Repairing an SP404 need help

[clean_and_humble]

Hey
I recently got a broken SP404 from a guy who plugged in the wrong power supply. After he did that the unit does not power on. Sounded like a blown fuse to me. So I opened it up and found 3 surface mount fuses burnt and one chip with a little melt on the center of it. Here are some photos of my findings






My question is
1. where can I order these 3 fuses ?
2. how do I figure out the value fuses I need?
3. Does that chip look effected ?

My opinion is that the fuse just has surface damage. I am thinking if I replace these 3 fuses I will get this working again.

Thoughts ?

[Jim Williams]

It's probably land fill material. Besides the parts, the surface mount pcb pads are cooked, good luck restoring those. Besides, I see additional damage, like that large IC in the center, it's fried. If this is a four layer pcb, consider the inner layers to be damaged too.

Like the Gambler says:

"You got to know when to hold 'um, know when to fold 'um".

[The Scum]

Unless you're a surface-mount rework ace, this is going to be a tough repair. I don't even have the tools properly replace that scorched chip. I could probaqbly get it loose, but would probably wreak further havok in the process.

There's a good possibility that there is damage beyond what's visible.

You call Roland, credit card in hand, and ask them two things:
1> Can you buy the service manual? That's the key you'll need to dig any deeper.
2> Can you buy a new main board assembly? That's the level at which their service centers operate.

The cost of those two items probably trumps a working used unit.

They used to be very cooperative with independent techs who called them up. I don't know if you have to be "in-network" or not these days.

[clean_and_humble]

The electronic DIYers on this forum are a little black cloud over their heads huh?
come to think of it every topic on this board needs a ray of PMA
perhaps it comes from the leader grumpy Larry but in any case much like
an Italian American family I know you all are looking out for me and mean well and tape op is still one of the best mags out about this stuff so.......

Let me first say that I do have some of the money puzzle you presented sussed
the manual I was able to download for free as a PDF online so that illiminates that cost and search in the puzzle. According to techs over on the EEV blog forum the 4 parts shown that are damaged will be well under 50 bucks

Here is what the verdict was over there
input voltage regulators are the 3 fried parts pictured
and the chip is the boards main Ram
those parts are cheap as far as the opinions on that blog

It does appear that the other chips like the EEPROM have survived but the parts I am looking for now that might be fried are the pads like the lad here says
and maybe the 3v3 was effected .....


I do not think I will call Roland I have in the past and they are purpponents of the new method of "why fix old when you can BUY BUY BUY! BUY OUR NEW PRODUCT ! IT WORKS SHITTIER THAN THE LAST MODEL BUT COSTS MORE ! BUY ITS GOOD FOR YOU! IT WILL MAKE YOU AS FAMOUS AS JAY Z BUY DAMN YOU!

Anyhow ....
If it does turn out that a new board is the solution yeah I will buy a used one
womp womp
But know that I bought this unit to challenge myself and learn
so the idea of desoldering surface mount stuff yes I agree with you seems fatal however nothing is imposible with PMA right Larry Jr ?

A little flux
a decent Iron (which I own)
and a really good how to video
worth a shot right ?

Only thing that can deter me is if
I reach a part that will bring my costs over 100 bucks
so far a RAM chip that I can probably find in a junked DVD recorder
and 3 voltage regulators and perhaps another component I doubt will cost
exorbitant amount of money .........
However frying the board in the process of learning
Yeah I dig you
and that is realistic however
I had a shop teacher in 7th grade that self proclaimed himself
"A Realist" before every class and needless to say no one but me
who chose to ignore his vibe was excited about learning about
California job cases and ancient stuff like that


Mad respect and love for the Italian American style love yall pump out
it does have a pinch of I know better than you hipster salt though but hey
What braciole does not need a little spice right

I will keep yall posted

PS for reference sake and other googling folks in the same repair situation as me
here is the link to get the service manual
http://elektrotanya.com/roland_sp404.pdf/download.html

[Jim Williams]

Haven't a clue what you're saying, I don't speak Ital-glish. I'm from the west coast so I'm somewhat of a foreigner to that urban east coast stuff.

Having seen plenty of fried, densly packed surface mount audio junk you too are finding out why the manufacturers won't repair it either. This is the nature of low cost, automated surface mount construction: It's far easier and less costly to replace the pcb than to do any repairs on it.

Even if you replace those regulators, you may find out what caused them to fail after watching them burn up again. This is because there are damaged parts downstream. Until all of those are sussed out and replaced first you will just watch it let the smoke out again.

If you want to learn how to fix/repair/study audio electronics, start at the beginning with simple through hole designs, not with computer style pcb's.

If you, like me are uncomfortable buying disposible low quality audio surface mount gear, invest in gear that will last and that can be repaired.

[kslight]

The electronic DIYers on this forum are a little black cloud over their heads huh?
come to think of it every topic on this board needs a ray of PMA
perhaps it comes from the leader grumpy Larry but in any case much like
an Italian American family I know you all are looking out for me and mean well and tape op is still one of the best mags out about this stuff so.......

Any and all potential help goes in the toilet.

[chris harris]

Yep. Good luck, Mr. Humble (LOL).

[E-money]

The only learning experience to be gained here is you'll quickly learn that you've bitten off way more than you can chew. Getting a fried chip out is damn near impossible without the proper tools, you'll end up destroying some of the traces trying to extract that thing and you're going to get frustrated and you're going to waste hours of your time.
Even if you can get it out w/o destroying the circuit board, getting the new one in without overheating it will be damn near impossible. And as Jim Williams stated, even if somehow you're able to replace all the parts that are bad, you've not determined what caused them to go bad. The second you apply power, you could easily end up frying them all again.
Do yourself a favor and find an easier project to get your feet wet with. Build a stompbox, there are plenty of designs and kits online.

[kayagum]

Surface mount electronics = planned obsolescence = disposable electronics

[clean_and_humble]

Here is what I decided
you guys are correct

I am not going to try to fix it
However being that its junk anyway
I am going to at the very least try and desolder the part for practice
if I destroy it really does not matter at this point

Maybe I will look into how much a new board costs
I can surely use this as an opportunity to practice using my scope
and meter to try and discover what went wrong
Thank you all for being so caring in your look down your noses type way
I love the guy who criticized my humbleness at least Jim has a sense of humor
and even if in a very californian way he try's to show me
the error of my "NY Italian ways" by saying what does race got to do with it
Nam yo ren gya cho Tina
Ike won't hit yall no mo

I am gonna go read the NY Times now and put on sandals
right after I bow before a picture of Larry Crane
someday I hope to grow up and be so cool and give people the business
in this really formal education manner where no one thinks
its rude or out of line and I just tell people who were educated differently
by the old way of trial and error and make do with what you have
That they need to check themselves without ever checking my own self

Big world yall
Lots of different walks of life in it
Not everyone is from california

Anyhow
Love is love
and I feel like I can give you all the business in return !


Great thing is you all really are nice
because you did give your honest advice and for that I am thankful

Anyone how wants to spar with words come to Brooklyn
If you think I am a moron I will show you some real morons

Peace Love Unity and having fun (with useless attempts at electronic fails that lead to learning)

[clean_and_humble]

The only learning experience to be gained here is you'll quickly learn that you've bitten off way more than you can chew. Getting a fried chip out is damn near impossible without the proper tools, you'll end up destroying some of the traces trying to extract that thing and you're going to get frustrated and you're going to waste hours of your time.
Even if you can get it out w/o destroying the circuit board, getting the new one in without overheating it will be damn near impossible. And as Jim Williams stated, even if somehow you're able to replace all the parts that are bad, you've not determined what caused them to go bad. The second you apply power, you could easily end up frying them all again.
Do yourself a favor and find an easier project to get your feet wet with. Build a stompbox, there are plenty of designs and kits online.

Thanks E money for being real and in a humble way
I bit off more than I could chew because I thought it would be a simple blown fuse
based off of another piece of gear I fixed that had a similar problem. Dude plugged it into a 220 and I opened that unit up and boom blown fuse replaced fuse and it worked. Learned the hard way but still gonna try and learn from it! Respect for the love

[E-money]

Thanks E money for being real and in a humble way
I bit off more than I could chew because I thought it would be a simple blown fuse
based off of another piece of gear I fixed that had a similar problem. Dude plugged it into a 220 and I opened that unit up and boom blown fuse replaced fuse and it worked. Learned the hard way but still gonna try and learn from it! Respect for the love

No problem, hate to see you go down a path that is just going to just drive you mad. Sometimes you get lucky, I was given an Ampeg V5 that only needed a new fuse. Older stuff tends to easier to repair, surface mount stuff is the bane of every decent electronics tech.

Finally, never take Jim Williams posts lightly, the guy is brilliant. If I started now and spent 8 hours a day learning electronics, I would never reach his level. He's one of the truly great assets that you will find on the Internet. I enjoy reading Jim's posts the way normal folks enjoy reading a great novel.

[clean_and_humble]

Thanks E money for being real and in a humble way
I bit off more than I could chew because I thought it would be a simple blown fuse
based off of another piece of gear I fixed that had a similar problem. Dude plugged it into a 220 and I opened that unit up and boom blown fuse replaced fuse and it worked. Learned the hard way but still gonna try and learn from it! Respect for the love

No problem, hate to see you go down a path that is just going to just drive you mad. Sometimes you get lucky, I was given an Ampeg V5 that only needed a new fuse. Older stuff tends to easier to repair, surface mount stuff is the bane of every decent electronics tech.

Finally, never take Jim Williams posts lightly, the guy is brilliant. If I started now and spent 8 hours a day learning electronics, I would never reach his level. He's one of the truly great assets that you will find on the Internet. I enjoy reading Jim's posts the way normal folks enjoy reading a great novel.

I am down with Jim's advice too
plus he has a sense of humor even if I think I got too NY Italian on him
There is a certain vibe around the Tape Op world
even at the AES table there is an energy that eminates from the table
that assumes too many things about too many people
Look I know most of the people who screwed up music and the world for that matter are the ridiculous Guidos (and that is Guido's in all cultures not just italians)
Who put lights on things that do not need them like audio gear, motorcycles and chairs but that does not mean if someone talks like those same morons
he is recording his music on the newest latest digital piece of shit....

I repaired a Tascam 80-8 1/2" with two fuses that cost me a dollar !
great day in my workbenches history

So I got the Madlib bug and wanted to start using a SP404 combined with my still working SP202 and I ran out and found a broke one on CL hoping I would not have to spend 400 bucks for this piece of shit that is not going to sound as good as my tape machines. Kill me !

It's not like I am going to make Trance with the f'in thing!

[The Scum]

So you wanna remove that RAM? There are several approaches:

a> Get an Exacto knife with a #18 blade. Chop off all of the legs, and remove the body of the chip. Then go in with a soldering iron and tweezers, and pluck off each leg, one by one.

(voice of experience: the exacto blade cut more than just the legs)

b> Use a heat gun and a dental pick. Heat the chip and gently pry it up with the pick. After about a minute, it'll just pop off.

(voice of experience: when the solder on the chip came loose, so did a bunch of other things)

The right tool for the job is actually somewhat like that. A hot air rework rig uses nozzles that match the chip footprint, and direct hot air onto the legs, so they come free without loosening anything else.

When you do manage to get this guy working by component-level repair, I know areospace companies that would love to hire people with skills like that.

Another positive note: Roland probably build the whole thing with less than $100 in parts (parts cost of 1/5 retail price is a reasonable margin). So your ceiling isn't too far out of line...even though you aren't buying 10,000 parts at wholesale prices.

[Jim Williams]

If you want to play around in there you can try a couple of things. You don't have anything to loose so it's low risk.

First, check the power rails with a continuity meter. Set it to low ohms and measure, If you find a short, that means a new reg will also fry quickly. Remove the large fried IC chip. You can cut the leads with a super tiny clipper or get some Chip-Quick solder and heat both sides until it comes loose. That special solder melts at a much lower temperature so ajacent parts don't all float away which can happen with hot air removal systems.

If you manage to cut the leads and remove the chip body you can use a Hakko 808 de-soldering tool with the larger 1.8 mill tip to heat and suck the pins off the pads. That leaves the pads flat and clean for the replacement chip.

Then re-measure the power rail feeds and check for shorts. If gone you may be ready for new regulator chips. You can also use standard through hole TO-220 sized regulator chips and connect wires from the pads to the chip. Then mount it with an insulator pad to the rear chassis to dissapate the heat. If the pads are gone, look down/upstream for fresh pads to solder to. Regulators are simple, in, out and reference pins.

If you get it working, consider a career as a bench tech.