Tube Fex

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tanusgreystar
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Joined: Fri Jun 17, 2011 11:41 am

Tube Fex

Post by tanusgreystar » Sat Mar 12, 2016 12:42 pm

Starting a new thread because noone seems to be answering my other one. Right now, the only thing thats wrong with the Tube Fex is there is no output. You can hear it turn on through headphones, but no sound. The sliding pot doesn't seem to move on its own. but the clip light goes on. Would a new sliding pot fix this issue? Thanks.

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MidiMan
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Re: Tube Fex

Post by MidiMan » Tue Apr 05, 2016 10:24 am

The internal motorpot is only for the TB "effect" block (the tube preamp). You can go to just about any preset and replace TB with DS (digital distortion) and see if that makes the unit work (as a test). If taking TB out of the preset makes the unit work, then the motorpot might be the only issue. If it does NOT make it work, then there's something else going on, because the motorpot is not even in play at that point.
John Fera
Peavey Digital Engineering

tanusgreystar
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Re: Tube Fex

Post by tanusgreystar » Sun Apr 10, 2016 7:31 am

No sound with DS either.

tanusgreystar
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Joined: Fri Jun 17, 2011 11:41 am

Re: Tube Fex

Post by tanusgreystar » Thu Apr 14, 2016 8:03 pm

Any thoughts? I have another unit for parts so if there is a chip or other part that controls the output, I may have it.

Swellsound
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Location: Virginia

Re: Tube Fex

Post by Swellsound » Wed Mar 20, 2019 4:43 pm

Based on the info you've provided it's hard to do much more than throw out wild guesses, as there are quite a few places where the signal could be getting killed. I don't know how proficient you are with electronics, but the schematic is 16 or 20 pages, and there's lots of circuitry.

Do you have an oscilloscope? It's really not practical to work on a unit as complex as the Tube Fex without a scope, but a voltmeter would be a good place to start even if you don't have a scope.
1. You want to check all of the voltage rails first. There are plus and minus 15 and + 5 regulators in TO-220 packages near the transformer, and a -5 (to-92) near the motor pot.
2. If all the voltage rails are okay you might want to check the J111 fets, next. They tend to be sensitive and prone to failure.
3. The relays are probably the next place I would check. You can't get to the pins on the relay without removing the PCB, but you can check capacitors and resistors and other components feeding the contacts of the relay, using the schematic to help guide you trace the signal flow.

Oh, and if yours has not been upgraded to use non-volatile RAM, you should make sure that the battery has been replaced. If it hasn't, it's only a matter of time before it leaks out and starts eating away at the traces, and getting under the TL072 and 74hc32, and associated components, near the battery. When that happens it can do some serious damage that may result in corroded or lifted pads when you try to remove and replace the components that suffered from all the electrolytes from the nasty battery juice.

BTW, does anybody have the .bin file for V2.0? Mine has version 1.5 firmware, and I haven't been able to find the code online, or even anyone who is selling V2 eproms. Any help would be greatly appreciated!

Thanks,
Sam

Swellsound
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Location: Virginia

Re: Tube Fex

Post by Swellsound » Wed Mar 20, 2019 4:56 pm

Hi John, I just recognized your name from some old posts on a different forum, and someone mentioned that you are the design engineer behind the V2.0 upgrade, if I understand correctly! Anyway, I've been trying to locate the firmware or a source for the eprom to no avail.

I just got finished repairing a Tube Fex that had suffered the infamous leaky varta battery syndrome, and after replacing the battery, and the 74hc32 and TL072 (U600 and U511?) and a few other associated components, it came alive! Oh, and fets Q900 and Q902. It's an awesome processor, and I would love to upgrade it to V2.0 if possible. Any assistance or guidance would be greatly appreciated!

Thanks,
Sam


MidiMan wrote:
Tue Apr 05, 2016 10:24 am
The internal motorpot is only for the TB "effect" block (the tube preamp). You can go to just about any preset and replace TB with DS (digital distortion) and see if that makes the unit work (as a test). If taking TB out of the preset makes the unit work, then the motorpot might be the only issue. If it does NOT make it work, then there's something else going on, because the motorpot is not even in play at that point.

tschneids
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Joined: Sun Apr 04, 2021 7:01 pm

Re: Tube Fex

Post by tschneids » Sun Apr 04, 2021 7:11 pm

Tube Fex - No Output - working for now!

I had the dreaded battery leak issue that looks to have corroded some part of the PCB, and ruined a couple of traces. I'd like to eventually fix the battery issue, but for now I'll take it. I was able to solve this by seemingly bypassing the mute circuit which looks to have been ruined by the corrosion with a manual override toggle. There seems to be not very many owners of these things anymore, but I would be happy to share what I did. I love the sound of this unit and it hasn't been replicated with today's software. Hasn't been posts in a while.

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