I filled one with a wire (legs leftovers from through hole parts) in the end..
as it was not possible to get the solder through by just soldering it..
I will do that now in general…
And yes.. the worst so far..
Ensoniq DP/4+ REPAIR (cap leakage, corrosion)
- Thread starter Script
- Start date
Help Support GroupDIY Audio Forum:
as it was not possible to get the solder through by just soldering it..
I will do that now in general…
And yes.. the worst so far..
Input section Part 2
Looked worse as well. But in the end it came out pretty nice. I also completely resoldered all connectionholes .. It worked out better than in the first part.
All parts are cleaned now and ready to get repopulated onto the board
Looked worse as well. But in the end it came out pretty nice. I also completely resoldered all connectionholes .. It worked out better than in the first part.
All parts are cleaned now and ready to get repopulated onto the board
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Should be easy enough in non-populated state to check whether all contact holes connect properly. If they don't, easier to fix now. Also easier to clean the board in this state from electrolyte residue. Maybe also check for (capacitive) coupling of adjacent traces, as suggested somewhere above.
I should do all that with my Unit A.
I like the tray thing you use there.
I should do all that with my Unit A.
I like the tray thing you use there.
Yes, this is the moment for those things to do properly.. There are still some black spotted traces I will take care of. Also some black krusty leftovers… Sometimes with the fluxpen and isopropyl is not enough.. the sharp tweezer is helpfull then…
BTW: If the pads are krusty black.. it‘s better to use the fine tweezer to scratch it off while the pad is COLD..
I don‘t use solderwick anymore.. too much physical force combined with the heat is too much for the solderpads. They come off easier.
I just use the fluxpen, soler, iso… and for the krust the sharp fine tweezers..
If you give them pads a nice solderbath and treat them gently without force, they can take a lot of heat..
The three pads just came off because I tried to scratch off the black krust with the iron
TBC
Hello! I have a DP4+ that I bought in 1997. It was in storage for probably around 20 years. I'm trying to figure out if I need to recap this unit. I've replaced the battery and this unit works perfectly. The only issue is a noise coming from the power supply, but it's not in the signal path, its a noise that can be heard coming from the unit itself. I've taken some pictures and all the caps look fine. Any suggestions would be greatly appreciated.
Thanks,
J
Thanks,
J
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Be glad it still works
Recap needed 100%
I have a unit at the moment as well that also still works. But it also has some black traces already
I'm inclined to say it needs a recap -- sooner or later.
I think there was an issue with the electrolyte formula of those particular early-generation caps used in those units back then -- not sure how they age under no-use.
Visual inspection with magnifying glass.. Any kind of discoloration (trace and on board), corrosion, gunk or the tiniest drop of transparent liquid on the PCB point to a recap. So does a sluggishly reacting display (3.3uf power cap on front assembly board).
Could also measure one cap each of the three different value caps. But would need to take them off the board for that.
Or just use it for a while, but be sure to stop using it immediately and start recapping at first symptom of failure (overload LEDs turning on when no signal present = surely leaked and/or caps dried out).
Thanks for the input! I've never done work with SMD components before so I'm gonna try and find a circuit to practice on before I attempt this. From everything I've read on this thread, it seems like a much easier job when done before the caps start leaking.
Yes, most definitely. Easier with the right tools. This board is little forgiving (leakage and maltreatment).
When disassembling, do NOT pull on the cables of the connectors. Try to leverage upward with a scribe or thin screwdriver.
Wiggle connector until there's a tiny gap to insert scribe etc like so:
When disassembling, do NOT pull on the cables of the connectors. Try to leverage upward with a scribe or thin screwdriver.
Wiggle connector until there's a tiny gap to insert scribe etc like so:
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Last edited:
Thanks for the tip Script, I did have a lot of trouble grabbing hold of those ribbon connectors, found it almost impossible. I did in fact have to pull on the ribbon itself but I wont do that again. Are you guys using hot air rework stations for the SMD stuff or a soldering iron?
For the electrolytic caps it‘s not recommended to use the hot air station. I would just use one of the methods of this guy here in the video..
On my latest units I used the pliers twist the cap method.. What he doesn‘t mention in the video is to put some pressure towards the pcb while you twist off the caps.. to avoid harming the solderpads underneath.
Worked pretty well on my last units.
Practice on a scrap board before.. to get familiar with this method.
Much recommendet channel anyways
I would replace the smd elcos with normal trough hole caps.. like in the video that was posted before.
Awesome man, thanks for the info! This is super helpful. I really appreciate it guys!
A little report from the cheap but savaged Unit… : Analog board on the way… Nearly cleaned all elca areas … overworked some black traces .. replaced some broken ceramic caps as well.. and some diodes… Looking forward to put back the big parts onto the pcb
I will put the big Sony ICs onto sockets..
And fingers crossed some signal is getting trough
I will put the big Sony ICs onto sockets..
And fingers crossed some signal is getting trough
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Obsoletemachines
Member
hi, working a pretty clean DP4+ with bad dc offset recently. I know this is low-use DP4+ as there isnt a large amount of flux deposited on the underside of the lid. Also there isn't much evidence of capacitor leakage. I have worked on and fixed around 20 DP4+s so i know them pretty well, the variations the revisions et cetra.
So, on this clean looking DP4+ the caps have leaked, particularly near the input section where 22uf are located because there is DC here where there shouldn't be any. I noticed fine mist oil like liquid and look closely at the legs of the 4565 op amp for 3/4ch (3rd photo) and the 4053.
If the 4565s are likely damaged. I have scoped them before and noticed 'bell-like' bias where there should not be. Change for 4565MD 'low-noise' variants Nippon Japan Radio
ALSO: The cap at C238 gets worked right to the limit, if it fails it can leak and damage the 74hc86, which effects TTL to the TDA1541 and which can cause all kinds of problems which manifest as 'bad dc offset'. you can see this with a scope. The leakage from c238 can also eat vies that send the 35khz chop all the way across to the chop op amp circuit that feeds the CX20018 via 4053 which again gives you 'Bad DC offset' - basically bad dc offset means the resulting s/h is too high, and not inverted.
So, on this clean looking DP4+ the caps have leaked, particularly near the input section where 22uf are located because there is DC here where there shouldn't be any. I noticed fine mist oil like liquid and look closely at the legs of the 4565 op amp for 3/4ch (3rd photo) and the 4053.
If the 4565s are likely damaged. I have scoped them before and noticed 'bell-like' bias where there should not be. Change for 4565MD 'low-noise' variants Nippon Japan Radio
ALSO: The cap at C238 gets worked right to the limit, if it fails it can leak and damage the 74hc86, which effects TTL to the TDA1541 and which can cause all kinds of problems which manifest as 'bad dc offset'. you can see this with a scope. The leakage from c238 can also eat vies that send the 35khz chop all the way across to the chop op amp circuit that feeds the CX20018 via 4053 which again gives you 'Bad DC offset' - basically bad dc offset means the resulting s/h is too high, and not inverted.
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Obsoletemachines
Member
here is my personal DP4+
Triple height heatsinks for regulators, although if i did this again i'd replace the 5v regulator for traco switch mode drop-ins.
I used nichicon fine gold caps which do open up the sound.
Also if you have cyclical noise on the outputs that sounds like radio-interference sweeping, replace the J110 in the JFET mute circuit. There is an intermediate failure mode where this occurs. Full failure is exhibited with low-output and ground noise.
Triple height heatsinks for regulators, although if i did this again i'd replace the 5v regulator for traco switch mode drop-ins.
I used nichicon fine gold caps which do open up the sound.
Also if you have cyclical noise on the outputs that sounds like radio-interference sweeping, replace the J110 in the JFET mute circuit. There is an intermediate failure mode where this occurs. Full failure is exhibited with low-output and ground noise.
I would recommend to check and compare the signals on the polystyrene caps.. My DC offset came from that area.
Also take care about the typical black traces in the inputsection
How did you insert them ? Leads soldered to pads?
I will try to use the Pan FGs as well
Did you leave the 3.3yF caps (also on the digital board)? Or did you just swap them 1:1 through smd ones ?
I would like to see more details of the parts you changed.
Did you also recap the PSU?
And what powerregulators would you use in detail? Just the 5V or also the 15v?
Obsoletemachines
Member
- i used long life Panasonic some non-audio decouple capacitors
- i used long life 3.3uf, some do fail. I have had one fail on the PSU board while i have been using the unit - you get this characteristic fish oil smell.
- I recapped the PSU with TDK EPCOS long life 105C 8000-10000 mtbf low ESR
- I did change some regulators but you don't need to. if you do, you must track down DG 'double gauge' so they fit snug with the heatsinks.
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