Delay Project That'll Fit In A Boss Enclosure

[toomanypies]

I have here a Boss DD-3B. It's only about 8-10 years old. There is no signal from the effected output regardless of whether the effect is on or off. The LED comes on. There is signal from the direct out. As indicated in the capture below, I only have 0.82V at the 4.5V node so something is loading down the power supply or something else is going on.




I admit I don't have interest in going any further with this SMT stuff. Sure, it's doable with a magnifying glass, small tip, Chipquick, etc but that is not my idea of fun. I also feel somewhat bitter that this lump of excrement has died so soon when I have pedals such as a CE-2 and a DD-2 from the eighties that are still going strong. A turd emoji would be useful here.

I looked at building a Rebote 2.5 in here however the PCB will not fit. Any suggestions on a decent delay that could be squashed in here?

[anotherjim]

I don't know, but maybe a Danelectro Fab Delay pcb can be fitted in the Boss case? That's a small smd PT2399 delay and I think they can be found for cheap.
https://www.diystompboxes.com/smfforum/index.php?topic=113655.0

[Ben N]

I built a Deep Blue Delay clone on a pcb from Aion (on which one can also make a Rebote 2.5), and it is housed in a 1590B enclosure, so I'm pretty sure it would fit in a Boss enclosure as well, although this would require offboard pots and some switching creativity (maybe buffered bypass or a relay-bypass daughterboard). As a basic, no frills short-to-medium delay it is fine.

[Slowpoke101]

Just for your info, quite a few Boss DD-3B delays have failed with the exact same problems as to what you have noted. Most failures where found to be caused by a faulty IC1 (M5218AFP ). When it fails it drags the 4.5V Vref rail down to about 0.8V. Even though it is a surface mount chip you may want to try replacing it with a SMD TL072 OP amp.

[toomanypies]

Thank you for your inputs.

Just for your info, quite a few Boss DD-3B delays have failed with the exact same problems as to what you have noted. Most failures where found to be caused by a faulty IC1 (M5218AFP ). When it fails it drags the 4.5V Vref rail down to about 0.8V. Even though it is a surface mount chip you may want to try replacing it with a SMD TL072 OP amp.

I will give it a go, thanks for that info. The IC is reasonably positioned on the board in terms of access, and may be a less-fiddly introduction to SMT for me. The existing opamp is a JRC14558, with 674H suffix it would appear. I think this is being used as a buffer? Between the TL074 you mentioned, and the 14558 and M5218AFP they probably all pretty much do the same job? I can order whichever. I'm not clear on whether slew rate, noise, etc matter much in this position.

[anotherjim]

I had a quick look at the full schematic. One opamp chip is running at a lower voltage to suit the digital circuitry and is in a 14pin package. The one that fails is running off the 9v DC and that is a standard 8pin dual opamp. Fitting an SMD 4558 will keep it original, but as said above, a TL072 will work too.
That said, I'm unsure why that chip should fail as it's buffered by other parts from the input and output. Possibly the wrong power supply has been used and the voltage regulator saved the low voltage circuits while that opamp took the brunt of it.

[Slowpoke101]

I think that Jim's advice of using a JRC chip would help keep the pedal as original. There is no real difference with reliability issues between using a 4558 or TL072.
Over the past 3 years I have repaired 17 of these Boss delay effects pedals. 12 of them had failed due to IC1 failing. There does not seem to be any reason for these failures. Replace the faulty IC1 with a standard SMD 8 pin dual OP-Amp and it seems to not drop dead ever again. I have not been able to investigate as to why IC1 failed but I have had no returns or complaints. The only advice I gave the clients was not to insert or remove a powered DC cable - turn everything off. Perhaps this helped? No idea.

[toomanypies]

All good information, thank you. However things have not gone well. After desoldering the opamp it was apparent that there was a vacancy where C8 was marked on the board. It is gone. Sure enough I inadvertently hoovered it up with solder wick. I found it in the trash stuck to a piece of solder wick    I have no chance of reinstalling this thing with my current equipment, it's miniscule.

I will go with a Deep Blue Delay... I have most of the bits for that