Well a closer look and the photos don't match the schematic. For one, the photo has 2 output devices per side vs schematic which has 3. More importantly, the schematic says signal is on pin5 and signal ground is on pin 4. The photo shows signal on pin 5 and signal ground on pin 3.
Can you post a diagram of how you've wired the input jack, PSU & speaker terminals
It's not looking good for the 2x board
Can you post a diagram of how you've wired the input jack, PSU & speaker terminals
It's not looking good for the 2x board
I know that my amp boards are different than the ones in the schematic (so is my PSU), since the schematic is for an AVR-307 (mine's a jazzed up AVR-202), but I think that they are similar enough to apply the same sort of operations. I read the info you suggested for the schematic, and tried to adjust it slightly to match my boards. I can work on a diagram, but I've got to find a suitable program first. What are some popular ones?
For now, I'll just explain it simply:
I connected to each module, the red/black/orange power cable, the red output cable, and the green ground cable.
I then ran wires from each signal ground (pin 3) to the main amp ground.
Finally I ran a wire from the row of CTRL leads on the PSU to the main amp ground.
I tested the resistance from each "pin 3" and each CTRL lead to the main amp ground to make sure that it was zero.
When I was testing the signal input, I connected the RCA jack of the source like so: Inner pin to pin 5 on the amp input. Outer sleeve to pin 3 on the amp input (which was also connected to GND).
For now, I'll just explain it simply:
I connected to each module, the red/black/orange power cable, the red output cable, and the green ground cable.
I then ran wires from each signal ground (pin 3) to the main amp ground.
Finally I ran a wire from the row of CTRL leads on the PSU to the main amp ground.
I tested the resistance from each "pin 3" and each CTRL lead to the main amp ground to make sure that it was zero.
When I was testing the signal input, I connected the RCA jack of the source like so: Inner pin to pin 5 on the amp input. Outer sleeve to pin 3 on the amp input (which was also connected to GND).
. I couldn't quickly spot any burns on the amp or any of its components, but I can look more closely. Is it easy to identify a burned resistor?Zep, I'll also email you the schematic for the B&K AV-5000 amp. That amp section may be more similar to the 202 amp section.
I also thought the 307 had 4 output devices on each side and one isn't used. (7-channel.) The 202 should have 3 on one side and two on the other. The 5000 has 3 on one side and two on the other (5-channel.)
I also thought the 307 had 4 output devices on each side and one isn't used. (7-channel.) The 202 should have 3 on one side and two on the other. The 5000 has 3 on one side and two on the other (5-channel.)
An externally hosted image should be here but it was not working when we last tested it.
As an aside, one can see the B&K design lineage over the years:
Starting from the Av-5000 (used one 2x60w and one 3x105 amp board)
AV-5000II (used one 2x105w and one 3x105 amp board)
AV-6000 (used two 3x105 amp boards)
Ref. series preamps (ref. 20, 30, 50, 70)
AVR-202 (seems like same amp section as the AV-5000II but a receiver with a ref. 20 preamp inside)
AVR-202i (same as AVR-202 but with component video)
AVR-307 (7-channel with component video, w/ref. 30 preamp inside)
AVR-507 (7-channel with component video, w/ref. 50 preamp inside)
AVR-707 (7-channel with HDMI, w/ ref. 70 pre-amp)
in between there are the ref. 125.x and ref. 200.x amps, where the x indicates the number of channels.
Starting from the Av-5000 (used one 2x60w and one 3x105 amp board)
AV-5000II (used one 2x105w and one 3x105 amp board)
AV-6000 (used two 3x105 amp boards)
Ref. series preamps (ref. 20, 30, 50, 70)
AVR-202 (seems like same amp section as the AV-5000II but a receiver with a ref. 20 preamp inside)
AVR-202i (same as AVR-202 but with component video)
AVR-307 (7-channel with component video, w/ref. 30 preamp inside)
AVR-507 (7-channel with component video, w/ref. 50 preamp inside)
AVR-707 (7-channel with HDMI, w/ ref. 70 pre-amp)
in between there are the ref. 125.x and ref. 200.x amps, where the x indicates the number of channels.
Yeah, this weekend kinda halted everything didn't it
The bad amp needs to have some failure analysis performed before you go ahead and power up the good amps.
When you measured 40V on the output, were the rails still at ±65V? If the rails are being pulled down to 40V then there is some serious current flowing. If the rails are at 65V and the o/p is 40V then it's just something open/dead in the feedback loop.
You'll need to pull the output transistors and the driver transistors (Q1, Q8) off the PCB and check for b-e and b-c diode function.
I'd check Q4 & Q5 as well but then I'm paranoid
The bad amp needs to have some failure analysis performed before you go ahead and power up the good amps.
When you measured 40V on the output, were the rails still at ±65V? If the rails are being pulled down to 40V then there is some serious current flowing. If the rails are at 65V and the o/p is 40V then it's just something open/dead in the feedback loop.
You'll need to pull the output transistors and the driver transistors (Q1, Q8) off the PCB and check for b-e and b-c diode function.
I'd check Q4 & Q5 as well but then I'm paranoid
I did test the rail voltage; it was steady at +/- 65V with all 5 amp modules attached. The three channel board read 0V at the speaker terminals, and the two channel board read about 36V at the speaker terminals.
Here's a question for ya. What's the best way to pull these transistors from the board? Because they have three terminals, it's difficult to unsolder each terminal individually. If there were only two, like on caps and resistors (ect), I could pull one and then the other but more makes it hard. I had the same issue with the bridge rectifiers I (tried) to replace earlier. They had 4 terminals in-line. Any words of wisdom here?
Here's a question for ya. What's the best way to pull these transistors from the board? Because they have three terminals, it's difficult to unsolder each terminal individually. If there were only two, like on caps and resistors (ect), I could pull one and then the other but more makes it hard. I had the same issue with the bridge rectifiers I (tried) to replace earlier. They had 4 terminals in-line. Any words of wisdom here?
desoldering wick/braid (forget the suckers )
Even on through-hole plated boards you can usually get 1 of 3 loose then heat one, work loose etcetc. Sometimes if you can't get the last picoliter of solder out, lightly re-soldering the joint will allow some fresh wick to get it clean (kinda non-intuitive but it's the flux that helps)
I usually apply the wick 1" in from the end, then I can pull fresh wick through the joint after it melts. I use the iron to apply pressure on the wick against the solder joint. The fresh wick maintains the capillary action sucking the solder up. It's a PITA but cut the used wick off every time.
Desoldering wick is very hard on your iron tips. Reapply fresh solder to the iron tip to stop it oxidizing and getting all pitted.
Practice on a junk board before working on valuable stuff.
)Even on through-hole plated boards you can usually get 1 of 3 loose then heat one, work loose etcetc. Sometimes if you can't get the last picoliter of solder out, lightly re-soldering the joint will allow some fresh wick to get it clean (kinda non-intuitive but it's the flux that helps)
I usually apply the wick 1" in from the end, then I can pull fresh wick through the joint after it melts. I use the iron to apply pressure on the wick against the solder joint. The fresh wick maintains the capillary action sucking the solder up. It's a PITA but cut the used wick off every time.
Desoldering wick is very hard on your iron tips. Reapply fresh solder to the iron tip to stop it oxidizing and getting all pitted.
Practice on a junk board before working on valuable stuff.
I'll be practicing on some of the processing boards (desoldering using the wick) for a bit more before I move to the amp modules. Should I pull ALL of the MOSFETs, the driver trans, and the other ones (Q4/Q5) from the board? What kind of readings should I be getting for the b-e/b-c diode checks? How do the MOSFETs differ from the others and do I need to test them differently? It's amazing how clean and efficient soldering can be if done correctly! It also helps to have the right tools .
Question about the remaining amp modules. For the three good ones that remain, will I have to adjust the PSU to account for the lack of the two modules? I guess the different modules are in parallel with each other, meaning same constant voltage, but will they draw more current now that two are missing? If so, how will this affect them?
Note to MTA: Sorry about the lack of support for your specific case. I'm sure that whatever we learn from this escapade can be applied to your situation. If I ever do get this working, I'll be sure to report fully on how it's done. Wish me luck
It's funny, because I'm sure that someone who knows what they are doing would have this done in a few minutes! I guess this is just part of my learning experience...
.Question about the remaining amp modules. For the three good ones that remain, will I have to adjust the PSU to account for the lack of the two modules? I guess the different modules are in parallel with each other, meaning same constant voltage, but will they draw more current now that two are missing? If so, how will this affect them?
Note to MTA: Sorry about the lack of support for your specific case. I'm sure that whatever we learn from this escapade can be applied to your situation. If I ever do get this working, I'll be sure to report fully on how it's done. Wish me luck
It's funny, because I'm sure that someone who knows what they are doing would have this done in a few minutes! I guess this is just part of my learning experience...
I'm being patient since this is a learning experience for everyone. I realize that whatever steps you forge I'll be able to duplicate. Let me know how I can help.
As an aside, I recently picked up a AVR-202 on Ebay for less than $100, including shipping advertised as "not working." I opening it to find that one of the boards on top was not in its slot. I didn't yet test the the receiver but I'm crossing my fingers that that was all that was wrong with it.
As an aside, I recently picked up a AVR-202 on Ebay for less than $100, including shipping advertised as "not working." I opening it to find that one of the boards on top was not in its slot. I didn't yet test the the receiver but I'm crossing my fingers that that was all that was wrong with it.
Depending on what happens to my current heap... Would you be at all interested in selling that 202 to me? I have a feeling that the amp modules would exactly match the ones in the 202i and so I could replace the blown ones easily. Completely your call, of course, but I'll probably be looking for one regardless. At the moment I don't have any amps (or preamps) to use with my speakers (*sigh*).
You'll need to pull the output transistors and the driver transistors (Q1, Q8) off the PCB and check for b-e and b-c diode function.
I'd check Q4 & Q5 as well but then I'm paranoid
I pulled one of the MOSFET output trannies and both Q1 and Q8.
I tested Q1 and Q8 to find that Q8 failed open circuit. Q1 seems to be OK.
I haven't yet pulled Q4 or Q5, but I'm planning to do so shortly.
I'm having trouble testing the MOSFET o/p trannies. I've been looking for a reliable procedure on the internet, but all of the ones that I've found are inconsistent and not very helpful. Can you suggest anything?
so the trannies measure between 0.5V and 0.7V on the diode scale in one direction and open circuit in the other. For each transistor you can hold the base with one probe and check e & c are the same. One polarity conducts for pnp, the other conducts for npn.
I'm not a FET guy so the following is probably heavy handed.
I'd build a circuit with clip leads and leaded components to connect the FET source to gnd and FET drain to +ve supply through a power resistor. 12V through a 100ohm resistor will draw 120mA for 1.5W dissipation in the resistor.
Use a pot to vary the gate voltage (make sure you start at 0V measure before applying, excessive volts can destroy the FET) up until the drain voltage falls to 0V. You can then check Vg(th) and Rds(on).
That's for QP1-3 (2SJ162), QN1-3 (2SK1058) is reverse polarity. There's probably a better way, anyone?
I'm not a FET guy so the following is probably heavy handed.
I'd build a circuit with clip leads and leaded components to connect the FET source to gnd and FET drain to +ve supply through a power resistor. 12V through a 100ohm resistor will draw 120mA for 1.5W dissipation in the resistor.
Use a pot to vary the gate voltage (make sure you start at 0V measure before applying, excessive volts can destroy the FET) up until the drain voltage falls to 0V. You can then check Vg(th) and Rds(on).
That's for QP1-3 (2SJ162), QN1-3 (2SK1058) is reverse polarity. There's probably a better way, anyone?
Back to start (almost)
Ok,
MTAtech was nice enough to sell me the two module amp board from the "as-is" avr-202 he got recently online. He reports that the heatsinks do get warm, meaning there's a quiescent current, correct? If the board is fully functional, I'm basically where I was a couple of weeks ago, with working power amp sections and PSU. Now, what steps should I take from here to ensure that I don't damage these boards as well? Should I continue with the failure analysis of the original 2 module amp board? I'm going to go a bit more cautiously and I'd like to some ideas on where to go. Thanks again, in advance.
Ok,
MTAtech was nice enough to sell me the two module amp board from the "as-is" avr-202 he got recently online. He reports that the heatsinks do get warm, meaning there's a quiescent current, correct? If the board is fully functional, I'm basically where I was a couple of weeks ago, with working power amp sections and PSU. Now, what steps should I take from here to ensure that I don't damage these boards as well? Should I continue with the failure analysis of the original 2 module amp board? I'm going to go a bit more cautiously and I'd like to some ideas on where to go. Thanks again, in advance
.
make a sketch of the connections you need to make and double check your set up against it. Drawing it out will force errors to light.
Swap the fuses for 0.75A slow-blo. If the amp can't power up on that then somethings wrong.
Use an 8ohm, >1W resistor as speaker load.
Tie enable low, connect your voltmeter across the load resistor and watch as you power up. If it doesn't quickly center to 0V (±1V) quickly disconnect the power - there's a problem.
Due to the feedback loop of the amp there's no way of powering up sections one at a time. You just have to jump in but this should minimize the risk from a set-up error.
Good luck
Swap the fuses for 0.75A slow-blo. If the amp can't power up on that then somethings wrong.
Use an 8ohm, >1W resistor as speaker load.
Tie enable low, connect your voltmeter across the load resistor and watch as you power up. If it doesn't quickly center to 0V (±1V) quickly disconnect the power - there's a problem.
Due to the feedback loop of the amp there's no way of powering up sections one at a time. You just have to jump in but this should minimize the risk from a set-up error.
Good luck
Amps arrived.
The 2 module amp board arrived today (Thanks MTA). I've got a band practice in an hour, so I can't do much tonight. I plugged the new 2 module board in with the 3 module board (nothing modified, CTRL not grounded, no inputs, ect) just to see if things appeared functional at first glance. I get a steady 0.02 V across all five of the speaker terminals, so I take that as a promising sign (since the last two module board showed 40V at speaker out ). I'm also going to order some supplies that Iain mentioned before I dive in again, so it may be a few days (I'll be away this weekend as well ) before I can truly get working on this again.
What types of potentiometers do you recommend for the level controls? Do I just connect those in series after the RCA jacks for inputs?
I'll sketch something up in the following days and scan it in to double check with you on the connections.
Wow, I can't wait to get this thing working! Hope all goes well... A friend of mine let me borrow his old receiver for the time being. It's a SONY, and frankly, I doesn't hold a candle to what I remember of the B&K. Oh well.
I'll report back soon, Cheers!
The 2 module amp board arrived today (Thanks MTA
). I've got a band practice in an hour, so I can't do much tonight. I plugged the new 2 module board in with the 3 module board (nothing modified, CTRL not grounded, no inputs, ect) just to see if things appeared functional at first glance. I get a steady 0.02 V across all five of the speaker terminals, so I take that as a promising sign (since the last two module board showed 40V at speaker out ). I'm also going to order some supplies that Iain mentioned before I dive in again, so it may be a few days (I'll be away this weekend as well ) before I can truly get working on this again.What types of potentiometers do you recommend for the level controls? Do I just connect those in series after the RCA jacks for inputs?
I'll sketch something up in the following days and scan it in to double check with you on the connections.
Wow, I can't wait to get this thing working! Hope all goes well... A friend of mine let me borrow his old receiver for the time being. It's a SONY, and frankly, I doesn't hold a candle to what I remember of the B&K. Oh well.
I'll report back soon, Cheers!
Glad the 2-amp board arrived on time. What you said about what you remember about the sound of the B&K is how I feel too. I bought a B&K AVR-202 in 2000, and the moment that I powered it up I was impressed with the sound. I replaced it with a B&K AVR-307 in 2007, and it was a bit punchier than the 202.
I'm currently using a Denon 3808ci, because it has all the modern inputs and codecs, but the Denon amp section sucks -- it's not even recommended for 4 ohm speakers. So, I am using the Denon as a pre-amp to an Emotiva 7-channel amp. The Emotiva 7-channel amp can't hold a candle to the B&K (that's why I want to turn the 307 into a power amp.)
I'm currently using a Denon 3808ci, because it has all the modern inputs and codecs, but the Denon amp section sucks -- it's not even recommended for 4 ohm speakers. So, I am using the Denon as a pre-amp to an Emotiva 7-channel amp. The Emotiva 7-channel amp can't hold a candle to the B&K (that's why I want to turn the 307 into a power amp.)
OOO Emotiva! I've heard alot about them lately and been wondering how they compared. You say that the B&K is much better? How many watts/ch is the Emotiva? How does it stack up to other ones you've heard?
Edit: sorry, I'm going off topic a bit, but I think that there are only a few people (I count three) even interested in this thread.
Edit: sorry, I'm going off topic a bit, but I think that there are only a few people (I count three) even interested in this thread.
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