[BUILD] 1176LN Rev D DIY

[Echo North]

I got some new transistors (2n3707) from a shop in town. I swapped a new one into place but the values are exactly the same. Looks like the transistor wasn't the issue but I'm happy I could rule it out.

What is your DCV on each side of R29?

 

[JingleDjango]

21.5VDC > 14.4VDC around R29.

I've checked every resistor on the ratio board, in the preamp and line amp stages and they are the correct values.
All capacitors are oriented as shown in this image: http://www.hairballaudio.com/blog/wp-content/uploads/2013/09/full-PCB.jpg

I started to try and follow continuity from the XLR input and onward. Strangely, the red (+) lead is not making it past the Tpad! I re-flowed  every solder joint on the pad but I still get no continuity from the input + and output + pads on the Bourns PCB. I don't understand why this is. At least I'm learning to troubleshoot independently a bit so that feels good.

 

[Echo North]

21.5VDC > 14.4VDC around R29.

I've checked every resistor on the ratio board, in the preamp and line amp stages and they are the correct values.
All capacitors are oriented as shown in this image: http://www.hairballaudio.com/blog/wp-content/uploads/2013/09/full-PCB.jpg

I started to try and follow continuity from the XLR input and onward. Strangely, the red (+) lead is not making it past the Tpad! I re-flowed  every solder joint on the pad but I still get no continuity from the input + and output + pads on the Bourns PCB. I don't understand why this is. At least I'm learning to troubleshoot independently a bit so that feels good.

The Tpad is maintaining a nominal 500Ω load.  You're ok there.

Are you 100% sure R29 and R30 are the correct value?  What is your voltage at the + side of C10?

 

[JingleDjango]

Brown, Red, Green, Gold. Here's an image. I've been referring to this chart:
http://www.michaels-electronics-lessons.com/images/resistor-color-code-all.gif

C10 is 1uF as indicated.

 

[JingleDjango]

Sorry, here is a hi-res image.

7.1 VDC at the + end of C10

 

[milomofo]

Hey, Ive checked and double checked the solder points and the wiring on the main pcb and on the meter board pcb, So I'm going to go ahead and swap out the transistors one by one. I can source a TO-92 transistor from my local electronics shop, its not going to be the same as the one provided with the kit, but will it be sufficient to use just to check if it is a dodgy tranny?

 

[hymentoptera]

Hey, Ive checked and double checked the solder points and the wiring on the main pcb and on the meter board pcb, So I'm going to go ahead and swap out the transistors one by one. I can source a TO-92 transistor from my local electronics shop, its not going to be the same as the one provided with the kit, but will it be sufficient to use just to check if it is a dodgy tranny?

Not all TO-92 componants are compatiable! There are voltage regulators, bipolar junction transistors, junction field effect transistors, etc, and the majority of those of a given type are NOT compatible with another of the same type. They should be "equivalents" if replacing one part number with another. For instance, the 2n5088 can be the equivalent to 2n3708 in most applications, but their pinout will be different, meaning you must rearrange the componant on the PCB by comparing the datasheets.

Do not swap any old TO-92 part for another unless you understand both parts and how they are similar and how they differ.

 

[hymentoptera]

Sorry, here is a hi-res image.

7.1 VDC at the + end of C10

Just looking at the photo, I would first suspect a solder joint or heat damaged componant. Some of those solder joints are acceptable, but many show signs of too little heat, too much heat, too little solder, or too much solder.

 

[JingleDjango]

That could be the case. Definitely some of the joints have too much solder. I tried when I was doing this to leave at least 20 sec. between joints on the same component.

What components are most likely damaged by overheating? I'm thinking the caps and transistors.

 

[hymentoptera]

Transistors, diodes, ICs, mostly. It takes more to kill film caps, or to lift traces I think, but depends it on many things like quality of manufacture and construction. The trick is just enough heat to get in, add the right amount of solder, and get out. See the EEVBlog videos on youtube, parts 1 and 2 (of 3) for some good soldering tips if you haven't already.

 

[JingleDjango]

https://www.youtube.com/watch?v=vIT4ra6Mo0s
This series was my guide getting into this, before doing a couple of the passive boxes from DIYRE geared at beginners. I'm a novice still and when I finished stuffing the PCB I looked it over and thought that yeah, way too much solder going around.

For joints with too much solder, is it worth my time to clean off the joint with a pump and some wick and re-apply? Or would I be increasing the risk of heat-damaging the parts?

I guess I'll start looking for replacement parts.

 

[JingleDjango]

BTW the new Hairball site looks great.

 

[Echo North]

https://www.youtube.com/watch?v=vIT4ra6Mo0s
This series was my guide getting into this, before doing a couple of the passive boxes from DIYRE geared at beginners. I'm a novice still and when I finished stuffing the PCB I looked it over and thought that yeah, way too much solder going around.

For joints with too much solder, is it worth my time to clean off the joint with a pump and some wick and re-apply? Or would I be increasing the risk of heat-damaging the parts?

I guess I'll start looking for replacement parts.

Ya that could go either way.  If we had it here we'd remove the solder, inspect the pad, then re-solder. Possibly replace the part if it's a semi.  However we have a very nice de-solder station.  Without that I would probably just re-flow. Only remove solder if there was danger of shorting.

Mike

 

[JingleDjango]

Mike, you asked before if CR1 was in the right orientation. It is, but given it's a semi-conducting part of such a small size and in the region where I'm having problems, maybe it's a likely candidate for damage.  I don't know if that's congruent with my issues though, since it follows Q4 and C10 where my readings are already out of whack. So I guess I'll start with some new 2N3391s and see where that takes me. Just brainstorming to myself I guess.  :

I see the flat-rate repair option on the Hairball page and that's tempting but damnit I'm gonna figure this out. Also, I'm broke.

 

[hymentoptera]

If you suspect CR1, then perhaps consider lifting one leg of that diode and test it with the diode setting on your multimeter.

 

[Cardinen]

Hi All,

this is my tribute to this wonderful compressor; everything worked straight from the first power up, perfectly calibrated no hum (-108dB) on both channel.  still missing the stereo link boards, i'll add that later.

Q6 (2n3053) is running very hot so i made these DIY heat sink using a metal sheet, now is much better 

thank to mnats and all the forum to making this possible, this is DIY!

 

[Cardinen]

the front panel (bought from a forum member)

 

[JingleDjango]

hymentoptera, do you think it's necessary to remove CR1 to test it? Testing in the circuit I'm getting a .73V drop from (-) to (+) and nothing passes from (+) to (-). It seems that it's functioning properly.

(Cardinen, I like the purple lamp on your faceplate like the newer UAD units! I'm glad your device worked on the first go. . .)

 

[hymentoptera]

hymentoptera, do you think it's necessary to remove CR1 to test it? Testing in the circuit I'm getting a .73V drop from (-) to (+) and nothing passes from (+) to (-). It seems that it's functioning properly.

Yes, that seems fine. Assuming you have your + and - backwards. Should be one diode drop with the black (COM) lead on the cathode (stripe). We can rule out CR1 I think.

There's a lot of other PN junctions near there, with Q4, Q5, and Q6, and the circuit is a bit of a maze in that section, but if you're measuring 1 diode drop the right way around, and zilch the other, I think you should be good there.

You might even be able to test some of the transistors that way too. All three of those transistors are NPN, so each would look like two diodes "back-to-back" to the diode tester on your multimeter. Can't promise that it will work "in circuit", but you never know.

 

[hymentoptera]

Hi All,

this is my tribute to this wonderful compressor; everything worked straight from the first power up, perfectly calibrated no hum (-108dB) on both channel.  still missing the stereo link boards, i'll add that later.

Q6 (2n3053) is running very hot so i made these DIY heat sink using a metal sheet, now is much better 

thank to mnats and all the forum to making this possible, this is DIY!

A thing of beauty! Everything looks real professional (even the DIY heatsinks ) and I just love these pics of the dual units inside! I hope it sounds as good as it looks. Thanks for sharing.  8)