to determine that the zener was bad, as well as the MAX660.

I've now replaced the zener and the two rectifier diodes, the 1000uF cap and the Max660.  But am getting bizarre readings...

The 6VDC is reading as 11VDC, and the 6.6Vdc of the output of the max660 is reading 2.45VDC.  However I am getting the 3.3 VDC out of the MAX887.  Very strange.  I would have to guess that something is amiss in the rectification circuit still and i must have damaged the MAX660 when replacing it (i dont have a HA rework station so am using the copper wire/soldering iron trick to remove the smd components

Other than replacing the zener and MAX660 again...any thoughts on what could be wrong?  Possibly C59 and/or C48?

The MAX660 says it's absolute maximum supply voltage can be 6VDC.  which is odd because its supplied 6.6V according to the DL4 PS schematic.

At the end of the day I might just have to scope all the voltages to check for ripple/etc.

Schematic: http://aronnelson.com/gallery/main.php/v/MrHuge/Line+6/DL4_ps.jpg.html?g2_imageViewsIndex=1
MAX660 DataSheet: http://www.ti.com/lit/ds/symlink/max660.pdf

[prebblet]

Thought Id add my experiences to the list.

Just had 4 DL4s in for repair. 2 were easy fixes. The other 2 as below

1, MAX887 had failed as described by others.

2. All the power supply points were as expected, but the unit would not power up. After searching around the circuit I discovered that the EEPROM was not working. I removed the IC then reinserted it. It then burst into life. I assume a failed connection on the EERPOM socket. I sprayed the connector with contact cleaner and reassemble it.

So may be worth a try to those that have a non powering DL4...

[robmay]

I'll add my woes to the list, too... Two DL4s, both dead.

One of them after a bunch of Deoxit appeared to be stuck on one preset, and refused to pass any audio, and after sitting testing different points for voltage mysteriously started working again... Make sure that when you use Deoxit, you follow it up with some canned air or a little rub with a cloth to really clean it up. Seems it just needed a jolt somewhere and it was fine.

Second DL4, after some Deoxit, started passing signal in bypass mode and showing proper LEDs and control (as in the presets would load, and delay time knob changed the 4th LED rate), but passed zero signal in effect mode. After measuring voltages on the working DL4, I figured out that the MAX660 is bad, as I get great voltages up until then (which is I imagine how I'm getting what looks like proper control over no actual signal effecting), but after that where I should have 6.6V and 5V around the U21 transistor, I have ~2.5V and ~0.8V respectively. Ordered a couple MAX660 to try the swap, hoping that works out.

To those that find the power diodes heating up or hot... The working DL4 I have does this too. I don't think it's a problem necessarily, though I'm sure it makes them more prone to fail. Make sure they're among the first things you check, though I'm sure if you're reading this far you've already checked them. On that note, can anyone give any advice as to alternates/replacements that would be more heat-resistant or reliable, yet still do the same function?

Other than that, if anyone needs any voltage points tested that aren't on Aron's handy DL4 PS schematic, give me a shout either here or PM... happy to help builders in need.

[duck_arse]

these power diodes - what type number are they? you can provide diodes with heatsinks just by standing them on longer than normal legs, so they sit 10mm or so above the board.

[rv456]

does any of them work with batteries?..
I used to work as repairman for the scandinavian Line-6 distrubitures, so I think I can help...due to signed non-disclosure agreements, I cant send you copies of the schematics, but i can guide you through...
..so follow me now...
...first thing to do. Plug a monoplug into the mono input, press footswitches 1 and 4 down and apply power. dont let go of the switches for at least 5 seconds. if nothing happens, its time to open up.

from the AC-in, power goes throu a 3,6v Zener ( D16 ) then on through D11. the 3,6v zener are known to fail, but doesnt affect battery operation.
after D11, power meets up with the battery in... next comes U14, a little 8-pin ( SMD ) MAX887. this one takes things down to 3,3volts ( mesure pin7/ signalground ). if you have 3,3volt on pin7, go on to U20.
U20 is a MAX660 wich is a voltage doubler. check the DC voltage on pin1 ( or 8, they are tied together ). if you have 6,6volt here, next in line is a tiny thing called LM3480 ( U21) this one will even out things for the digital domain to 5 Volt...if you havnt found fault yet, and reset doesnt work..dont bother...

..so the most likely suspects are
1: 3,6v Zener ( D16 )
2: MAX887 ( U14 )
3: MAX660 ( U20 )
4: LM3480 ( U21 )

hope this help...

johan

Hi Johan, thanks for the info.  I have followed your steps and have found that the MAX887 is giving out 5V instead of 3.3V.  Any idea what is causing the fault?  I have cleaned the board and reflowed some joints and it fixes the problem briefly, before something goes and it doesn't power on.  Thanks

[drummer4gc]

I've used this thread over the last few years to fix a couple Line 6 modelers, and I was hoping someone might be able to help me understand one particular aspect of the power section a bit better - what's the deal with powering with 9VAC vs 9VDC? 9VAC is recommended, I've read that 9VDC works as long as voltage polarity is reversed from the center negative we typically used, but I've been able to power mine up using both polarities without issue. Can anyone help me understand why?

Also, I just fixed another one by replacing the D16 zener (using part number 1n4729), and the new one is getting crazy hot (tried both polarities 9VDC), as reported above. Based on the schematic, is that to be expected? Possibly a design flaw as the zeners are known to fail, and I can't imagine the heat helps?

For reference:

[kirbysnacks]

Also, I just fixed another one by replacing the D16 zener (using part number 1n4729), and the new one is getting crazy hot (tried both polarities 9VDC), as reported above. Based on the schematic, is that to be expected? Possibly a design flaw as the zeners are known to fail, and I can't imagine the heat helps?

I went down the same rabbit hole this week (in the hopes of ordering all my replacement parts from Mouser) and after much hemming and hawing I opted to order part number 2EZ3.6D5 instead from DigiKey since it's rated for 2w. Reading your post now I'm thinking I made the right call! I'll post an update when the parts arrive.

[kirbysnacks]

And for reference, here are the borked components I'm replacing. Seems like a trend with these pedals!

1 x 1000uf 16v Radial 1000 uF 20 % 16 VDC Aluminum Electrolytic Capacitor
1 x 100uf 25v Radial 100 uF 20 % 25 VDC Aluminum Electrolytic Capacitor
1 x Texas Instruments LM3480 Series 5 V LDO Voltage Regulator
1 x Maxim Integrated MAX887HESA Voltage Regulator
1 x Maxim Integrated MAX660CSA Voltage Regulator
1 x Microsemi #2EZ3.6D5 3.6v Zener Diode, DL-41