Another DIY SS Amplifier with NVA Boards
- SteveTheShadow
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Re: Another DIY SS Amplifier with NVA Boards
I’ve ended the day utterly pissed off!
Two power supplies all wired in. Fire up to check it functions and the large transformer goes beserk, drawing massive current, yet voltages on its associated caps check out fine, then smoke wisps, so switch off. Small psu is fine. The large transformer is also fine; until it is in circuit.
Can’t find any shorts, but something is causing the large current draw. All I can think of is either a duff cap or bridge rectifier; there’s nothing else, unless I’ve somehow created a shorted turn with the fixing bolt. Either way the fault has got to be found or I’m going to have to abandon the dual power supply idea.
Is there some kind of black art with multiple bipolar PSUs that I’m not in on?
Two power supplies all wired in. Fire up to check it functions and the large transformer goes beserk, drawing massive current, yet voltages on its associated caps check out fine, then smoke wisps, so switch off. Small psu is fine. The large transformer is also fine; until it is in circuit.
Can’t find any shorts, but something is causing the large current draw. All I can think of is either a duff cap or bridge rectifier; there’s nothing else, unless I’ve somehow created a shorted turn with the fixing bolt. Either way the fault has got to be found or I’m going to have to abandon the dual power supply idea.
Is there some kind of black art with multiple bipolar PSUs that I’m not in on?
Somebody’s telling me the latest scandals.
Somebody’s stepping on my plastic sandals. Joe Jackson (1979)
Somebody’s stepping on my plastic sandals. Joe Jackson (1979)
- karatestu
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Re: Another DIY SS Amplifier with NVA Boards
Nope, not that i know of. Only the 0V arrangement caused any chin scratching.SteveTheShadow wrote: ↑Sat Jan 18, 2020 7:29 pm
Is there some kind of black art with multiple bipolar PSUs that I’m not in on?
I would be trying different rectifiers and caps to rule them out.
Hope you get it sorted.
DIY FREE ZONE
- SteveTheShadow
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Re: Another DIY SS Amplifier with NVA Boards
Thanks Stu,
I’ll have a look in the morning.
I’ll have a look in the morning.
Somebody’s telling me the latest scandals.
Somebody’s stepping on my plastic sandals. Joe Jackson (1979)
Somebody’s stepping on my plastic sandals. Joe Jackson (1979)
- SteveTheShadow
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Re: Another DIY SS Amplifier with NVA Boards
Here was the problem:
Sharp edge on the inside of one of the cap clamps on the larger power supply, had cut through the plastic insulation, and caused a high resistance ground fault to the earthed chassis, via the can of the offending cap. This must have been enough of a short, to pull excessive current through the large transformer. Anyway I’ve replaced the whole rectifier/transformer/capacitor network and everything fires up properly without incident.
I also binned the offending cap clamp.
Now we can put in the wires to the boards etc.
Sharp edge on the inside of one of the cap clamps on the larger power supply, had cut through the plastic insulation, and caused a high resistance ground fault to the earthed chassis, via the can of the offending cap. This must have been enough of a short, to pull excessive current through the large transformer. Anyway I’ve replaced the whole rectifier/transformer/capacitor network and everything fires up properly without incident.
I also binned the offending cap clamp.
Now we can put in the wires to the boards etc.
Somebody’s telling me the latest scandals.
Somebody’s stepping on my plastic sandals. Joe Jackson (1979)
Somebody’s stepping on my plastic sandals. Joe Jackson (1979)
- SteveTheShadow
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Re: Another DIY SS Amplifier with NVA Boards
Power supply all done; double pole switching (with fuse in the live side of course)
Chassis divider repositioned as a heat shield between caps and heat sinks.
Chassis divider repositioned as a heat shield between caps and heat sinks.
Somebody’s telling me the latest scandals.
Somebody’s stepping on my plastic sandals. Joe Jackson (1979)
Somebody’s stepping on my plastic sandals. Joe Jackson (1979)
- Latteman
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Re: Another DIY SS Amplifier with NVA Boards
Such a simple fault- was it easy to spot.
When’s the switch on?
When’s the switch on?
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GL-59; ARB uni pivot; AT- Signet mc
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Doug Self balanced Pre amp
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Denon DP47f; AT-VM95SH- RigB 9
GL-59; ARB uni pivot; AT- Signet mc
Nva phono mm/mc
Doug Self balanced Pre amp
Akai 4000DS mk2 R2R
Digital Sources- Argon Pi4 v2; IfI iUSB 3.0, Ifi Neo idsd Dac;
Tidal / Radio Paradise
Amplification Nva 300va mono blocks
Speakers Lii Audio F-15 in Open Baffle; Ls6
Weiduka AC8.8- for digital sources
Mini BMU for analog sources
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Re: Another DIY SS Amplifier with NVA Boards
Obviously very annoying. Good luck with the rest of the build.SteveTheShadow wrote: ↑Sun Jan 19, 2020 4:11 pm
Sharp edge on the inside of one of the cap clamps on the larger power supply, had cut through the plastic insulation, and caused a high resistance ground fault to the earthed chassis, via the can of the offending cap. This must have been enough of a short, to pull excessive current through the large transformer. Anyway I’ve replaced the whole rectifier/transformer/capacitor network and everything fires up properly without incident.
I also binned the offending cap clamp.
Now we can put in the wires to the boards etc.
I use acrylic cases and glue in caps with Bison kit so avoiding issues like that.
Alfi.
I am in the hi-fi trade.
Status: Manufacturer.
Company Name: Analogue innovation.
Contact: a_innovation@btinternet.com
- SteveTheShadow
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Re: Another DIY SS Amplifier with NVA Boards
No it fecking well wasn’t!
Richard must be up there p*ssing himself laughing
Somebody’s telling me the latest scandals.
Somebody’s stepping on my plastic sandals. Joe Jackson (1979)
Somebody’s stepping on my plastic sandals. Joe Jackson (1979)
- SteveTheShadow
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Re: Another DIY SS Amplifier with NVA Boards
The story so far:
Then it’ll be, throw the switch, shortly followed by..... KERBLAMM!.... then,
“Darling..where’s the dustpan and brush?...er...don’t come in the kitchen just yet.
Just the power rails and the input sockets to do tomorrow.Then it’ll be, throw the switch, shortly followed by..... KERBLAMM!.... then,
“Darling..where’s the dustpan and brush?...er...don’t come in the kitchen just yet.
Somebody’s telling me the latest scandals.
Somebody’s stepping on my plastic sandals. Joe Jackson (1979)
Somebody’s stepping on my plastic sandals. Joe Jackson (1979)
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Re: Another DIY SS Amplifier with NVA Boards
Hats off to you Steve, that looks to be a fine and time consuming project. I hope it sounds sweet when it's finally connected
Modified Airlink BPS 3110S with LDA DC filter
TTs, Kenwood KD 8030 with AT OC9XSH, Opera Consonance Wax Engine mk2 with modified Apheta 2 MC cart, PT TOO awaiting restoration.
LDA MCJ3 phono,Schiit Freya plus pre amp, NAD M23, Audiolab 9000 CD transport, Denafrips Pontus 2 DAC, Mano Ultra2 streamer, Cisco switch, Audio Technica ATH 70 cans, Serhan Swift Mu2 mk2 speakers & NSNO W48.5 speaker cables
TTs, Kenwood KD 8030 with AT OC9XSH, Opera Consonance Wax Engine mk2 with modified Apheta 2 MC cart, PT TOO awaiting restoration.
LDA MCJ3 phono,Schiit Freya plus pre amp, NAD M23, Audiolab 9000 CD transport, Denafrips Pontus 2 DAC, Mano Ultra2 streamer, Cisco switch, Audio Technica ATH 70 cans, Serhan Swift Mu2 mk2 speakers & NSNO W48.5 speaker cables