Fried my HOF mini

fastonebaz

I think i fried my HOF mini by running it on an incorrect power adapter of 6v instead of 9v ( and probably incorrect current) because now when running on a proper 9v power source the pedal is engaged the led lights up but volume drops to about 5% volume, disengaging it returns to normal bypassed audio volume levels.  

So... what are my chances of being able to fix this myself if i open her up?  Am handy with a solder but not an electrical engineer. 

ICBM

Zero.

Sorry.

I won’t even look at these any more. It’s just a waste of time - they’re never economically repairable even if it’s something apparently simple.

This isn’t a trivial fault - if the LED comes on it’s not a protection diode or voltage regulator that’s gone, it’s one or more of the signal ICs.

fastonebaz

Damn it.  Thought as much.  That'll teach me to use a dodgy power supply.   

Philtre

Can you access it via the mini USB port and the software?

fastonebaz

I haven't tried that yet.  What were you thinking i could do if that worked?

Philtre

See if the tone print software can access the unit. If it can, then maybe that's a good sign. Maybe can reset the firmware...

fastonebaz

Aha yes maybe it's a software glitch

clarkefan

Why would 6v instead of 9v damage a pedal?

ICBM

clarkefan said:

Why would 6v instead of 9v damage a pedal?

It wouldn't normally. My guess is that the polarity was reversed as well.

Hopefully it is a software glitch, but I would be very surprised. If it is, this is very useful to know!

fastonebaz

It was negative centre

fastonebaz

Will report back on software on due course. 

Philtre

Should be OK then if only 6V. DId you check via USB yet?

fastonebaz

Not had a chance to check usb yet however the adapter i used was 6v but 600mA! Yikes

Philtre

600mA is the maximum current draw. The pedal won't draw that much, it will only draw what it needs.

ICBM

If it was the right polarity that increased the chances of it being a software fault that was somehow triggered, I think.

Or it could be an odd coincidence and the pedal just chose this moment to die spontaneously... which wouldn’t be unknown for a TC.

fastonebaz

@Philtre ; @ICBM ; GUYS YOU ARE AWESOME!

I followed the steps to update the firmware on the HOF mini and it's all working again perfectly.  Thanks for the great suggestion, it worked a treat.  I'm reverbing again.  Thanks!

Philtre

Excellent. I love it when a plan comes together. ;-)

ICBM

fastonebaz said:

@Philtre ; @ICBM ; GUYS YOU ARE AWESOME!

I followed the steps to update the firmware on the HOF mini and it's all working again perfectly.  Thanks for the great suggestion, it worked a treat.  I'm reverbing again.  Thanks!

Fantastic! I will now recommend this as a first thing to try to any customers with dead TC pedals - it's at worst a shot to nothing, given that they're probably not going to be repairable anyway if there's any actual electronic damage.

It's nice to be wrong sometimes .

I am now starting to wonder if the apparently high 'lights on but no-one home' rate with TC pedals could be largely down to this - after all, if a too-low-voltage power supply could mess up the firmware enough to effectively kill the pedal, what's to stop that same thing happening if you switch off the power supply at the wall without unplugging the pedal first - since the voltage will drop as the caps discharge and at some point will pass through 6V...

thermionic

Don’t tell everybody... I’m off to ebay to look for some cheap “for spares/repair” TC pedals.

Philtre

Talking of wiring up a pedal with reversed polarity, haven't all pedals got at least some kind of rectifier protection in their circuit?

ICBM

Philtre said:

Talking of wiring up a pedal with reversed polarity, haven't all pedals got at least some kind of rectifier protection in their circuit?

Most - yes. All - no.

Even the most that do are usually done with just a reverse polarity diode across the input. This is very crude and - especially nowadays - not totally effective. In the past, the diode would quite often burn out and short, leaving the pedal unusable even with the right supply or causing a battery to overheat (and sometimes swell or leak).

Now, it’s even worse - modern high-capacity supplies like the One Spot have such a high current capability that they will keep on going even with the diode shorted, and eventually the diode will burn away entirely, then leaving the components it was supposed to be protecting exposed to the reverse voltage and usually killing most of them... making the pedal beyond economic repair.