2 minute video question
- Thread starter ReRibbon
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Help Support GroupDIY Audio Forum:
Humner
Well-known member
the problems you are having, did they exist before you recapped the board?
If they didn't, then you need to go through and check your soldering.
Power up each section on its own - for example, power up a single master channel - does it work fine? If yes, then power up the next master channel, and then the inputs etc. You need to isolate the problem. One thing to note is that both VU's are pegging so you could assume that the issue is my not be isolated to a single master channel etc.
Does it pass audio? Is there a loud hum getting through? Check for excessive DC in the audio path.
So many things to consider, you need to isolate the problem before we can begin to help otherwise we will be guessing for weeks.
If they didn't, then you need to go through and check your soldering.
Power up each section on its own - for example, power up a single master channel - does it work fine? If yes, then power up the next master channel, and then the inputs etc. You need to isolate the problem. One thing to note is that both VU's are pegging so you could assume that the issue is my not be isolated to a single master channel etc.
Does it pass audio? Is there a loud hum getting through? Check for excessive DC in the audio path.
So many things to consider, you need to isolate the problem before we can begin to help otherwise we will be guessing for weeks.
Since you did several topics on improving that desk it's hard to guess.
Back to beginning, for what did you changed - you can do the list of it here.
If you have an option to trace connected channel, put 1kHz sine wave and trace the signal in audio path, sooner or later you will find the dead spot. Check all connectors between modules - for good orientation etc.
There could be even a broken wire anywhere.
Back to beginning, for what did you changed - you can do the list of it here.
If you have an option to trace connected channel, put 1kHz sine wave and trace the signal in audio path, sooner or later you will find the dead spot. Check all connectors between modules - for good orientation etc.
There could be even a broken wire anywhere.
@ Hummer
No, 7 of 8 worked but not well. I looked inside and there were a bunch of blown caps. Will check here in a minute.
I'll try that. All channels are chained /tethered together so separately powering them might be tricky.
It does not pass audio. No hum no nothing. How do I check for too much DC?
Its only day one!
@In76d
All ive changed are the electrolytic capacitors. Value for value matched. Polarity triple checked before installing. Power section included. About 100 caps all together.
Also swapped op amps from 833n to 5532's.
Thats all. Nothing else.
I've worked so hard on this damn thing..... DAMMIT
No, 7 of 8 worked but not well. I looked inside and there were a bunch of blown caps. Will check here in a minute.
I'll try that. All channels are chained /tethered together so separately powering them might be tricky.
It does not pass audio. No hum no nothing. How do I check for too much DC?
Its only day one!
@In76d
All ive changed are the electrolytic capacitors. Value for value matched. Polarity triple checked before installing. Power section included. About 100 caps all together.
Also swapped op amps from 833n to 5532's.
Thats all. Nothing else.
I've worked so hard on this damn thing..... DAMMIT
What's the console brand/model?
How much opamp did you swapped?
Check PSU DC voltage between pin 4 and ground and pin 8 and ground on ne5532.
W need too check also that there's no current limiting resistors in the opamp supply.
NE5532 can suck current twice than LM833N
Did you use DIP8 sockets for opamps?
Could you make some photos of you soldering?
Still 1kHz sine wave could be good option to see what happened.
DC offset between pin 1 and ground on opamp - try 2V DC range on your meter, if it's lower change to the 200mV.
How much opamp did you swapped?
Check PSU DC voltage between pin 4 and ground and pin 8 and ground on ne5532.
W need too check also that there's no current limiting resistors in the opamp supply.
NE5532 can suck current twice than LM833N
Did you use DIP8 sockets for opamps?
Could you make some photos of you soldering?
Still 1kHz sine wave could be good option to see what happened.
DC offset between pin 1 and ground on opamp - try 2V DC range on your meter, if it's lower change to the 200mV.
Ok. So using a fluke 77 399mV setting, the reading from pin 4 to ground on one channel was 43 and slowly rose to 43.5. On another channel, it read 44 and slowly climbed to 44.3.
Pin 1 and ground of the 5532 reads on one channel +2.0 but on another channel it reads -2.1. Whats up with that? :/
I swapped 8 opamps. All 5532's in place of 833n's. Each channel has 4 opamps total. The 5532 is the first and is rihgt behind the gain pot. The next one is a TL0171cp behind the treble eq pot. Then a TL072(B or D) behind the mid pot sweep, and finally an L8136 behind the bass eq pot.
Brb
Pin 1 and ground of the 5532 reads on one channel +2.0 but on another channel it reads -2.1. Whats up with that? :/
I swapped 8 opamps. All 5532's in place of 833n's. Each channel has 4 opamps total. The 5532 is the first and is rihgt behind the gain pot. The next one is a TL0171cp behind the treble eq pot. Then a TL072(B or D) behind the mid pot sweep, and finally an L8136 behind the bass eq pot.
Brb
First! What's the console brand and model?
Did you measured DC voltage? These you should measure on 20V (or higher) range.
4mV between Pin 4 and ground? It should be -12V, -15V, -18V etc.
Conclusions are as follows - you have single supply or damaged PSU or you didn't measure reffered to ground...
What about pin 8 / ground?
You can also measure between pin 4 and 8.
Here you have right pinout for a dual opamp;
http://www.planetz.com/wp-content/uploads/2013/08/TL072-Op-amp1.png
Did you measured DC voltage? These you should measure on 20V (or higher) range.
4mV between Pin 4 and ground? It should be -12V, -15V, -18V etc.
Conclusions are as follows - you have single supply or damaged PSU or you didn't measure reffered to ground...
What about pin 8 / ground?
You can also measure between pin 4 and 8.
Here you have right pinout for a dual opamp;
http://www.planetz.com/wp-content/uploads/2013/08/TL072-Op-amp1.png
Just measured dC from ground to both pins 4 and 8 of the 5532 op amps.
Ground to pin 4 reads on average -14.43 on each of the 8 channels.
Ground to pin 8 reads on average +17.05 with the exception of channels 1 and 2. Chn 1 read +16.81 and chm 2 read +12.43. As i was finishing up with these readings, a resistor on channel 2 started to smoke... so I unplugged the board.
Here is a photo of exact measurements.
To answer the previous question, the board is obscure. Location model was made by a British company in the early 80's called Oxglade Ltd. Apparently they were neighbors with Neve or something. It has the same brand transformers as was being used by Neve at that time, stepped eq pots, etc. I think it's some kind of clone or something. Sounds really good when working.
Ground to pin 4 reads on average -14.43 on each of the 8 channels.
Ground to pin 8 reads on average +17.05 with the exception of channels 1 and 2. Chn 1 read +16.81 and chm 2 read +12.43. As i was finishing up with these readings, a resistor on channel 2 started to smoke... so I unplugged the board.
Here is a photo of exact measurements.
To answer the previous question, the board is obscure. Location model was made by a British company in the early 80's called Oxglade Ltd. Apparently they were neighbors with Neve or something. It has the same brand transformers as was being used by Neve at that time, stepped eq pots, etc. I think it's some kind of clone or something. Sounds really good when working.
Attachments
So am guessing that there's no any schematic...
Verify all work that you did on first and second channel. All connections to the both modules and look for cold joints, that you could made.
Did you used dip sockets or soldered opamps to the board?
Did you recapped PSU? Could you make good resolution photo of power supply.
Check with the finger NE5532 case on any channel. Is it hot?
Verify all work that you did on first and second channel. All connections to the both modules and look for cold joints, that you could made.
Did you used dip sockets or soldered opamps to the board?
Did you recapped PSU? Could you make good resolution photo of power supply.
Check with the finger NE5532 case on any channel. Is it hot?
Unfortunately, no schematic...
Im about to remove these two channels here in a second and verify.
Channel 1 has a dip socket for the 5532. Channel 2 is straight soldered. Its' dip socket was broken and i didnt have another one. The rest of the op amps are all factory soldered directly as well.
Yes, PSU was recapped. Photo from the top is attached. Will have to remove to photograph tge underside.
Would it be ok to plug the board back on to feel the opamps?
The resistor that smoked reads 26.7 ohm, but all of the ither resistors in the same positiin on each channel read 27 ohm. This position is in between pin 4 of all op amps and pin 1 of the +(?)power source cable which links the pSU and the board. It is the blue cable on the bottom left in the photo on the bottom connectors.
Im about to remove these two channels here in a second and verify.
Channel 1 has a dip socket for the 5532. Channel 2 is straight soldered. Its' dip socket was broken and i didnt have another one. The rest of the op amps are all factory soldered directly as well.
Yes, PSU was recapped. Photo from the top is attached. Will have to remove to photograph tge underside.
Would it be ok to plug the board back on to feel the opamps?
The resistor that smoked reads 26.7 ohm, but all of the ither resistors in the same positiin on each channel read 27 ohm. This position is in between pin 4 of all op amps and pin 1 of the +(?)power source cable which links the pSU and the board. It is the blue cable on the bottom left in the photo on the bottom connectors.
Attachments
Are there similar resistors from pin 8 to -V point?
These are probably current limiters, if so - you could try remove it and place jumper instead (or 0ohm resistor).
Check first is there any of 5532 hot, it's common with current limiters.
If you can, check unloaded PSU output voltages.
These are probably current limiters, if so - you could try remove it and place jumper instead (or 0ohm resistor).
Check first is there any of 5532 hot, it's common with current limiters.
If you can, check unloaded PSU output voltages.
Pi 8 of the 5532 goes straight to an electrolytic cap.
Plugged the board back in for about a minute. Op amps werent warm but that resistor didnt smoke either.
Unloaded current.....
How is that checked please? Use resistance on tge meter? Vdc?
Plugged the board back in for about a minute. Op amps werent warm but that resistor didnt smoke either.
Unloaded current.....
How is that checked please? Use resistance on tge meter? Vdc?
Hmm... It's getting started to be complicated, so you need find some solution to make it easier...
We don't have schematic, there's hard to judge anything from what you write etc.
Maybe you could post photos of one channel and mark which resistor is burnt, where's the capacitor after pin 8?
We can make hundred more posts like all previous, but it can change anything...
Electrolytic capacitor after pin 8 doesn't change anything, because probably it's refered to ground, so you can look after that, is there any resistor going to +V PSU. You can start looking from the PSU side.
I've found some photos in previous topics and i don't see 27ohm resistor.
Check by color code what's the value. Here's something useful:
http://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-resistor-color-code-4-band
Measuring resistance in the circuit have no sense at all.
Disconnect whole secondary side of PSU, and measure all DC Voltages on each connector.
Also, on the PSU board you have three the same connectors, are you sure that you didn't change the proper cables order by mistake?
To get hot opamp you will need a little bit more time than one minute.
We don't have schematic, there's hard to judge anything from what you write etc.
Maybe you could post photos of one channel and mark which resistor is burnt, where's the capacitor after pin 8?
We can make hundred more posts like all previous, but it can change anything...
Electrolytic capacitor after pin 8 doesn't change anything, because probably it's refered to ground, so you can look after that, is there any resistor going to +V PSU. You can start looking from the PSU side.
I've found some photos in previous topics and i don't see 27ohm resistor.
Check by color code what's the value. Here's something useful:
http://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-resistor-color-code-4-band
Measuring resistance in the circuit have no sense at all.
Disconnect whole secondary side of PSU, and measure all DC Voltages on each connector.
Also, on the PSU board you have three the same connectors, are you sure that you didn't change the proper cables order by mistake?
To get hot opamp you will need a little bit more time than one minute.
Yes, the 5532 on channel 2 was warm. The caps next to it were as well. This is the channel that had the smoking resistor. The rest were not hot at all.
So ive checked and tightened the solder joints up on both channels 1 and 2;the results were that the DC voltage from pin 4 op amp now reads -15.85 and on pin 8, reads +16.41.
VU meters are still spiked and still no audio signal passes.
So ive checked and tightened the solder joints up on both channels 1 and 2;the results were that the DC voltage from pin 4 op amp now reads -15.85 and on pin 8, reads +16.41.
VU meters are still spiked and still no audio signal passes.
ReRibbon said:
LN76D wrote "100nF"
I think he meant a 0.1uF cap from V+ (and V-) of the 5532s to ground to prevent noice and oscillations.
