CORON HM520 Heavy Metal

[Blackboarcult]

I found this one on the Spanish Cash Converters website for 30€ and was more than curious, having found no info whatsoever about it besides a couple of adverts on Reverb selling these for 60-100 €.
So I bought it expecting to find a shitty pedal worth nothing except for collectors. "If I don't like it, I resell it and make some profit, alrighty"
Well I just got it with the mail, and surprise, doesn't work. Scratchy pots, bad connections, barely lighting led. I have opened it to clean and resolder some connections, but while I'm at it... Here's some gutshots.

If someone's interested, I can try to trace it

Coron pedals were apparently famous for being japanese lo-grade clones of MXR and the likes.
If anyone is familiar with this topology and can point me the right direction to compare schematics, I'd appreciate it!
Looks a little bit simpler than the BOSS HM-2 at first sight.
I've ran a search on the FSB forum for the IC's used here (TC4007UBP, C4072HA), but little to no results.
Anyway I'll clean it and test it and let you know how it sounds like.

Oh, and I'm loving the plastic thingie to hold straight the led lugs

Cheers!

   

[GrooveChampion]

TC4007UBP, could it be a CD4007 CMOS chip?

[Blackboarcult]

you're probably right! I quickly compared datasheets, seems to match. Thanks!

Update 1:
I cleaned up pots, all safe and sound and working well.
Well, "well" is not the word... this little fucker sounds utterly disgusting through practically every Amplitube preset  (I'll test it with real amps asap, no time to go to reh room this week).
The only nice sound I got from it was with every knob on 10 and fed directly as a preamp to an EL84 Marshall poweramp emulation. paired with reverb and chorus, it sounds neat to do slow one-string melodies and power chords on 4th and 5th strings.
Other than that, the massive amount of buzzing distortion reminds me of the HM2 and MetalZone, except palm mutes sound dull and woody instead of chugging.
A friend of mine just told me he remembers DOD pedals from the 80's having that same kind of feel when palm-muting when I described the sound to him.

I'm still puzzled about what pedal is copied here... I recall no 4-knobby DOD prior to 1985...

[Travis]

The 4007 is probably used for bypass switching like DOD

I think it probably is based on the HM-2 with the multiple SIP op amps and ge looking diodes

The HM-2 sounds best with all knobs cranked for sure. Make sure not to run too hot signals into your converter for Amplitube etc because the digital clipping tends to sound bad

[Blackboarcult]

Haha no worries, proper analog to digital signal transition is always one of my main concerns

Well it may be based on the HM2, but the low-end response must have been heavily modified. It exhibits an almost sub-sonic rumbling, unlike the HM2's chugging, crushing low-end.

I'll try it with real amps and stuff anytime soon, but I don't really think this one's a keeper, so if anybody wants me to trace it, please tell me before I get rid of it