berkleystudios
Well-known member
also in GR i get a terrible hum, but in vu it goes away completely
[BUILD] 1176LN Rev D DIY
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berkleystudios
Well-known member
jplebre said:
no my attack pot is wired fine. just as pictured on mnats site.
here is what is happening now
zeroing my meter does not do anything, although the null adjust is able to zero it out.... (using a trimmer)
it passes audio and compresses when in all buttons in (output drastically increases in this mode). but does not noticeably compress in 4:1 8:1 12:1 or 20:1 (again the vu doesnt really show gr, it does sometimes resemble a ssl meter and will boost the needle forward instead of backwards.
in GR mode i have a terrible hum, when i switch to +4 or +8 the hum goes away completely
finally the output knob when fully clockwise it makes it so i do not have any output even though it should boost my signal correct? i thought i had wired it backwards but ive triple checked it with the mnats pages and it looks to be correct. also when the pot is in any other potion beside fully CW it does not change the level of the signal (could this be a bad pot?)
Echo North
Well-known member
If you just leave it in +4 and GR off is the passed signal good and clean?
Seems like you have a lot of things going on but it may actually be one small thing.
Seems like you have a lot of things going on but it may actually be one small thing.
U87610
Member
Hey fellow DIYers!!
This is my first build, and yes I am using an experienced electrical professional help me safely test the power rails.
We observed 30.4 V AC at the secondaries before testing the power section.
While testing the rails, we got ~ 29.8 V DC for the + rail, and ~ - 9.7 V DC for the - rail. We discharged the capacitors using jumper cables by attaching one clip to the - rail of a capacitor and then touching the other to the chassis. We did this for all four capacitors.
Now testing at home, I tested again (wanted to make sure of consistent values before further populating the board), and got 0.00 V DC at the + rail and - 5.95 V DC at the - rail.
Then I kept getting 0.00 V DC at both and kept frying fuses.
Could I of fried a capacitor discharging it? Or could I have fried the zener diode?
Thanks for your help!!
Attached is a jpeg of my power section.
This is my first build, and yes I am using an experienced electrical professional help me safely test the power rails.
We observed 30.4 V AC at the secondaries before testing the power section.
While testing the rails, we got ~ 29.8 V DC for the + rail, and ~ - 9.7 V DC for the - rail. We discharged the capacitors using jumper cables by attaching one clip to the - rail of a capacitor and then touching the other to the chassis. We did this for all four capacitors.
Now testing at home, I tested again (wanted to make sure of consistent values before further populating the board), and got 0.00 V DC at the + rail and - 5.95 V DC at the - rail.
Then I kept getting 0.00 V DC at both and kept frying fuses.
Could I of fried a capacitor discharging it? Or could I have fried the zener diode?
Thanks for your help!!
Attached is a jpeg of my power section.
Attachments
Echo North
Well-known member
You've got a short or eror somewhere or you are not using slo-blo fuses.
Electrolytic caps, to my knowledge, typically fault to an open circuit rather than a short. However, if you're popping 250mA slo-blo's that's a serious problem.
Can you take it back to your experienced friend? You didn't change anything between your place and his? Are you confident in your testing procedure and meter? Make sure you are testing DC voltage and not current.
Mike
Electrolytic caps, to my knowledge, typically fault to an open circuit rather than a short. However, if you're popping 250mA slo-blo's that's a serious problem.
Can you take it back to your experienced friend? You didn't change anything between your place and his? Are you confident in your testing procedure and meter? Make sure you are testing DC voltage and not current.
Mike
U87610
Member
Thanks for getting back to me so quickly!!
I'm pretty sure that they are slow blow fuses. They also do not blow when I test the secondaries. Also, they are directly from the Mouser rev D catalog. It must be a short somewhere.
The only thing I can think of doing differently is discharging the caps to the chassis. We got the correct values, then discharged the caps. I can take it back to him, though his knowledge is not specific to the 1176 circuitry.
Today I fired it up, got 0.00 V DC at + 30 rail and 5.95 DC at - rail. Then I tested the secondaries. After wiring it back up I did accidentally test (briefly) with the AC setting. Then fuses started to blow. Could I have done some damage then? If so, to which component?
I've been testing from CR6 to -10V and CR6 to +30V
Thanks Mike!!
Even with this setback, this is a terrific project. Thank you and MNats for making the 1176 available to us!!
Could there be a short in one of these traces?
I'm pretty sure that they are slow blow fuses. They also do not blow when I test the secondaries. Also, they are directly from the Mouser rev D catalog. It must be a short somewhere.
The only thing I can think of doing differently is discharging the caps to the chassis. We got the correct values, then discharged the caps. I can take it back to him, though his knowledge is not specific to the 1176 circuitry.
Today I fired it up, got 0.00 V DC at + 30 rail and 5.95 DC at - rail. Then I tested the secondaries. After wiring it back up I did accidentally test (briefly) with the AC setting. Then fuses started to blow. Could I have done some damage then? If so, to which component?
I've been testing from CR6 to -10V and CR6 to +30V
Thanks Mike!!
Even with this setback, this is a terrific project. Thank you and MNats for making the 1176 available to us!!
Could there be a short in one of these traces?
Attachments
Echo North
Well-known member
If you're not blowing fuses until you test the DC side of the circuit, there is something is wrong with your meter or test method. I'm worried you're on the current setting at shorting it, which is very dangerous. If you had a circuit level short, your fuses would blow as soon as you turn the unit on.
I'd get it back to someone with experience and have them look at it, and your test method.
I'd get it back to someone with experience and have them look at it, and your test method.
jplebre
Well-known member
- Joined
- Nov 3, 2012
- Messages
- 617
try and test on the marked spots in the PCB
One right above the big resistor next to the voltage regulator. The other is the zener. Follow the silk screen
I see you have already attached negative side of cap to chassis (the green wire is doing that, right?) If so, make sure your probes are connected to the multimeter on COM (black) and V (red). Put the black probe on the chassis (screw hole will usually do the trick if you scraped the paint off) and probe with the right side, one hand only. Meter should be in DC for these 2 points.
If nothing, you can measure the secondaries of the transformer. Meter should be in AC for these.
One right above the big resistor next to the voltage regulator. The other is the zener. Follow the silk screen
I see you have already attached negative side of cap to chassis (the green wire is doing that, right?) If so, make sure your probes are connected to the multimeter on COM (black) and V (red). Put the black probe on the chassis (screw hole will usually do the trick if you scraped the paint off) and probe with the right side, one hand only. Meter should be in DC for these 2 points.
If nothing, you can measure the secondaries of the transformer. Meter should be in AC for these.
U87610
Member
Mike and Jplebre, Thank you for your posts!!
Mike, regarding testing the secondaries, I meant that I unscrewed them from the circuit, measured them, unplugged the IEC and then reattached them before pluging in the IEC to test the two rails in DC. I am certain that I haven't been using the Current setting, as my multimeter (Ideal 61-340) has it's own specific port for current. I believe that it is shorting when I power the unit on. Could I have shorted something while testing today? I am using the same technique my friend showed me yesterday. Could we have gotten lucky measuring from the grounded side of the zener to the test points yesterday?
I absolutely will be taking it back to my friend, but am trying to pick y'all's brains since you know the troubleshooting aspects of this circuit to see if I need to start over and order a new board from MNats and purchase new power components off of the bill of materials.
Thank you so much for your advice and patience!!
Mike, regarding testing the secondaries, I meant that I unscrewed them from the circuit, measured them, unplugged the IEC and then reattached them before pluging in the IEC to test the two rails in DC. I am certain that I haven't been using the Current setting, as my multimeter (Ideal 61-340) has it's own specific port for current. I believe that it is shorting when I power the unit on. Could I have shorted something while testing today? I am using the same technique my friend showed me yesterday. Could we have gotten lucky measuring from the grounded side of the zener to the test points yesterday?
I absolutely will be taking it back to my friend, but am trying to pick y'all's brains since you know the troubleshooting aspects of this circuit to see if I need to start over and order a new board from MNats and purchase new power components off of the bill of materials.
Thank you so much for your advice and patience!!
U87610
Member
Jplbre,
The grounded green wire is going to the output transformer. As soon as I gather more info, I will test the +30 and - 10 section as you suggested.
Thank you!!
The grounded green wire is going to the output transformer. As soon as I gather more info, I will test the +30 and - 10 section as you suggested.
Thank you!!
U87610
Member
Sorry for the confusion!! Yes, the green wire is grounded to the output transformer chassis, not the transformer itself.
jplebre
Well-known member
- Joined
- Nov 3, 2012
- Messages
- 617
cool so yeah black probe on the chassis.
If you DMM has continuity setting (eg. diode tester) is worth seeing if that cable has continuity with the case and eventually the ground pin on the main plug (unplugged fromt he wall just in case
If you DMM has continuity setting (eg. diode tester) is worth seeing if that cable has continuity with the case and eventually the ground pin on the main plug (unplugged fromt he wall just in case
U87610
Member
Thanks!!
Yes, there is continuity to - lead on Cap C25 and and the case and between - lead on Cap C25 and the IEC ground.
I have been testing individual components before I purchase all of them again. I am not sure how to test my caps using a dmm, but an electronics professional told me that i'd see damage if i fried a cap. Since it's probably not my caps, could it be my linear regulator? For my resistors I have recorded the following values:
R81 0.996 k ohms
R82 0.995 k ohms
R87 1.040 k ohms
R89 218.5 ohms
For my rectifiers:
CR7 --> 0.570 V
<-- .0L
CR8 --> 0.578 V
<-- .0L
CR9 <-- 0.574 V
-->.0L
CR10 <-- 0.572 V
-->.0L
Zener diode
CR6 --> 0.709 V
<-- .0L
I have been trying to test the 7824 linear regulator using a dmm based on a multi step abstract I found online, but am wondering if because mine is in circuit (no power though), the test is inconclusive. Could I still have somehow fried my regulator?
Also, in the previous pictures I uploaded one showing my solder points. To the left of cap C24, there is a nick in the board that penetrates to the trace (not through it). I have continuity all the way to R76 with negligible resistance, but wanted to know if that could possibly cause a short. Thanks!!
Yes, there is continuity to - lead on Cap C25 and and the case and between - lead on Cap C25 and the IEC ground.
I have been testing individual components before I purchase all of them again. I am not sure how to test my caps using a dmm, but an electronics professional told me that i'd see damage if i fried a cap. Since it's probably not my caps, could it be my linear regulator? For my resistors I have recorded the following values:
R81 0.996 k ohms
R82 0.995 k ohms
R87 1.040 k ohms
R89 218.5 ohms
For my rectifiers:
CR7 --> 0.570 V
<-- .0L
CR8 --> 0.578 V
<-- .0L
CR9 <-- 0.574 V
-->.0L
CR10 <-- 0.572 V
-->.0L
Zener diode
CR6 --> 0.709 V
<-- .0L
I have been trying to test the 7824 linear regulator using a dmm based on a multi step abstract I found online, but am wondering if because mine is in circuit (no power though), the test is inconclusive. Could I still have somehow fried my regulator?
Also, in the previous pictures I uploaded one showing my solder points. To the left of cap C24, there is a nick in the board that penetrates to the trace (not through it). I have continuity all the way to R76 with negligible resistance, but wanted to know if that could possibly cause a short. Thanks!!
jplebre
Well-known member
- Joined
- Nov 3, 2012
- Messages
- 617
diodes and resistors are in the ballpark
diodes seem to be working as they should
In fact capacitors you would most likely see it. caps (discharged! and mind polarity for e-lytics) will go towards infinity resistance (eg. set DMM for M-ohms) (might take a few moments to get there)
blowing 7824... possible... but I'll let someone else chime in on that.
cooked trace or lifted pad somewhere? Or something silly like transformer not re-wired properly?
diodes seem to be working as they should
In fact capacitors you would most likely see it. caps (discharged! and mind polarity for e-lytics) will go towards infinity resistance (eg. set DMM for M-ohms) (might take a few moments to get there)
blowing 7824... possible... but I'll let someone else chime in on that.
cooked trace or lifted pad somewhere? Or something silly like transformer not re-wired properly?
Echo North
Well-known member
If you're blowing fuses under load that is troubling. Speaks to an error on the PCB level. Dead voltage regulator? It's possible.
U87610
Member
Thanks for the verifying those values Jplebre and Mike!! I'll test the caps like you suggested Jplebre, and if they're fine according to your test, I'll order a new linear regulator.
then I'll test a few more times, and of I keep popping fuses, I'll purchase a new board and power components.
Thanks again for y'all's help!!
then I'll test a few more times, and of I keep popping fuses, I'll purchase a new board and power components.
Thanks again for y'all's help!!
berkleystudios
Well-known member
Echo North said:
yes the signal is is pristine in +4 and +8 but in GR there is a drastic hum, i keep having to take it to the studio to test and back home to work on it so sorry for the delayed replies.
i think it may be the meter board, i have checked the wiring over and over again but it looks to be correct... is it possible to be a bad pad on the meter pcb?
