Mystery component ID - HBE T.H.C. Chorus

[Strategy]

Hi all,
I have come into possession of a dead Homebrew Electronics / HBE T.H.C. Chorus.
I haven't spent much time analyzing it yet but noticed a part that I'd never seen before, or more likely it's something unsurprising but in a format I happen to have not seen before.
It's the thing that looks like a grey resistor with two silver stripes and a grey body. And, appears to be damaged. I wondered if it might be a ferrite bead sort of thing since it's near the power input.



Thanks for your help!
Strategy

[antonis]

Why not a discoloured 4k7 resistor..??
(like the left one, right down the green cap)

[Strategy]

Maybe! I hadn't noticed the grey resistor there among the blue ones.

[Rob Strand]

Why not a discoloured 4k7 resistor..??
(like the left one, right down the green cap)

It's definitely the same type of resistor as that one.

Resistors that look like that are often flame-proof types.  They have a matt, pitted surface like a ceramic.
You can also get normal resistors with a similar color but they have more of shine, although not entirely gloss.
It can be a fine line if you aren't familiar with both types.

It does look damaged.  I have doubts a 9V or 18V circuit would fry a 4k7 so it's likely to be 1R, 10R, 100R.
It could also be a 0R.  A shorted tantalum cap on the power rail could cause a low value resistor in series with the power to fry.

You would need to trace the circuit in that area, or, find a pic of another unit.

Well clearly that design has an issue frying that part.  Try measuring the value!

[Strategy]

so for some reason I cannot access this website ("IP address banned" - weird since I can't recall ever visiting / using this site) but it appears to contain the only gut shot currently online anywhere:
https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSWWdBuCRW6CDi7Ad-3BiJ9F7lHLp2H3TQTEA&usqp=CAU
On google images it looks a little rezzy but to me it looks like a 1Nxxx diode in this same position.
Sadly there are not schematics anywhere that I can find for this.
I'll try everything you suggest Rob Strand. I would be unsurprised to find failed tantalum capacitors in this unit.
Strategy

[Rob Strand]

Try this, zoomed section,

[Click to Enlarge]

[Strategy]

Thanks Rob! I'll measure the part resistance when I get home. I have a hunch I'll discover it's a 0 ohm resistor.
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[Rob Strand]

See how you go.  With any luck it might measure OK.

I found this on another HBE pedal.  One good board and one bad.  The good board looks like 1R.

https://en.audiofanzine.com/other-guitar-saturation-effect/homebrew-electronics/Big-D/

On one hand designers use similar circuits for power, and on the other hand there's a risk
of extrapolating too much info from a different pedal.

If you look through some of the threads on the FSB forum, a few pedals there have 10 ohm
resistors in series with the power rail.  Some were lower drain.  Unfortunately I couldn't
see the Flanger pics (and no Chorus).

[Strategy]

Well. That mystery resistor measured 10k. It crumbled to bits when I started debugging probing around in the circuit to see what's going on.
Replacing the tantalums and that resistor didn't help, and I'll have to trace through HBE's wiring as I discovered a broken lead there and not sure what it connects.

[Mark Hammer]

IIRC, HBE was started by a former member/regular here.  Assuming they're still operating, one would think/hope they'd be open to a query from a current member.

[ElectricDruid]

Glooping half the components with stuff so you can't read the part numbers doesn't speak highly of their openness.

What's the point of that when we're looking at a circuit that's most likely a CE-2 spin-off anyway?

[Govmnt_Lacky]

What's the point of that when we're looking at a circuit that's most likely a CE-2 spin-off anyway?

My money is on Small Clone. Thinking that larger IC is a 4047 

[Kevin Mitchell]

What's the point of that when we're looking at a circuit that's most likely a CE-2 spin-off anyway?

My money is on Small Clone. Thinking that larger IC is a 4047 

Spot on!

This is the layout provided from Tonepad
Burnt resistor is 47 ohms.

People masking parts on an open source project are clowns.

[Govmnt_Lacky]

People masking parts on an open source project are clowns.

Well.. in fairness, they did modify the layout by moving Q3 

[Kevin Mitchell]

People masking parts on an open source project are clowns.

Well.. in fairness, they did modify the layout by moving Q3 

Such an engineering feat!
I'd say they also use poly box film 1uFs instead of electros but with all that epoxy covering them, I guess we'll never know the secret sauce 

[Rob Strand]

Well. That mystery resistor measured 10k. It crumbled to bits when I started debugging probing around in the circuit to see what's going on.
Replacing the tantalums and that resistor didn't help, and I'll have to trace through HBE's wiring as I discovered a broken lead there and not sure what it connects.

Well, looks like it is actually burnt.  There's a good chance anything from 1R to 100R would work.

I like Govmnt_Lacky's suggestion it could be a Small Clone ... clone.  That would help with a sensible value and the broken wire.

Trace some of the circuit out against the Small Clone schematic.

[Mark Hammer]

IIRC, HBE was started by a former member/regular here.  Assuming they're still operating, one would think/hope they'd be open to a query from a current member.

Nope, I was wrong.  Different person entirely.  Never mind.

If the THC was a derivative of the Zombie Chorus, one would also see the same chip complement, except the bigger chip would be a CD4046 phase-locked loop chip.

[ElectricDruid]

If the THC was a derivative of the Zombie Chorus, one would also see the same chip complement, except the bigger chip would be a CD4046 phase-locked loop chip.

Ok, so there's potentially three possibilities, but even so, we know exactly what's in each of them and it'd be straightforward to determine what it is we're looking at, so there's really no point glooping it. Sigh.

I wish they'd spent that amount of effort making sure it didn't catch fire instead.

[Rob Strand]

This thread confirms the IC's are the same as the Small-Clone,
https://www.thegearpage.net/board/index.php?threads/hbe-thc-chorus-which-chip-is-used.1438545/page-2

From what I can see from this pic, the (previously burnt) resistor is Brown Black Black Silver = 1 ohm.
There is a 47 ohm (Yellow Violet Black Gold) next to it, which might be the 47 ohm on the Small-Clone.

[Strategy]

Thanks everyone for piling on this and re-posting the Gear Page link which, when I try to look at it from my office, is blocked, but here I can see it while logging on from home. The site must not like my (totally not music related) company's IP address for some reason.

I can confirm the logic chip in this HBE is a 4047. I'll swap out the 10k I put in for a 1R or similar low ohm item there.
I replaced the tantalums with electrolytics but perhaps I should not have done?
I do need to trace all the way through starting with 9V and ground as the thing just won't even power up and I don't feel completely certain all the jacks and wiring are all good still.
All that being said build quality and construction generally are good

The gooping is ridiculous.
Thanks to all greatly appreciated!!
Strategy