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Old 16th December 2012, 03:27 PM   #1041
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Quote:
Originally Posted by westers151 View Post

Linux Guru - Do you have any of your boards for sale?
Yup, however they are larger than the TPA v1.2 boards you have. I'd second Uriah's suggestion to try to repair the board - if the pad that delaminated has no trace connected to it on that side, there is no problem and electrical connectivity is the same as before. You can carefully solder the lead to the through-hole.

Alternatively, ask Uriah for a bare TPA v1.2 board if available.

You can check resistances in-circuit without desoldering - just compare with the working board to see if it looks similar.

Finally, check R11 to see if it is close to 1 ohm. This often fails open due to various human errors.
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Old 16th December 2012, 04:20 PM   #1042
bcmbob is offline bcmbob  United States
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If Uriah doesn't have any more, I have a single TP red V1.2 board that is used but appears to be intact. Take a look to see if it is in better shape than yours. You can have it if you want it.
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Old 16th December 2012, 04:45 PM   #1043
udailey is offline udailey  United States
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I only have two left and would like to keep them to build in the future. I have no modules built up or operating so these are truly my last boards from the buy.
With the bad one running you might place your hand flat a half inch or so above the tallest component so you can feel heat rising from the board. It will work. You can even feel the heat from an LED doing this. What I am thinking is you may have a short somewhere and this will usually make at least one part get way to hot. Then you can go to touching cases, but not metal parts to see if something is to darn hot. If your relay doesnt want to click then it has voltage cuz its closing a tiny bit but not all the way.
Look for solder flags on the bottom of the board. Soldermask is not as good as it should be with some board manufacturers. Sometimes you can put a microscopic scratch on the mask just by shipping two boards together. Then you solder and a little flag comes off of the through hole to that scratch and you have a short to the ground plane or another close trace. You will lose voltage here as there will now be a loss of current and it basically makes a voltage divider. I know you have probably reflowed the solder joints but its something I run into from time to time with boards built in China because the mask is not very good. My easy fix is to flux each joint and then heat it. Works every time. Rosin flux solder is not as good as real flux plus rosin core solder. If you dont clean your tip and remove excess solder then rosin core solder will get thick and sludgy and these flags are easy to make. Real flux often applied will remove this problem entirely. May not even be your problem, but have to check every possibility.
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Old 16th December 2012, 05:53 PM   #1044
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Thanks all, and I'll PM you Bob about the board as I'll take it.

I want to try and keep to this version of the board as I've done the casing, plus I would rather start a fresh build to try and eliminate any user errors. I built the boards about 1.5 years ago, however only got around to finishing them now, and I've learnt a lot since then.

Udaily: I've already tried your heat checking method, although what I did was run a song through the working board, but with the "faulty" board connected to the power as well. I then disconnected the power and started by feeling the heat of the components; the LM3886 was hot (not connected to the heat sink for this short period), but that was the only thing that was hot.

From your discussion about the minute scratching, that could well be a possibility, and I'll take that into consideration next time.

Last edited by westers151; 16th December 2012 at 06:01 PM.
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Old 9th February 2013, 11:23 AM   #1045
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Sorry if I missed this... Is there any better opamp that I can use to replace the LM318? I have on hands the 827, 49710 and 1611.
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Old 9th February 2013, 12:18 PM   #1046
bcmbob is offline bcmbob  United States
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Quote:
Originally Posted by lil' knight View Post
Sorry if I missed this... Is there any better opamp that I can use to replace the LM318? I have on hands the 827, 49710 and 1611.
Check out the LF01 thread.
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Old 9th February 2013, 01:34 PM   #1047
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Quote:
Originally Posted by bcmbob View Post
Check out the LF01 thread.
Thanks for the heads-up. Very interesting indeed. Problem is the LF01 still uses the LM318, which is the only component I can't source locally. Just looking for a direct drop-in alternative now.
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Old 9th February 2013, 02:11 PM   #1048
bcmbob is offline bcmbob  United States
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It is your call, but linuxguru can send you a completed unit. That's what I bought. I'll just say it was a most significant upgrade to the MyRef series prior to Dario's Fremen Edition.

I'll also be happy to send you an LM138 via USPS if you wish. The shipping is generally between $4 - $6. PM me if I can help.
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Old 9th February 2013, 02:16 PM   #1049
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Thanks for the offer. Give me a day or two to figure out which is the best for me

I've just skimmed the BOMs... What's the correct value for R2? I see 2 different values, 33k and 10k, from 2 different BOMs. Not sure which is the one to go with. I'm using the v1.2 PCB.
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Old 9th February 2013, 02:40 PM   #1050
bcmbob is offline bcmbob  United States
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Mine is 10K but I don't know if that is optimum. Others may comment.
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