Question about Ibanez SDR1000+ intermittent noise in 1 output channel

[BramP]

Hi everyone, so I recently discovered the beauty of old digital rack reverbs and got my hands on an Ibanez SDR1000+, it sounds lovely, however after operating for a while (can be anywhere from 10 minutes to half an hour) one of the outputs gives me a hiss and some faint rumble, the unit still functions and produces sound in this channel though.

Now I'm not a great technician but my first guess would be an electrolytic cap reaching the end of it's life (I believe the unit is from 1986 or there about) somewhere in the analog output section, would it be best to simply do a recap of the entire unit or pinpoint the exact culprit?

I'll add some pictures.

Greetings, Bram

 

[BramP]

Second picture is what I believe to be the analog output section

 

[Ike Zimbel]

If it takes time to occur, it's most likely heat related. Personally, I would check everything else first, before re-capping. Re-seat connectors and socketed IC's (if any, couldn't tell from the pics), tighten mechanical connections, check to see if any devices mounted on heat sinks get hotter than their neighbours. It could very possibly be an issue with one of the low-pass filters...the rectangular metal cans you see near the middle of the boards. You could give those a feel to see if they get overly warm. These are a known point of failure in other digital devices from that era...Lexicon 480-L etc., Eventide H-3000...

 

[BramP]

If it takes time to occur, it's most likely heat related. Personally, I would check everything else first, before re-capping. Re-seat connectors and socketed IC's (if any, couldn't tell from the pics), tighten mechanical connections, check to see if any devices mounted on heat sinks get hotter than their neighbours. It could very possibly be an issue with one of the low-pass filters...the rectangular metal cans you see near the middle of the boards. You could give those a feel to see if they get overly warm. These are a known point of failure in other digital devices from that era...Lexicon 480-L etc., Eventide H-3000...

I took the top off so I can run it and check the heat, the low-pass filters on the channel that gave me problems also make a noise when touched as if they're losing contact for a moment. The noise issue I had earlier is not occuring anymore, it's been running for more than an hour.

So I think good call and I'll resolder these filters?

 

[BramP]

The noise came back but seems to disappear when switching the input/output from minus 20 to plus 4.... if it stays quiet this way ok by me

 

[CJ]

Give it the deoxit treatment, inspect for bad solder joints, especially around the pots and go from there.

 

[BramP]

Check, I cleaned the board up with some de-oxit and resoldered some dry looking connections, particularly the ground buses. Unfortunately the issue continues, but last night I aimed a big fan on the exposed board while running it and it ran flawless for 2,5 hours. So that clears any doubts whether it is a heat related issue I would think. Now when not fanned the heat sink above the words 'power supply' gets especially hot compared to the others, my guess would then be that probably one of the components nearby is losing it from the heat.

 

[58Glammer]

Hi, I would recap the powersupply section. I recapped a Amek 400 powersupply a while ago and now it‘s not that hot anymore and has the power again to supply the console very nicely.
Also I have a Ibanez DD100, a two channel digital delay, that was completely dead.. the recapping brought it back to life.
Recapping a 86 unit makes totally sense.

 

[Bo Deadly]

Use a can of "air duster" to gently blow cold air onto specific parts. Use the nozzle tube to get the air right up against a particular part. Try parts that are power related like regulator ICs, rectifiers and transistors. If the noise goes away or gets noticeably quieter when cooling a particular part, that would be the part to replace.

When power related silicon parts start to fail, they get burned up inside and become slow to turn on / off or don't turn on / off completely.

Alternatively a scope would go a long way. You would probably see the supply becoming noisy or be able to trace the source of the noise.

 

[hageir]

Howdy,
I have four of these I bought on a whim (all of them mostly not working).
Fixed one immediately by trying fixing the most common failure; you see those copper buss bars (some of them carry GND and one +5V IIRC).
The single sided paper boards used on these have a tendency to have cracked solder joints (the boards are too flexible).
Heat up those buss bar joints and see if it cures your problems..

The rest of mine all had the same fault, there's this really weird circular (loop) bias controlled power transistor set up, so if one transistor fails in that loop, it takes the other two with it..
Had to find and order NOS 2SD809K (pretty rare) but the others are replaceable (1152 and KA30 or something IIRC).

but those were power related problems, no effected signal and so on..

But totally worth fixing!
True stereo btw (two separate mono channels; two full reverb processors in total).

Sure, it does really classic sounding 80s reverbs (quite metallic sometimes) and that on its own is very nice to have..

But as soon as you "shrink" everything down (especially the time) it became a VERY natural sounding reverb, almost unbelievably good!