[BUILD] 1176LN Rev D DIY

[college101]

OK GUYS!! HELLO!! I got my 1176 rev d all set up....re-checked all my connections, decided to fire it up...

Turned on fine, brought it up slowly on my variac, then put it into GR and set the zero adjust to test the needle movement.
I got the needle to zero out! I was excited at this point!! 

Then, I went to turn the unit off add cable ties to the wires to tidy her up, and turn the 1176 off ..it now will not come back on!?!?!  I checked the fuse, which was fine, and my last few solder connections, everything looks fine!?!? I went back threw the board to see if maybe a cap had blown, or malfunctioning part, nothing seems to be out of order.. nothing looks burned

For info purposes, I checked all values Before I solder'd to the board... I also am using 120 mains, and used the hook up instructions for the Hairball Audio power transformer for 120.

Here's where we start the troubleshooting right!????? 

Start at my A/C connections and work my way back right guys?

 

[college101]

Think I got a lead on it, I believe I have put the transistors with out bending the middle legs to the top triangle hole in the board...I need to de-solder, test,  most likely replace the bad parts and re solder in the correct placement...  Everything else seems to be in order...

Also, can someone clear up the 2k trimmer resistor placements...Ive seen some pics with them facing one way, then the other, and then I see the schematic...  The trimmer resistors wiper pin is in the middle, and the cw pin is under the adjustment knob...AM I correct?

 

[college101]

anybody care to add? Im getting 42 volts AC off the IEC receptacle...ground and blue wire

 

[dandeurloo]

Hey guys.  I have a stereo rev.d I am picking away at.  I have most all of it done but I have run in to a problem.  One of my main boards will not show GR on the meter.  I have done a number of things already and could use a little more help trouble shooting it. Here are the steps I have done so far to narrow down the problem.

1. swapped the 2 boards to confirm that the problem follows the board and not the wiring.  (it follows the board)
2. replaced the fets, and transistors in the sidechain.
3. re-flowed all solder points on the main board.
4. check voltages compared to the voltages schematic.  All voltages seem to be in the right world.
5. check all resistor values against the schematic and all are correct. 

Confirmed working:
Both channels pass audio
+4 portions work on both channels

Any ideas would be great. 

Thanks

 

[college101]

I went threw my board, and I could not locate any blown parts...at first, I thought, maybe I solder'd in the fet's and Transistors wrong,..But I did set them up correctly on the board...My meter looks like it maybe the culprit, and the bulb must be blown as well... Any ideas here guys?  Come on..help a basement electronics guy out

 

[college101]

For the Version 2 PCBs currently being supplied, there are additional footprints for Q5, Q12, and Q13 so 2N5088s can be used in these positions too. This is simply as an added convenience; if you cannot obtain the original transistors or if you happen to have 2N5088 transistors lying around you can use them here. The higher beta isn't required in these positions but won't cause a problem either. Use the alternate base pad between the collector and emitter pads that form a triangle. The inline pads are for the 2N3707/8 devices. Refer to the manufacturer's pinout if you are unsure.

From the Hairball site(see above)

**So with the alternate pads, are the parts going to work the same

I checked every part BEFORE soldering, and verified they were correct part going into the correct location...

 

[dandeurloo]

Bump for my question?

Thanks

 

[college101]

I need help guys, the bulb is still good, I checked with a contnty test on my DMM today, still cant figure it out!  Heres some pics...I hope you guys can help!!

 

[college101]

heres a pic of the bulb and wiring of the power transformer

 

[dandeurloo]

have you confirmed you are getting 30v's and -10 out of your psu?

 

[college101]

Dan- I just checked the Red-black-Red AC pads on the board- im getting 3.5v ac on the red pad

Tell me how to check for the +30 and the -10

 

[dandeurloo]

if you look in the build pdf at the main board markings.  Page 2 in the pdf.  You see an arrow that points to +30v.  You can check there and you can check the -10 the same way.  Its all in the PSU section.  If you don't have those voltages correct that would be the starting point.

 

[college101]

Ok..I found those...In the power supply section..

I need to check for AC, and put the the black probe on the IEC ground while this?

 

[college101]

Identify the two "0V (centre tap)" wires coming from the power transformer secondary. On the Avel-Lindberg power transformer these are the red and orange wires of the secondary windings. Twist them lightly together and secure them in the middle terminal of the terminal strip.

Avel-Lindberg Power Transformer Secondary Terminal Strip Now take the two remaining yellow and black secondary wires and attach them to either end of the terminal strip. The order of the top and bottom wires is unimportant. Just make absolutely sure you have tied the two "0V (centre tap)" red and orange wires together as indicated in Mr. Burnley's illustration.  (From the Avel Transformer page at mnats site)

See ABOVE
Ok, so starting at the top...I think I may have been too trustworthy of the site, and not read my info right off the transformer schematic...  I followed the instructions/pictures above- I put the red and orange wires in the middle of my terminal strip, and have the yellow and black as my direct AC lines....  BUT

After starting over and taking the PT out..I look at the transformer schematic printed on it...

The Black and Orange wires are the 0V center taps, and the Red and Yellow are the 25 volt/0.60A AC lines... Am I missing something here?

 

[college101]

Anybody?

 

[Majestic12]

You have to stick to the schematic printed on the transformer.

 

[college101]

yeah..I just trusted the site more then the info  i thought was right...

 

[college101]

SO I just checked AC coming out of the secondary windings of the PT... and I get .004 volts AC..from each winding...SO I geuss I am buying a new PT from hairball and starting over!

 

[TijuanaKez]

I checked all the resistors in the preamp section by lifting one leg from the board if they didn't measure up in circuit. Everything is as it should be but I still have around 5V on Q3-C and Q14-B and Q14-E, all places where I should be getting 12V. So I decided to start lifting the 2N3391's. I pulled q14 and now Q3-C (and Q14-B solder point) read 12V is they should. Could this mean Q14 is faulty or more likely something downstream from Q14-E?.

They are quite easy to blow up. I'd swap it out and see what happens.

Ok got a whole heap of new 2N3391s from mouser but doesn't fix it. I get correct voltage readings when q14 is not in the board but as soon as I put it in circuit, the 12V that's supposed to be at Q14-B and Q3 both drop to 5V again. Help, its driving me nuts!

 

[college101]

TijuanaKez...I feel you mate...Im going threw the same thing...about to start pulling and replacing every part on the board..if a part is bad, I let everybody know...but for know..Im pretty confused and frustrated with the whole board...