[BUILD] 1176LN Rev D DIY

[offthewallstudio]

I don't mean to offend anyone. But is OFFTHEWALLSTUDIO for real, or is this a pal of Mike's trying to find out how far he can go before Mike figures out the joke???

If he's for real, put me down for participating in a fund raising drive which would refund  OFFTHEWALLSTUDIO the cost of his kit, plus $50 for the effort.

I'm down for $10 and mean not to offend anyone. OFFTHEWALLSTUDIO seems like he could hurt himself with his kit... and my motive is selfish; I want to be able to buy Hairball kits in the future.

im for real yes. I want to be safe so i am asking alot of questions.  I finally successfully built the power supply.  Mike has been great with helping.... im good to go from here...

 

[Echo North]

I checked pad 7 with the cable removed and it is 0 volts.  The CW lug on the pot reads 11 and some volts.

sorry Mike, I was referring to the attack pot cw lug wired to pad 7.

That's not possible if wired correctly.  Triple check that wiring 18/19/7.  If that is all correct I'm just stumped.  Pad 28/29 are beside pad 7 and they have 10V DC.  I wonder if there is a mechanical issue in that terminal block causing issues?  Maybe try disconnecting 28/29 and seeing if 7 reads properly.

Mike

 

[jonesey013]

Hello friends,

I am working on the power supply section of the Rev D. build, and found that I had ordered the wrong wattage of the 1.1K resistor (it was 1/4 watt instead of 1 Watt). Unfortunately, the 1.1K/1W resistor appears to be a difficult part to source from Canada (where I am), so I am stuck with either getting the 1 resistor from mouser or similar (which will take time and be expensive), or getting something similar. I found a 1.2k/1W resistor locally.

My question is whether the 1.2k/1W would be an acceptable substitution, or whether the resistance values are crucial at that point of the circuit. I realize as well that it sits at a measurement point, so perhaps getting that exact value is important.

Thank you in advance for your help!

 

[Harpo]

Unfortunately, the 1.1K/1W resistor appears to be a difficult part to source from Canada ...

Two 2.2k/0.5W resistors in parallel in order to substitute the 1.1k/1W resistor might be easier to source ...
Your 1.2k/1W substitute will cause the output voltage to drop by about 0.4VDC to 29.4VDC.
Ignoring parts tolerances and 7824 vreg. Ib typ.4.6mA, Vout=24V*(1+220R/1100R)+220R*0.0046A, giving 29.8VDC.

 

[jonesey013]

Wow, great answer, thank you Harpo!

 

[mnats]

I checked pad 7 with the cable removed and it is 0 volts.  The CW lug on the pot reads 11 and some volts.

Which pot do you mean here.  Attack or Release?

sorry Mike, I was referring to the attack pot cw lug wired to pad 7.

Please measure the voltage across the Attack pot, then across the Release pot with both controls fully CCW. If there is really ~13 volts across the release pot it would be interesting to know why. Measure with one probe on each outside lug.

 

[bxershrts]

I checked pad 7 with the cable removed and it is 0 volts.  The CW lug on the pot reads 11 and some volts.

sorry Mike, I was referring to the attack pot cw lug wired to pad 7.


That's not possible if wired correctly.  Triple check that wiring 18/19/7.  If that is all correct I'm just stumped.  Pad 28/29 are beside pad 7 and they have 10V DC.  I wonder if there is a mechanical issue in that terminal block causing issues?  Maybe try disconnecting 28/29 and seeing if 7 reads properly.

Mike


Hello,

Ok.....

With 28 and 29 removed I read

Pad 29 (-0.359)
Pad 28 (0.584)

With 28 and 29 connected I read

Pad 29 (0.565)
Pad 28 (0.585)

I checked pad 7 with the cable removed and it is 0 volts.  The CW lug on the pot reads 11 and some volts.

Which pot do you mean here.  Attack or Release?

sorry Mike, I was referring to the attack pot cw lug wired to pad 7.


Please measure the voltage across the Attack pot, then across the Release pot with both controls fully CCW. If there is really ~13 volts across the release pot it would be interesting to know why. Measure with one probe on each outside lug.

I read 14.84 vdc on the release pot
I read 0.274 vdc on the attack pot


With 28 and 29 removed I read 12.83vdc @ pad 7
With 28 and 29 connected I read the same 12.83 volts at pad 7

I have checked my wiring against the other builds that are working. I have checked the resistors on the Ratio Board and all the solder terminals. I am stuck for ideas now...?

 

[EmptyMusicBox1]

My 1176LN RevD  1U FINISH :

Serigraphie

 

[bxershrts]

Mike and Mnats :

I have been measuring the board,  and disconnected pads 20 thru 19. I measured continuity between each of them and found that pad 18 and the one next to it (ground)  are connected.  18 being a leg of the q bias pot and the one to its right (toward center)  the ground are showing continuity.  I have done this chasing the idea that mechanically, the terminals are connected.  Could this be my problem?

 

[Echo North]

Mike and Mnats :

I have been measuring the board,  and disconnected pads 20 thru 19. I measured continuity between each of them and found that pad 18 and the one next to it (ground)  are connected.  18 being a leg of the q bias pot and the one to its right (toward center)  the ground are showing continuity.  I have done this chasing the idea that mechanically, the terminals are connected.  Could this be my problem?

Definitely.  18 and Ground should not have continuity or low resistance.  You need to figure out why that is happening. 

 

[mnats]

Could this be my problem?

It could be one problem but it does not explain where the 14.84 Volts across the release pot is coming from. If I haven't been clear that's the main issue you need to sort out.

 

[bxershrts]

Good morning.  Well,  i did find one problem.  The q bias pot i used was shorted across the wiper.  Thinking i had found the solution,  i put the pcb back in and still have big volts across the release pot.  I have checked then rechecked had friends come and check and all the wiring is the same as the other ones that are working.  Could possibly a capacitor in c22, c6 and c3 be leaking creating such a voltage spike? 

Thanks for you ideas and help

 

[bxershrts]

PROBLEM SOLVED !

With the help of a few great minds , Mnats and Mike I have found the problem. 

Problem 1 : Q bias pot was open, all signal went to ground.(connecting pad 18 and GND)

Problem 2 : C6 was absolutely leaking. Capacitor Changed and now there is no voltage at Release pot or attack pot.

I am able to get great signal to output and all trim pots function as they should. Although I will have to change R44 to 5k to get more swing for adjustment.

Thanks again guys for your ideas to help!

 

[mnats]

Problem 2 : C6 was absolutely leaking. Capacitor Changed and now there is no voltage at Release pot or attack pot.

I'm happy you've fixed your problem, but if you had 14 volts at the gate of Q1 and a leaking ceramic or mica capacitor that imposed that voltage on the release pot then you'd still have a problem. I suspect that something you've disturbed during troubleshooting has removed the voltage. Simple test - measure the voltage at the gate of Q1 now.

 

[offthewallstudio]

[quote aut @ pad 7[/color]
[/quote]

Mike
[/quote] Hi Mike. Question. I think the kit was mmissing a few resistors r9 560k and r28 27k
i have 13 other resistors left over. Pls see photos.

 

[offthewallstudio]

[quote aut @ pad 7[/color]

Mike
[/quote] Hi Mike. Question. I think the kit was mmissing a few resistors r9 560k and r28 27k
i have 13 other resistors left over. Pls see photos.
[/quote] more photos

 

[Echo North]

[quote aut @ pad 7[/color]

Mike

Hi Mike. Question. I think the kit was mmissing a few resistors r9 560k and r28 27k
i have 13 other resistors left over. Pls see photos.
[/quote] more photos
[/quote]

That's really weird.  We'll send you the missing parts but check the rest of the parts (capacitors) first to see if you're missing anything else.

You have a lot of cold looking joints.  Try to use a little less solder.

 

[offthewallstudio]

[quote aut @ pad 7[/color]

Mike

Hi Mike. Question. I think the kit was mmissing a few resistors r9 560k and r28 27k
i have 13 other resistors left over. Pls see photos.

more photos
[/quote]

That's really weird.  We'll send you the missing parts but check the rest of the parts (capacitors) first to see if you're missing anything else.

You have a lot of cold looking joints.  Try to use a little less solder.
[/quote] Thanks Mike and i will keep at it once it is stuffed ill get back to you. the photo i have will all the resistors do any of those look foreign to this build? For the cold solder do you think this will cause me a problem? i wonder if it is the flash or the photo that makes them look bad? Thanks!

 

[weiss]

i wonder if it is the flash or the photo that makes them look bad? Thanks!

it looks like you soldered the parts on the top side of the pcb. i'd also try using less solder

 

[jonesey013]

Hello,

I just completed the Rev. D. Before I plugged it in, I rechecked polarity on all polarized components, checked for solder bridges, then went through the entire wiring guide again to make sure everything was wired correctly. I had previously checked my power supply, and it provided voltage at the test points within range.

I turned it on, and the meter lamp came on and I ran a 1khz signal through the input. The unit was receiving signal fine and the knobs seemed to work. Then, all of a sudden the light went out and it stopped working completely.

I checked my fuse, and it appears intact. I then re-measured the DC voltages (+30DC and -10DC), but I am now not getting any DC at all at the test points.

One thing that I did which could possibly have caused issues, is that in completing the meter lamp wiring, I connected the meter lamp circuit wires to the terminal blocks for the power transformer secondary. I did this because I did the build without a terminal strip for the transformer secondary, and connected the secondary wires right to the PCB terminal strip.

Knowing (and accepting) that I have probably made some stupid error somewhere along the way, does anybody have any insight about what could have happened, and where I should start looking for problems?

Thanks in advance!