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Drawdio! on mute
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Please be positive and constructive with your questions and comments.

Drawdio! on mute

by wen on Tue Jun 01, 2010 6:12 pm

At the advice of adafruit personnel, I am posting my 8th-grade son's non-functioning Drawdio! project for review.

The device was assembled at school under some adult supervision. A solder practice kit allowed him to acquire the requisite soldering skills. According to him, a clip-on heat sink was employed whenever possible. The instructor tried debugging it by testing the speaker and battery. After the last class, he brought it home still silent. I verified the resistors with a multimeter. Further testing will require either disassembly, more sophisticated test equipment or both. Attached are photos of the front and back side of the device. TIA.

Any thoughts?
Attachments
IMG_7368a.jpg
drawdio back
IMG_7368a.jpg (679.16 KiB) Viewed 1813 times
IMG_7367a.jpg
drawdio front
IMG_7367a.jpg (605.56 KiB) Viewed 1813 times
Last edited by wen on Wed Jun 02, 2010 2:12 pm, edited 1 time in total.
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Re: Drawdio! on mute

by adafruit on Tue Jun 01, 2010 6:21 pm

looks pretty good - are there any solder joints that look like they may be 'cold' ? they should all be very solid - the shininess makes it tough sometimes to tell. some look a little marginal
check the printing on the transistor, it should say PN2907, in case it is wrong
another thing is we cant see the speaker, was that soldered correctly?
when testing was the battery inserted the right way?
then of course you have to touch the tabs with your fingers to get it to squeek

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Re: Drawdio! on mute

by wen on Wed Jun 02, 2010 1:05 am

Thanks for the reply.

Every joint is solid and meniscus shaped (at least on one side).
The transistor is labelled pn2907k45.
The speaker is soldered properly and was found to be operating by the instructor. A picture is attached.
The battery is attached correctly as designated by the PCB and the voltage is nearly 1.5v.
No squeak is detected using fingers or other conductive materials
Attachments
IMG_7410a.jpg
speaker leads
IMG_7410a.jpg (514.95 KiB) Viewed 1805 times
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Re: Drawdio! on mute

by wakeupsilver on Wed Jun 02, 2010 9:18 am

If this were my circuit, I would do the following things in this order:

1) hit all the solder joints with a soldering iron and make sure the connections seem for sure (for example C1 looks a little funky possibly)
2) replace the transistors with new transistors (only slightly annoying to do)
3) replace the 551 timer chip (pretty annoying, but the most likely problem)

If it still didn't work I would be confused and need to regroup.
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Re: Drawdio! on mute

by adafruit on Wed Jun 02, 2010 11:15 am

wakeupsilver wrote:If this were my circuit, I would do the following things in this order:
1) hit all the solder joints with a soldering iron and make sure the connections seem for sure (for example C1 looks a little funky possibly)
2) replace the transistors with new transistors (only slightly annoying to do)
3) replace the 551 timer chip (pretty annoying, but the most likely problem)
If it still didn't work I would be confused and need to regroup.


hey wen (adafruit support here) - jay is the creator of the drawdio, you're welcome to try these suggestions or we can send out a postage paid envelope with a new kit, we'd ask that you send back the kit you assembled and we'd likely be able to see what's wrong in a matter of seconds. let us know (email support@adafruit.com if you'd like to do this).

thanks for popping in jay! great suggestions!

cheers,
adafruit

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Re: Drawdio! on mute

by wen on Wed Jun 02, 2010 12:39 pm

To WakeupSilver:
The tinkering side of me thanks you for your thoughtfulness.
1) I will have my son hit the joints again. As I stated before, the joints in question are solid on at least one side of the PCB.

I agree with your assessment that either the timer or xsistor has failed.
2) Although these parts are inexpensive (maybe $5 total) the S&H costs are outrageous especially at n=1 and is potentially more than a new Drawdio kit!
3) In my experience from a long time ago, manually pulling a soldered, non-socketed, multilegged component from a PCB typically requires the sacrifice of one or the other. To salvage the PCB, I would consider cutting the timer leads and desoldering them separately.

To adafruit support:
The practical side of me thanks you for saving me from my tinkering self. I will send you email directly to setup cross shipment.
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Please be positive and constructive with your questions and comments.