H3000 D/SE digital Noise on 1 Channel

[mrknits]

Hi I just noticed this issue on my rackmount H3000 D/SE. 

There is a low but noticeable digital noise whenever I have a signal coming in on the left channel. It is most noticeable at the end of the signal it sounds like a noise gate opens up for a fraction of a second, but upon further inspection the noise goes over teh whole channel. At times the noise goes away. If I only put a signal in on the right channel, there is no noise. The noise makes itself evident on the left output. I can provide a sound sample if that would help. Anyway have any idea what would cause this? Its not a hum, but a high frequency digital noise/distortion.

I’ve isolated the issue and made sure it is actually coming from the Eventide unit and not any cabling or the audio interface.

[nickrose]

Unfortunately the 3000 series is now almost 40 years old and we have no-one here who understands them, nor can we get many of the parts, so we can no longer support or repair them.

If you think you have a hardware fault, you could contact David Kulka at http://studioelectronics.biz who can repair gear of this vintage.

 

 

 

[Spindrift]

Hello, I have the same issue on an H3500 DFX-Sampling unit, except it happens on the right channel. I have soldered the leads to the pins and ditched the troublesome molex connector and also have recapped the PSU filter section (6 large caps on underside of board).  The noise remains.  Has anyone come up with the source of this digital noise?

 

Thanks.

[noodle1]

What do you mean “digital” noise?
Also on the 3000, the filtering, feedback, and gain around the A/D/A are analog, unlike newer devices

I wouldn’t trust many techs poking around in a 3000, you want a guy who can do the job right and who knows the schematic/operation well who can get in and get out with the lightest footprint. But if this sounds like too much trouble/money, I’d probably take it off your hands for you…

[noodle1]

From StudioElectronics:
“Note: in recent years many H3000’s have come to us with dead power supplies, sometimes with customer comments about smoke from the motherboard and burning smells. These problems are nearly always caused by shorted capacitors, which can cause additional failures in the power supply circuits. In these cases repair and testing can be very time consuming because the motherboards have dozens of capacitors in parallel, there’s no easy way of individually testing them, and often many (or most) need to be replaced.”

Full service check up runs around $800-1000, good for people who want to keep this beast in their studio!

[noodle1]

Also, try Beamish Electronics in Ohio

[Spindrift]

Thanks, I hope to getting around to printing a clip of the noise (that I can upload) during next mix session. The way the OP described the noise above is spot on. I have already recapped the PSU.

[Spindrift]

Well, I managed to solve my bit noise issue in the right channel of my H3500. I carefully unseated each socketed IC and brushed off the pins with some Gold DeOxit and carefully reseated, making sure that no pins were bent underneath the chip upon insertion.  I did find one IC in the attached photo (yellow circle) that had a pin bent underneath it that wasn’t making contact. I don’t know the function of this IC but it could have been the culprit in the bit noise I was experiencing….or not. It could have also been the IC pin cleaning job. Not sure, but either way, I have clean IC pins and a 100% noise and trouble free H3500 now!

Caution, if you don’t know how to pull and reseat delicate ICs properly, watch a decent YouTube video on it first before undertaking the endeavor because you can damage some pretty hard to find chips if you don’t know what you’re doing.  A cheap IC extraction tool or two from Amazon will save you lots of headaches.

Attachments:

You must be logged in to view attached files.

[noodle1]

Thanks for the followup, I was wondering how things were going on this…
Thats the right D/A converter…
Socketing of I/Cs is both a blessing and a curse!

For those who have problems, always check ribbon cables + the ROMs and other socketed ICs…
The 3000s are hardy devices!

[Author]

Posts