Digital Reverb Troubleshooting

[emejia]

I am the original owner of a DSL15C with digital reverb. The amp probably has less than 10 hours total on it, but it is out of the warranty. The reverb has gone out - completely silent. I have
- Removed the reverb circuit board, cleaned the contacts and re-seated
- Plugged in the footswitch and repeatedly tried to switch the reverb "on" just in case the switch was stuck in the "off" condition
- Tapped around on the board components to see if there were any loose solder joints
- Cleaned and reseated the wires to the reverb switch (coming off the foot pedal jack to the board beside the reverb circuit)
None of this has made any difference. So, I was hoping for a few suggestions:
- Would cleaning the reverb pot help? It's not scratchy, just no reverb at all.
- Any other suggestions on troubleshooting?
- Any place that sells replacement boards or repairs and returns them? Our local amp tech only works on P2P amps.
Thanks in advance for the suggestions and advice. BTW - I know I could get a pedal, etc.

 

[Jon Snell]

Not a lot to be done with those if you have checked for power supply issues; 3v3 on pin 11 and 5v on pin 8.
Does the oscillator run on the effects board?
Has the AT2313 got supply and are the pins showing signs of life? Check with your oscilloscope.

 

[emejia]

Not a lot to be done with those if you have checked for power supply issues; 3v3 on pin 11 and 5v on pin 8.
Does the oscillator run on the effects board?
Has the AT2313 got supply and are the pins showing signs of life? Check with your oscilloscope.

Thanks for the detailed response, a bit beyond my abilities so may be time for a new amp - gives me a good excuse to buy one.

 

[TassieViking]

I have seen a post a few years ago where the digital reverb boards would go regularly, someone wrote how he pre-heated his oven and stuck his effects PCB in to a hot oven for a short while and it fixed it.
The moral was that the solder was crap on those boards and the oven re-flowed the solder on the PCB and fixed the bad connection in the effect board.
I have no idea how hot the oven should be or how long to leave it in for but you might find the article with lots of searching.
I think I found it under a "Fender effect PCB" search

 

[Jon Snell]

I have seen a post a few years ago where the digital reverb boards would go regularly, someone wrote how he pre-heated his oven and stuck his effects PCB in to a hot oven for a short while and it fixed it.
The moral was that the solder was crap on those boards and the oven re-flowed the solder on the PCB and fixed the bad connection in the effect board.
I have no idea how hot the oven should be or how long to leave it in for but you might find the article with lots of searching.
I think I found it under a "Fender effect PCB" search

(Mainly used for Ball Gate Array LSI components that were soldered with lead free solder. It reduces the tin whiskers back to the solder land).

Also not the correct way to reflow solder on a standard component.

An extractor fan must be used.
Apply plenty of flux on the solder side of the board, warm the complete board up to 110C and with a hot air reflow machine, go over the solder joints, pausing for no more than 10 Seconds once the solder melts.
Set the air temperature to 200°C moderate flow. Any hotter and the board will be damaged. Heat for more than 15 Seconds after solder melts, may damage the components.
Let the board cool naturally to avoid stressing the components.

I use my trusty computer temperature controlled Infra Red IR6500 rework station for all PCB reworking.

 

[PelliX]

I have seen a post a few years ago where the digital reverb boards would go regularly, someone wrote how he pre-heated his oven and stuck his effects PCB in to a hot oven for a short while and it fixed it.

Oh this brings back memories of the 'towel trick' for 'reflowing' BGA's on Xbox's and co. TL;DR: Do not do this, it won't work (or work reliably) and it will likely damage things.

The moral was that the solder was crap on those boards and the oven re-flowed the solder on the PCB and fixed the bad connection in the effect board.

May be crap, but you're not really reflowing lead-free solder at those temps. Effectively it forces the material to expand, thus often "improving" the connections of a BGA for a while. If at all.

As Jon suggests, a heating plate and hot air station will do this, though I tend to go with the air a bit hotter. Depends on the components, component density, size of the solderjoints, solder used, etc. Not sure if an extractor fan is really required, but it won't hurt. Incidentally, there's a common misconception about solder fumes; many people assume you're breathing in lead (in the case of proper leaded solder), which is incorrect. You would need temperatures well beyond any soldering iron to turn lead to gas. The smoke is actually rosin flux evaporating. No, it's not healthy, but it's far less hazardous than consuming lead.

 

[TassieViking]

I know this is not the correct way, but it worked on several PCB's that the author of the article tried it on.
I think he had the oven set somewhere between 250 to 300 Celsius when he placed the effect PCB's in the oven, and he only left them in for a short time.( He used aluminium foil under the boards cause it can get messy )
He was going to throw the amps out so he thought what the heck, give it a try.

I think they might have used lead free solder when they made the boards and that crap is....well crap.
It was a fair while since I saw that article and it saved those amps from the scrap bin, so why not give it a shot ??
The proper SMD hot air guns and stuff can get expensive, especially if you are never going to use them again.
I just use a very fine tip myself when I play with any SMD components

 

[PelliX]

I think they might have used lead free solder when they made the boards and that crap is....well crap.

Did the amp say RoHS? Then it's probably lead-free.

The proper SMD hot air guns and stuff can get expensive, especially if you are never going to use them again.

Well, a heating plate can run up a bit, depending on what you want and how nice of course. Nothing prevents you from using another heat source for the preheating, though. A hot air station like the Atten 858D+ costs you a few tenners on fleabay. I mean, while the calibration may be a bit off, hot air is hot air... It's my most used hot air station, had it for over 10 years and never had to service it yet.

I just use a very fine tip myself when I play with any SMD components

Ha, yeah, a little flux and an iron can get you a long way

Still, if you're going to do it, do it right - IMHO. After all, imagine you pseudo-fix it and it goes faulty again. That would annoy me - being aware I'd bodged it and that's why it failed again, you know? It's your choice at the end of the day, of course.

 

[emejia]

You guys are way beyond my skill level, and apparently beyond the skill level of any amp techs nearby. So, I sent Marshall a message asking if I could buy a board from them. Nope, they only sell to authorized service centers. I asked for the nearest one of those, twice, and crickets - no response. A shame really, I had great service from Marshall when I took my UK purchased DSL 50 to Bletchley for a voltage conversion before returning to the states. Great service, good folks, but not much help on this amp. I figure the reverb board cost them all of 5 dollars to source from Vietnam.

 

[Kuga]

I know same thing can happen on a VM2466. You turn on the amp and no reverb. To solve It you need do a reset on reverb board. You need to power off amp when It is in normal working condition. Exemple: power switch on and standby switch off like when you are playing it normally. Then just turn off the power switch. I hope you can solve It.

 

[emejia]

I know same thing can happen on a VM2466. You turn on the amp and no reverb. To solve It you need do a reset on reverb board. You need to power off amp when It is in normal working condition. Exemple: power switch on and standby switch off like when you are playing it normally. Then just turn off the power switch. I hope you can solve It.

Thanks for the tip, unfortunately this amp only has one switch (no standby), but I do have a VM2266 that I can use that for if the reverb ever goes out.

 

[Kuga]

Thanks for the tip, unfortunately this amp only has one switch (no standby), but I do have a VM2266 that I can use that for if the reverb ever goes out.

I don't know If could work but usually digital reverb works at 5vdc maybe If you take out 5Vdc on the reverb when the amp it's on could do a reset on digital reverb. I don't know If it's easy to do. Also I would try power on the amp without HT fuse then turn off and then reinstall HT fuse to see If digital reverb could works. I think this digital reverb just It gets blocked. Just I try to help you maybe digital reverb it's dead but It's so rare what happened.

Once I connected an attenuator backwards on my VM2466. I used It at full volume just a few minutes then blow out power tubes, resistors, fx loop transistors,... The digital reverb every 5 times I used It on three times doesn't works. Mr Steve Dawson explained on an other forum how restore digital reverb on the Vintage Modern amps. I was able fix the amp but I bought a new digital reverb.

I hope you can solve It.