Orange Micro Terror

Tube or solid-state, this section goes to eleven!
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Ichabod_Crane
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Post by Ichabod_Crane »

Yes, I didn't analyze the schematic with much careful. I need to look that well.
Indeed, it was strange even if I didn't thought about it. :)

Tha guy who drawn the schematic said that is tracked from the original amp, but of course he admits some mistake can be there.
It's suspect the Tone section. Some mistake is possible, but I guess we can't "read" the Big Muff tone style instead a Vox Style by mistake.
And the Volume pot value? 100k or 25k is just supposed?
Even the two last stages, those drive the Aux In jack and the Phones jack, but it's possible that two stage need to the signal tracking.

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mojorootietootie
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Post by mojorootietootie »

This is an old thread but I have to set the record straight. Valiant effort by camljenkins94 but the original schematic posted in https://gitlab.com/jofirel/uterror-amp/ ... master.zip is >90% correct. The board has 2 layers and many of the traces are covered by the components making it impossible to trace from the photos alone.
I was able to trace the board from micro terror SN 10131-1112 by using a combination of visual and multimeter probing so I am quite certain of the results.
Kudos to José Relvão who did the original tracing. The following are where his and my tracings differ:
1. R2 wired to Vbias and not GndRef
2. Gain circuit C7 connected to VR1A wiper not to R8-C6 node.
3. R17 is 220k instead of 100k
4. R20 is 47k instead of 150k
5. R22 is 220k instead of 1M
6. Several discrepancies in power section. Most notably, Tube heater powered via 12V regulator. See attached schematics for more details
7. STA540 pin 6 connected to C32 47u cap. This is missing in the original.

Of special note is the tone control circuit which is 100% correct including the dubious short across R24. I suspect this was added by the original designer as a means of detecting if the design was copied since it makes no sense. Of course, it could always be an oversight by Orange :) . I would just leave out R24.
I have modified the original schematic and attached it below.
Attachments
uTerror R2.pdf
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mojorootietootie
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Post by mojorootietootie »

Oops. Forgot to update speaker out jack JK3. :oops:
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Post by orcl2 »

:applause: thx Man, i'll test It skin.

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J0K3RX
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Post by J0K3RX »

@mojorootietootie

Take a look at R24/R25. It appears R24 is shorted as member deltafred pointed out in the Orange Terror Stamp post.

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mojorootietootie
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Post by mojorootietootie »

See my original post wrt short across R24.

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