Hello,
Wonder if any of you have seen this. I am being cautious but here is one of the issues (there are a few others).
The schematic shows two filter caps at 3300uf on my 1b BUT in the actual preamp I find two 1500uf caps. bryston.com/PDF/Manuals/1B_MANUAL.pdf
So, my question is, does Bryston make changes like this in production or do you all think it's a bad fix from a previous owner?
More important should I use the 1500uf caps or put in the 3300uf to be accurate to the manual?
thoughts?
Thanks,
brian
Wonder if any of you have seen this. I am being cautious but here is one of the issues (there are a few others).
The schematic shows two filter caps at 3300uf on my 1b BUT in the actual preamp I find two 1500uf caps. bryston.com/PDF/Manuals/1B_MANUAL.pdf
So, my question is, does Bryston make changes like this in production or do you all think it's a bad fix from a previous owner?
More important should I use the 1500uf caps or put in the 3300uf to be accurate to the manual?
thoughts?
Thanks,
brian
The other issue with this unit was some bad soldering on the riser boards that I hope was causing my main issue with the left channel. While in the unit I am replacing the electrolytic's so hopefully I don't have to touch this again for another couple decades
I am using a combination of Elna and Nichicon as they are what I could get currently between mouser and digikey.
Sorry for the image quality on this one folks. the cap is 1500uf 63v and seems to be the same as other threads show in dyiaudio
Here is an image of the caps:
Here is the whole inside:
I am using a combination of Elna and Nichicon as they are what I could get currently between mouser and digikey.
Sorry for the image quality on this one folks. the cap is 1500uf 63v and seems to be the same as other threads show in dyiaudio
Here is an image of the caps:
Here is the whole inside:
Last edited:
Are you certain no one has already beaten you to re-capping it? It does seem unlikely that a manufacturer would see a reason to downsize the smoothing caps, even though they are still likely plenty big enough for a preamplifier. Perhaps height was an issue for the available types for recapping, too.
In my experience, big caps here can cause excessive thumps when powering up/down if muting circuits are either bypassed, faulty or not fully effective. Smaller caps may help with that, as would deliberately mismatched values. I've had to do that myself but this goes beyond routine maintenance. If they fit, the schematic values (check the appropriate drawing revision/issue and bill of materials) should be right every time.
Using upgraded quality and performance parts is really another matter as ongoing development of components leaves old products behind. Whether or not its an option, will be down to your estimation of what it should sound and perform like. Part of the fun of DIY, I'd say
.
In my experience, big caps here can cause excessive thumps when powering up/down if muting circuits are either bypassed, faulty or not fully effective. Smaller caps may help with that, as would deliberately mismatched values. I've had to do that myself but this goes beyond routine maintenance. If they fit, the schematic values (check the appropriate drawing revision/issue and bill of materials) should be right every time.
Using upgraded quality and performance parts is really another matter as ongoing development of components leaves old products behind. Whether or not its an option, will be down to your estimation of what it should sound and perform like. Part of the fun of DIY, I'd say
.
Thank you Ian, that's what I was suspecting. I appreciate your reply. If I get a big inrush or funny things at power on what I might do is push those caps back to the prior size of 1500uf.
I was able to get the 3300uf caps in there, will post pics soon. I had to move a few components to get them to fit but it worked out ok I think. Will know when I put power back to it and dial the voltage up!
I was able to get the 3300uf caps in there, will post pics soon. I had to move a few components to get them to fit but it worked out ok I think. Will know when I put power back to it and dial the voltage up!
more images of the fix in progress
Hello,
Thought I would share these as I get this thing working again.
here is the joint that was actually physically not connected, the board was just sitting on it. I hope and think this was my primary issue. see the bottom hole in the board, it should have the piece of bare wire like the two above it
Here is a close up of the smoothing cap that is the wrong uf but seems the right vintage and type:
Here are the 3300 uf caps I just installed. Note they did not fit like the older ones so they look like they are in backwards but thats because the way the traces run on the board:
More to come.
Hello,
Thought I would share these as I get this thing working again.
here is the joint that was actually physically not connected, the board was just sitting on it. I hope and think this was my primary issue. see the bottom hole in the board, it should have the piece of bare wire like the two above it
Here is a close up of the smoothing cap that is the wrong uf but seems the right vintage and type:
Here are the 3300 uf caps I just installed. Note they did not fit like the older ones so they look like they are in backwards but thats because the way the traces run on the board:
http://brianhiatt.smugmug.com/Hobbies/Electronics/Bryston-1b/i-XnwBnbg/0/M/IMG_0062-M.jpg][/INDENT]
Second view:
[INDENT][IMG]https://brianhiatt.smugmug.com/Hobbies/Electronics/Bryston-1b/i-bhrk5B7/0/M/IMG_0061-M.jpg
Second view:
[INDENT][IMG]https://brianhiatt.smugmug.com/Hobbies/Electronics/Bryston-1b/i-bhrk5B7/0/M/IMG_0061-M.jpg
More to come.
Last edited:
Some more pics
Here is the moved items to fit the new filter caps.
Two items are moved to the bottom of the board: 1. two resistors for the power led. 2. the mda200 3n25e Diode Rectifier Bridge (sorry have not cleaned the flux yet so it's a bit hard to see the joints but they seem sound.
In this image you can see the new joints for the filter caps, the bridge and the two resistors.
Here is the moved items to fit the new filter caps.
Two items are moved to the bottom of the board: 1. two resistors for the power led. 2. the mda200 3n25e Diode Rectifier Bridge (sorry have not cleaned the flux yet so it's a bit hard to see the joints but they seem sound.
In this image you can see the new joints for the filter caps, the bridge and the two resistors.
Greetings Brian,
I hope you don't mind me resurrecting this thread - the title still seems suitable.
I have a 1B with considerable 60Hz noise on both phono inputs - even when disconnected from the turntable / phono ground.
Line-level inputs, by comparison, seem very quiet and clean.
Did you notice a reduction in noise (especially ground noise) when you replaced the big filter caps?
Regards, Mike
I hope you don't mind me resurrecting this thread - the title still seems suitable.
I have a 1B with considerable 60Hz noise on both phono inputs - even when disconnected from the turntable / phono ground.
Line-level inputs, by comparison, seem very quiet and clean.
Did you notice a reduction in noise (especially ground noise) when you replaced the big filter caps?
Regards, Mike
Those 1500s look like the factory originals to me. Perhaps the 3300 in the manual was a typo? I've only seen like a million errors in these older manuals ":^)
As for hum, note the RCAs are soldered directly to the board & are vertical. Heavy audiophile cables the size of an air hose are really rough on these. Check for cracked solder joints on all of them.
As for hum, note the RCAs are soldered directly to the board & are vertical. Heavy audiophile cables the size of an air hose are really rough on these. Check for cracked solder joints on all of them.
Hah! That's good thinking. I've never personally spent thousands on 10 gauge, active-vacuum, nitrogen-cooled cryogenic silver RCA patches, but your point still applies. An almost 40 year-old preamp may well be showing mechanical stress faults. I already replaced the power cord for that exact reason (almost 20 years ago already!).
I'm going to try one last thing before taking it off the rack and opening it up: taking it off the OneAC power conditioner - to see whether the ~55dB of power noise changes at all. I call it 'power' because I can't prove that it has anything to do with grounding. Power filtering deterioration could be a possibility. Although I have other gear from the '80s - I haven't yet seen the kind of deterioration of capacitors that some folks complain of. And the internals of the Bryston gear of that period look more like avionics than audio!
Oh, and just by the by - the pictures above are from Brian's unit. When I get around to opening up my 1B I'll post a few pictures for comparison.