I have just completed assembling my BOSOZ. It is based on the Colony pcb boards.
The power supply appears to be working I am getting 50volts output.
I connected the preamp to my system and not sound is coming out.
If I turn off the preamp while the CD player is still on I get a some sound bleeding through. With the preamp on no sound.
I would appreciate any advise.
The power supply appears to be working I am getting 50volts output.
I connected the preamp to my system and not sound is coming out.
If I turn off the preamp while the CD player is still on I get a some sound bleeding through. With the preamp on no sound.
I would appreciate any advise.
...hmmm, i can't make much sense of your measurements.
Be very careful taking these measurements! All standard
precautions should be taken.
Measure the Vgs of each FET on the main board. You do this by putting
one probe on the Gate and one on the Source pin. The pin out is
G - D - S as you look at the FET from the front. You should get a
reading like 3.8 or so.
Also, take a measurement at the Drain, like the article says.
This is real easy to do, just put the negative probe of your meter to
ground and the positive on the metal part of the case of each FET.
You should get a reading of 30 volts or so.
You should be getting a reading of 60 Volts at the + and - PSU connection
points on the main board.
All your heatsinks should be toasty warm too!
This is a starting point for toubleshooting.
Good luck, let us know.
Be very careful taking these measurements! All standard precautions should be taken.
Measure the Vgs of each FET on the main board. You do this by putting
one probe on the Gate and one on the Source pin. The pin out is
G - D - S as you look at the FET from the front. You should get a
reading like 3.8 or so.
Also, take a measurement at the Drain, like the article says.
This is real easy to do, just put the negative probe of your meter to
ground and the positive on the metal part of the case of each FET.
You should get a reading of 30 volts or so.
You should be getting a reading of 60 Volts at the + and - PSU connection
points on the main board.
All your heatsinks should be toasty warm too!
This is a starting point for toubleshooting.
Good luck, let us know.
moe29 said:...hmmm, i can't make much sense of your measurements.
precautions should be taken.
Measure the Vgs of each FET on the main board. You do this by putting
one probe on the Gate and one on the Source pin. The pin out is
G - D - S as you look at the FET from the front. You should get a
reading like 3.8 or so.
Also, take a measurement at the Drain, like the article says.
This is real easy to do, just put the negative probe of your meter to
ground and the positive on the metal part of the case of each FET.
You should get a reading of 30 volts or so.
You should be getting a reading of 60 Volts at the + and - PSU connection
points on the main board.
All your heatsinks should be toasty warm too!
This is a starting point for toubleshooting.
Good luck, let us know.
I did some measurements...
Gate to Source was ~3.8
The Drain measurement is 12V
PSU is 20V
The heatsinks are not warm
I checked the PSU and not loose connections. The wiring appears correct. The main board has not loose connections...but I haven't traced out the wiring.
The only posting on the colony boards I found was a mislabeled ZEN amp board.
Concentrate on the PSU. You should be measuring +60, -60 volts under load.
Be sure that you've wired your transformer(s) correctly.
Take a close look at the Zeners. They seem to pop at times. Make sure
the polarity is right on all of them. If in doubt, and you have the parts,
heck replace them all.
Let us know how it goes!
Be sure that you've wired your transformer(s) correctly.
Take a close look at the Zeners. They seem to pop at times. Make sure
the polarity is right on all of them. If in doubt, and you have the parts,
heck replace them all.
Let us know how it goes!
Ok..... after rewiring the transformer on the 120V side I finally got 60v +/-
Still I don't have any output signal. I hooked up a CD player to the preamp and no signal. The interesting thing is if the preamp is turned off while the CD player is still going, the output signal comes on full volume before fading off.
any suggestions?
Still I don't have any output signal. I hooked up a CD player to the preamp and no signal. The interesting thing is if the preamp is turned off while the CD player is still going, the output signal comes on full volume before fading off.
any suggestions?
Are you getting 30 volts on the drains of each FET?
Gates at ground and 3.5 volts or so on the Sources?
If the main board is running right the heat sinks get toasty, along with
the 3 watt resistors.
If you're not using balanced inputs, be sure to ground the Input of
the unused polarity.
If all of that is working right, then recheck how you've wired your
Inputs, Outputs, and Volume Control(s).
There's a lot more places to make a mistake on a preamp then your
normal amplifier - so recheck everything.
Maybe one of the more experienced members could chime in with a
suggestion I think i've reached the limit of what i can suggest,
and don't want to make things harder for you!
Keep working on it, i'm sure we can get this working for you.
Gates at ground and 3.5 volts or so on the Sources?
If the main board is running right the heat sinks get toasty, along with
the 3 watt resistors.
If you're not using balanced inputs, be sure to ground the Input of
the unused polarity.
If all of that is working right, then recheck how you've wired your
Inputs, Outputs, and Volume Control(s).
There's a lot more places to make a mistake on a preamp then your
normal amplifier - so recheck everything.
Maybe one of the more experienced members could chime in with a
suggestion
I think i've reached the limit of what i can suggest,and don't want to make things harder for you!
Keep working on it, i'm sure we can get this working for you.
This never means that I am an expert more experienced.
Anyhow, I would include the following check points:
1. Check whether the 60+ supply line goes through the resistors to Drain of Mosfet.
2. Check whether the 60- supply line goes through the resistors to Source of Mosfet.
3. Check whether the 60- supply line goes through the resistors and comes back to the 60- supply line.
4. Check whether the +/- input lines go through the resistors to Gate of Mosfet.
Good luck.
Happy New Year !!!
Anyhow, I would include the following check points:
1. Check whether the 60+ supply line goes through the resistors to Drain of Mosfet.
2. Check whether the 60- supply line goes through the resistors to Source of Mosfet.
3. Check whether the 60- supply line goes through the resistors and comes back to the 60- supply line.
4. Check whether the +/- input lines go through the resistors to Gate of Mosfet.
Good luck.
Happy New Year !!!
First thanks for the suggestions.
The preamp is still not working. However, I notice that the C3 1000uf cap has deformed (the top of both caps are domed). The caps were installed with the proper polarity. I need to understand what is causing this before replacing them.
Also I doubt that radio shack has these caps in stock, can different value caps be subsituted?
The preamp is still not working. However, I notice that the C3 1000uf cap has deformed (the top of both caps are domed). The caps were installed with the proper polarity. I need to understand what is causing this before replacing them.
Also I doubt that radio shack has these caps in stock, can different value caps be subsituted?
I think reversed polarity can blow a cap, also applying voltage over
the rated spec can do that.
I don't think Radio Shack carries that value. Looks like you'll have to
visit Digikey again. Don't substitute parts, that's one less variable to
worry about.
Be sure you are connecting the - / + side of the PSU output voltage to the
- / + side of the main board. A simple mistake like that can cause problems.
Check to be sure you don't have any solder bridges.
Try to be methodical about your troubleshooting. Like start with the
Power Supply and make sure it's 100% before moving on. Make sure
all the parts on the main board are good. If the caps got blown,
maybe some other parts did too.
Maybe a few days away from the project while waiting for replacement
parts will allow you to see things with a clearer head.
the rated spec can do that.
I don't think Radio Shack carries that value. Looks like you'll have to
visit Digikey again. Don't substitute parts, that's one less variable to
worry about.
Be sure you are connecting the - / + side of the PSU output voltage to the
- / + side of the main board. A simple mistake like that can cause problems.
Check to be sure you don't have any solder bridges.
Try to be methodical about your troubleshooting. Like start with the
Power Supply and make sure it's 100% before moving on. Make sure
all the parts on the main board are good. If the caps got blown,
maybe some other parts did too.
Maybe a few days away from the project while waiting for replacement
parts will allow you to see things with a clearer head.
If fixing your power supply does not solve all your problems, check to see that:
-You placed a wire link across the P5 position(s) on the main board (assuming you are not using P5)
-You have grounded the "-" IN to ground using a small resistor if you are running SE inputs only
-If you have wired the pots in a fashion other than descibed in the article, you might want to try wiring them the way Nelson suggests. Like moe29 said, no need to confuse things by modifying the design at this point.
Pictures might be helpful if you have a digital camera.
-You placed a wire link across the P5 position(s) on the main board (assuming you are not using P5)
-You have grounded the "-" IN to ground using a small resistor if you are running SE inputs only
-If you have wired the pots in a fashion other than descibed in the article, you might want to try wiring them the way Nelson suggests. Like moe29 said, no need to confuse things by modifying the design at this point.
Pictures might be helpful if you have a digital camera.
Raoul said:
Thank you for the suggestions
What do you mean by "SE inputs"
I have looked over the boards and nothing appears to be incorrect.
I do agree with you and Moe29....attached is the diagram where I attached the pots ( by a suggestion of someone at the forum). I am now wondering if this is causing my problem. What do guys think??
The pot is a dual gang 10K and there is a 1K resistor on one leg.
Attachments
That's not the correct position for the pots. You need to change that.
SE = Single Ended. Your normal RCA inputs are single ended.
The BZLS schematic shows Balanced Inputs and Balanced Outputs.
You can use a Single Ended Input you just need to ground the - input.
The reason you do that is with a single ended input you only use
the + and Ground. With a Balanced input you would use the -, +, and G.
So since you're not using the - side you ground it instead of letting it float.
Now concerning the proper placement of your pots... The BZLS isn't
like most preamps, it's very versitile. It's set up for attenuation at the
Inputs, Outputs, and a spot for overall gain. (P5) Nelson's article
explains the utility of having each of these a lot better than i could.
If you just want to use one Pot, put it at the output.
If you're going to use this preamp as Single Ended Input and Single
Ended Output, you loose a bit of it's performance capability.
I can't really explain how to wire your pot to attenuate a single
ended output, since i use it with Balanced outputs...
I'm sure someone else will help if this is the case.
(and correct my explanation if any of the above is wrong!)
keep plugging away, you can do it!
SE = Single Ended. Your normal RCA inputs are single ended.
The BZLS schematic shows Balanced Inputs and Balanced Outputs.
You can use a Single Ended Input you just need to ground the - input.
The reason you do that is with a single ended input you only use
the + and Ground. With a Balanced input you would use the -, +, and G.
So since you're not using the - side you ground it instead of letting it float.
Now concerning the proper placement of your pots... The BZLS isn't
like most preamps, it's very versitile. It's set up for attenuation at the
Inputs, Outputs, and a spot for overall gain. (P5) Nelson's article
explains the utility of having each of these a lot better than i could.
If you just want to use one Pot, put it at the output.
If you're going to use this preamp as Single Ended Input and Single
Ended Output, you loose a bit of it's performance capability.
I can't really explain how to wire your pot to attenuate a single
ended output, since i use it with Balanced outputs...
I'm sure someone else will help if this is the case.
(and correct my explanation if any of the above is wrong!)
keep plugging away, you can do it!
By SE inputs, I mean single ended, RCA-type connector inputs. When you use RCA inputs only (and no XLR balanced inputs), you will connect the pin of the RCA connector to the "+" in on the main board, and the ground of the RCA connector to one of the many GND holes available on the main board. An XLR type balanced connector will have three pins: a positive pin (connects to the "+" input on the mainboard), a ground pin (connects to the GND on the main board), and a negative pin (connects to the "-" input on the mainboard). Since RCA connectors lack this third pin, you end up with nothing attached to the "-" input (note: don't hook the RCA connector ground up here). Something needs to be hooked up to the "-" input. A 221 ohm 1/4W resistor can be used to connect the "-" input to one of the GND inputs on the main board. That's it. If you use a balanced XLR-type connector in the future, you can simply remove the resistor and wire the XLR in as per the directions in the BZLS instructions.
I have some pictures of the "-" input to GND resistor that I described above. Unfortunately they are too large to post here. I can email them to you if you would like.
edit: looks like moe29 beat me to the punch...
I have some pictures of the "-" input to GND resistor that I described above. Unfortunately they are too large to post here. I can email them to you if you would like.
edit: looks like moe29 beat me to the punch...
I appreciates the replies
Raoul yes please email me the additional information--email address kennethrl@email.com
So what your suggestion on the ohm rating for the output pot?
I have a Leich Amplifier and a Yamaha CD player. Is there a way to make them balanced inputs?
Raoul yes please email me the additional information--email address kennethrl@email.com
So what your suggestion on the ohm rating for the output pot?
I have a Leich Amplifier and a Yamaha CD player. Is there a way to make them balanced inputs?
I use a 10K attenuator at the output. I think the article suggests 5K, but 10K works fine for me. I wired the + OUT from the board to the IN on the attenuator. I wired the OUT of the attenuator to the pin of the output RCA. I then wired the attenuator GND to the RCA ground tab. May be a better way to do it, but that works for me.
Not sure about the balanced output modifications for the other pieces. I would imagine someone has asks that same question about the Leach amp. Rod Elliot probably has a SE to balanced circuit on his website. I run my BOSOZ single ended and it sounds pretty darn good, though.
I sent the pic to your email.
Not sure about the balanced output modifications for the other pieces. I would imagine someone has asks that same question about the Leach amp. Rod Elliot probably has a SE to balanced circuit on his website. I run my BOSOZ single ended and it sounds pretty darn good, though.
I sent the pic to your email.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.