Author Topic: Rust bucket Voltages way off  (Read 472 times)

Stomptown

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Rust bucket Voltages way off
« on: September 09, 2017, 10:58:05 AM »
So I built the rust bucket a long time ago and based on the notes in the build doc I initially thought it was working as expected. However, after listening to Demos from other members builds I started to think something might be off.  I finally pulled it out the other day and measured voltages and found a bunch of inconsistencies with respect to those included in the build doc.  In particular,  ICs 7 through 10 are off.  Strangely, the voltages on pins 1 and 2 of IC7 are reversed??.  The emitter of Q2 is also way off from the listed voltage.  Voltages are included below. Any help debugging would be greatly appreciated.

Jon

« Last Edit: September 12, 2017, 07:37:16 PM by Stomptown »

selfdestroyer

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Re: Rust bucket Voltages away off
« Reply #1 on: September 09, 2017, 11:56:04 PM »
This is my fear also.. I have yet to populate mine since I just imagine having to troubleshoot 13 ICs. lol

I can't offer you any help but I feel for you bro.

Stomptown

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Re: Rust bucket Voltages away off
« Reply #2 on: September 10, 2017, 12:03:20 AM »
This is my fear also.. I have yet to populate mine since I just imagine having to troubleshoot 13 ICs. lol

I can't offer you any help but I feel for you bro.

As long as you use sockets you should be fine.  In other words, don't be an idiot like me...  ;D
This is my fear also.. I have yet to populate mine since I just imagine having to troubleshoot 13 ICs. lol

I can't offer you any help but I feel for you bro.

Stomptown

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Re: Rust bucket Voltages away off
« Reply #3 on: September 10, 2017, 12:56:24 PM »
Bump

madbean

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Re: Rust bucket Voltages away off
« Reply #4 on: September 10, 2017, 01:03:25 PM »
It's possible I wrote down incorrect voltages (I've certainly been known to do that). I can dig mine out and double check.
I own madbeanpedals (duh). I am part owner of Function F(X).

Stomptown

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Re: Rust bucket Voltages away off
« Reply #5 on: September 11, 2017, 07:55:48 AM »
Thanks Brian!

Govmnt_Lacky

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Re: Rust bucket Voltages away off
« Reply #6 on: September 11, 2017, 01:37:34 PM »
This problem has the distinct smell of a bridged trace somewhere.

The wrong power is getting sent to the wrong pin. Recommend a quick scrape between every IC and transistor pin.

Stomptown

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Re: Rust bucket Voltages away off
« Reply #7 on: September 12, 2017, 07:41:13 PM »
This problem has the distinct smell of a bridged trace somewhere.

The wrong power is getting sent to the wrong pin. Recommend a quick scrape between every IC and transistor pin.

Well I did a scrape between pins but unfortunately the voltages are still off.   :'(

madbean

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Re: Rust bucket Voltages way off
« Reply #8 on: September 16, 2017, 06:19:09 PM »
I'm sorry - I got distracted by other things the last couple of days. I will get mine out tomorrow and look at the voltage chart.
I own madbeanpedals (duh). I am part owner of Function F(X).

Stomptown

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Re: Rust bucket Voltages way off
« Reply #9 on: September 16, 2017, 08:48:14 PM »
I'm sorry - I got distracted by other things the last couple of days. I will get mine out tomorrow and look at the voltage chart.
No worries; I appreciate the help.  I'm not sure if this is useful but I highlighted the areas where it appears I'm having issues (with the exception of Q2 which is also off):



« Last Edit: September 16, 2017, 08:59:32 PM by Stomptown »

Stomptown

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Re: Rust bucket Voltages way off
« Reply #10 on: September 16, 2017, 08:48:44 PM »
I'm sorry - I got distracted by other things the last couple of days. I will get mine out tomorrow and look at the voltage chart.
No worries; I appreciate the help.  I'm not sure if this is useful but I highlighted the areas where it appears I'm having issues (with the exception of Q2 which is also off):



« Last Edit: September 16, 2017, 08:59:52 PM by Stomptown »

Govmnt_Lacky

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Re: Rust bucket Voltages way off
« Reply #11 on: September 17, 2017, 04:12:17 PM »
Look like, most likely... it's IC8 that is causing your issues.

madbean

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Re: Rust bucket Voltages way off
« Reply #12 on: September 20, 2017, 05:07:46 PM »
I spot checked some voltages on my build and what I have on the chart seems to be pretty much correct (I did not check all possible pins).

Like GovtL said, IC8 is one of your problem areas but IC9 is also causing an issue. You've got 5.6v across the board where you should be having a lot of 0v (or near 0). But then, you have several other problem IC's as well. Whether or not those all trace back to one root cause is very hard to say (with so many ICs).

Here is what I do in these situations (and believe me, it will suck). You need to start testing these chips individually. I would start by pulling IC7, 8, 9 and 10 then do comparisons with the remaining chips and the reference voltage chart. If things start to check out then start popping those pulled ICs back in one at a time while comparing voltages to the chart again.

There is no easy or fast way to solve a problem like this...you just have to get in there and isolate the chips that are screwing up the build and replace them or look for something that might be causing good chips to go bad. I remember that I actually had a similar problem when I was putting this project together - actually completely unprecedented in all my building: I had three bad ICs in one build. It wasn't the design or my build but three different ICs that were bad (I think one CA3080, an LM311 and one other one).

Also, please upload a pic of the top of the board - I'll look it over for anything that jumps out.



I own madbeanpedals (duh). I am part owner of Function F(X).