B&W PV1 Subwoofer - Guide for repair - help

salzy

Active Member
Hi

I found the fault with the PV1 i am repairing
It turned out to be the 470uF 16V capacitor (labeled C824), the ESR of this cap was over 20 ohms! (it was meant to be less than 1 ohm when new)

Why did it fail? probably because they used low temp, short life span SMG branded caps (85 degreesC at 2,000 hours) and it is close to other components that get quite hot, there is even a slight bit of heat caused discoloration on the small 2.2 ohm resistor (labeled R818)

I also tested the ESR of all the other SMG caps and they are also have higher ESR values above what they should be when new, but probably not out of spec enough to cause problems (yet)

The big brown nippon caps all measured low ESRs and are 105 degrees C rated

If you intend to measure the ESRs of the caps dont forget to discharge them via a resistor beforehand

I replaced the faulty cap with a higher operating temp longer life cap

Here is a link to an informative site about capacitors

If this cap replacement does not work for you, then check for dry solder joints, and also if needed, get a component tester (ie, Multi function Tester TC1 ) to test other components like semiconductors etc

+1 for the hair dryer tip,

cheers, and good luck

AND REMEMBER BE CAREFUL OF THE HIGH VOLTAGES THAT ARE PRESENT ON THIS EQUIPMENT!!

Read the safety first comment on this following link before working on the SMPS power board of the PV1
Troubleshooting switch mode power supplies
glad to see this thread has some promising news. which board is c824 cap located on?
 

F3rrograph

Member
I repaired one of these a few years back and the resistor R818 (2.2R) was open circuit and thus the sub would not wake up. I replaced the resistor and its has been working for 4yr without issue.

It recently developed a new fault though with a earth type buzz without anything connected - so looks like I need to open it up again and change some caps.

The hair dryer tip to open the two halves was a good one, but I used the long bolts to force it open by putting the nuts on the inside and slowly turning them to exert force pushing the two halves apart. Think I'll try the hair dryer this time!

1609782913476.png
 

salzy

Active Member
IMG_20201226_214011.jpg

Main board if anyone's Interested. Found the main cap here way over the ESR but because caps generally don't have a long time span and B&W have used some cheapo ones I ended up just changing all of them
 

F3rrograph

Member
Main board if anyone's Interested. Found the main cap here way over the ESR but because caps generally don't have a long time span and B&W have used some cheapo ones I ended up just changing all of them

When you say the main cap do you mean the big brown mains rectifier cap 470uF 420v?
 

salzy

Active Member
When you say the main cap do you mean the big brown mains rectifier cap 470uF 420v?
No I left all the big brown ones as there were still well within tolerance and they're pretty pricey to replace
C823. As circled below
IMG_20210104_190505.jpg
 

F3rrograph

Member
No I left all the big brown ones as there were still well within tolerance and they're pretty pricey to replace
C823. As circled below

Ah right, yes right next to R818 which as you noted gets hot (underrated perhaps). I replaced with a bigger watt rating.

Thanks that's really helpful.
 

salzy

Active Member
Ah right, yes right next to R818 which as you noted gets hot (underrated perhaps). I replaced with a bigger watt rating.

Thanks that's really helpful.
No worries. Yeah just go for the next voltage up on all of them. No harm as long as you keep the Uf value the same. The Panasonic FC or FM class are a good choice for replacement caps. They have low ESR and are meant to be pretty good for AV equipment
 

1William

Member
I repaired one of these a few years back and the resistor R818 (2.2R) was open circuit and thus the sub would not wake up. I replaced the resistor and its has been working for 4yr without issue.

It recently developed a new fault though with a earth type buzz without anything connected - so looks like I need to open it up again and change some caps.

The hair dryer tip to open the two halves was a good one, but I used the long bolts to force it open by putting the nuts on the inside and slowly turning them to exert force pushing the two halves apart. Think I'll try the hair dryer this time!

View attachment 1435137
I sort of have the same issue. I can get a green light. No audio though. If I power it down, wait, touch the RCA jack tip, power up, I can get HUM for about one second then I believe I can hear a single click of a relay then silence.
I am a bit old and poor sighted. However, I was able to take it all apart in a methodical and slow (four hours!!!) manner. The PV is sure built like a tank and well engineered. However the electronics are no where as impressive.
I got the power supply out and with reading glasses and a magnifier, I looked it over. No bulging caps. I put a meter on R818 and got about 3K, so not open. I was so hoping the resistor was the fault, I even have a few 1/4 watt ones I think from Radio Shack some place here. Wouldn't that of been nice. No signs of running hot. The soldering job was not impressive however, I am not up to the task of re-flowing it. I'd just make a bad problem worse (if that is possible).
I have contacted B&W in MA, they will not service it due to the age. Great. I spoke to a few repair places on the East Coast and while all good guys and they tried to be helpful, none were interested in repair. Most were completely unfamiliar with it.

I want to thank every who has participated in this thread for the guidance they provided enabling me to take it apart without damage and perhaps find the fault easily. Glue N Gaskets! I was nervous putting it back together but everything pretty much fell back into place intuitively. I tested it and it is the same, dead. No 'spare parts' either!

So now I have a 45 pound boat anchor that cost a lot of money. If anyone thinks they can help me, please feel free to PM me. In a perfect world, I'd pull the drivers (why ship 30 pounds of magnets) and mail the vessel to a better person than I for repair.
 

salzy

Active Member
I sort of have the same issue. I can get a green light. No audio though. If I power it down, wait, touch the RCA jack tip, power up, I can get HUM for about one second then I believe I can hear a single click of a relay then silence.
I am a bit old and poor sighted. However, I was able to take it all apart in a methodical and slow (four hours!!!) manner. The PV is sure built like a tank and well engineered. However the electronics are no where as impressive.
I got the power supply out and with reading glasses and a magnifier, I looked it over. No bulging caps. I put a meter on R818 and got about 3K, so not open. I was so hoping the resistor was the fault, I even have a few 1/4 watt ones I think from Radio Shack some place here. Wouldn't that of been nice. No signs of running hot. The soldering job was not impressive however, I am not up to the task of re-flowing it. I'd just make a bad problem worse (if that is possible).
I have contacted B&W in MA, they will not service it due to the age. Great. I spoke to a few repair places on the East Coast and while all good guys and they tried to be helpful, none were interested in repair. Most were completely unfamiliar with it.

I want to thank every who has participated in this thread for the guidance they provided enabling me to take it apart without damage and perhaps find the fault easily. Glue N Gaskets! I was nervous putting it back together but everything pretty much fell back into place intuitively. I tested it and it is the same, dead. No 'spare parts' either!

So now I have a 45 pound boat anchor that cost a lot of money. If anyone thinks they can help me, please feel free to PM me. In a perfect world, I'd pull the drivers (why ship 30 pounds of magnets) and mail the vessel to a better person than I for repair.
I assume you got access to the 3rd board if you opened it. If you have a ESR meter test the caps and if you find one that's high that's prob the culprit.
Mine started with the clicking so first 8 changed the caps on the ice amp board. Then I had the problem you mention, lights up but nobody home. But once I replaced all the caps on the 3rd board ( only one was a dud) she came back to life
 

1William

Member
I assume you got access to the 3rd board if you opened it. If you have a ESR meter test the caps and if you find one that's high that's prob the culprit.
Mine started with the clicking so first 8 changed the caps on the ice amp board. Then I had the problem you mention, lights up but nobody home. But once I replaced all the caps on the 3rd board ( only one was a dud) she came back to life
Yes, I did have it nearly 100% apart. My inspection was focused on the power supply board. No ESR meter plus my eyesight is so poor, removing caps and replacing is not something I can do anymore.
My original guess was a cap. I do get a green light. I never noticed any clicking . I assume the clicking people are talking about is pops through the drivers and not the subtle sounds of relays
 

KEREGR

Novice Member
I sort of have the same issue. I can get a green light. No audio though. If I power it down, wait, touch the RCA jack tip, power up, I can get HUM for about one second then I believe I can hear a single click of a relay then silence.
I am a bit old and poor sighted. However, I was able to take it all apart in a methodical and slow (four hours!!!) manner. The PV is sure built like a tank and well engineered. However the electronics are no where as impressive.
I got the power supply out and with reading glasses and a magnifier, I looked it over. No bulging caps. I put a meter on R818 and got about 3K, so not open. I was so hoping the resistor was the fault, I even have a few 1/4 watt ones I think from Radio Shack some place here. Wouldn't that of been nice. No signs of running hot. The soldering job was not impressive however, I am not up to the task of re-flowing it. I'd just make a bad problem worse (if that is possible).
I have contacted B&W in MA, they will not service it due to the age. Great. I spoke to a few repair places on the East Coast and while all good guys and they tried to be helpful, none were interested in repair. Most were completely unfamiliar with it.

I want to thank every who has participated in this thread for the guidance they provided enabling me to take it apart without damage and perhaps find the fault easily. Glue N Gaskets! I was nervous putting it back together but everything pretty much fell back into place intuitively. I tested it and it is the same, dead. No 'spare parts' either!

So now I have a 45 pound boat anchor that cost a lot of money. If anyone thinks they can help me, please feel free to PM me. In a perfect world, I'd pull the drivers (why ship 30 pounds of magnets) and mail the vessel to a better person than I for repair.
 

KEREGR

Novice Member
Hello, I buy B&W PV1 for spare parts. If anyone only has a motherboard I will be happy. thank you all for the offers.
 

Conrad.

Moderator
Hello, I buy B&W PV1 for spare parts. If anyone only has a motherboard I will be happy. thank you all for the offers.

Probably best if you put a wanted ad in the Classifieds section. You can link to it from here though.
 

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