Roland Jet Phaser Problems...

Ammscray · September 13, 2003, 03:51:43 PM

I have a jet phaser that I've had for years, always worked perfectly...after not playing through it in a few months, I plugged it in and there was sound in the effected setting but no distortion and no phasing...

So I changed one 2902 and got the distortion back...changed another and got the phasing back...for about 5 days...now it's back to where it was with no phasing and just the distortion...I threw the original ICs out assuming they were bad but I guess maybe not...I thought it was very strange that two would fail at the same time just like that...

Anyone have any experience troubleshooting these, or have a hunch what would cause the ICs to fail?

Thanks in advance!

Rodgre · September 13, 2003, 04:02:57 PM

I have one that hadn't been used in many years, and it didn't work.

I cleaned the pots and rotary switch and voila. She's perfect now!

Roger

petemoore · September 13, 2003, 05:30:41 PM

say...actives like IC's if they get to leaking heavily...[ ?]

Ammscray · September 13, 2003, 05:41:39 PM

The strange this is, is that when I accidentally touched one side of a diode on the board to ground, the phase flip-flopped over to the other side of the sweep...and I could actually get it to work but repeatedly touching that point to ground and quickly lifting it... :?

so the phase is in fact stuck...I replaced the diode but it didn't make any difference...

Rob Strand · September 13, 2003, 07:26:59 PM

I think someone had a problem with one of these not too long back and it turned out to be a bad IC (which you can check by measuring the DC levels at the output of each opamp). The other possibility is the cap just before the JFET gates has gone leaky.

zachary vex · September 14, 2003, 04:45:47 AM

if they were in sockets, the most likely thing is that the socket contacts oxidized and were cleaned by scraping as you removed the old chips and put in new ones.

Ammscray · September 15, 2003, 06:57:22 PM

Hi I'd just like to thank all you gentlemen for your suggestions with the jet-phaser...

it turned out to be an intermittent trimpot...several swapped out IC's and FET's later...

never had that happen before...

At leat it's working, this one would be hard to live without...
Peace!

Bill Bergman · September 15, 2003, 11:28:44 PM

That's why I built one. Now it's the coolest phaser I have also.

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Roland Jet Phaser Problems...