DIY Transistor Amp Using NVA Boards
- Dave the bass
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#91 Re: DIY Transistor Amp Using NVA Boards
Ooo errr.
Where did the smoke come from Steve? If it was me I'd check TX phase and rectifiers.
Where did the smoke come from Steve? If it was me I'd check TX phase and rectifiers.
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- pre65
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#92 Re: DIY Transistor Amp Using NVA Boards
Many years ago I had transformer smoke and TX phase was the problem.
The only thing necessary for the triumph of evil is for good men to do nothing.
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Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
#93 Re: DIY Transistor Amp Using NVA Boards
Where from?then smoke wisps
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#94 Re: DIY Transistor Amp Using NVA Boards
If the caps are metal cased, make sure they are isolated from the chassis as the -ve terminal will be connected to the can of the transformer (this has caught me out before).
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
- Cressy Snr
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#95 Re: DIY Transistor Amp Using NVA Boards
Thanks for the suggestions guys. The smoke came from the on off switch, just a small wisp. That was enough to trigger a hurried switch-off. I’ll have a look tomorrow.
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- pre65
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#96 Re: DIY Transistor Amp Using NVA Boards
I've wired up DP on/off switches incorrectly in the past.Cressy Snr wrote: ↑Sat Jan 18, 2020 11:49 pm Thanks for the suggestions guys. The smoke came from the on off switch, just a small wisp. That was enough to trigger a hurried switch-off. I’ll have a look tomorrow.
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
#97 Re: DIY Transistor Amp Using NVA Boards
I'm sure will soon get the issue sorted Steve
You would think relatively simple solid state would be easy after valve amps.. but my first chip amp is going pretty crap... a simple tda 2030, but it just loves to ossilate.. after a month I still can't plug anything into it ! Although it seems ok untill I wave the phono cable anywhere near it
Best of luck..
You would think relatively simple solid state would be easy after valve amps.. but my first chip amp is going pretty crap... a simple tda 2030, but it just loves to ossilate.. after a month I still can't plug anything into it ! Although it seems ok untill I wave the phono cable anywhere near it
Best of luck..
Last edited by steve s on Sun Jan 19, 2020 1:00 pm, edited 1 time in total.
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#98 Re: DIY Transistor Amp Using NVA Boards
Yes, SS at the moment, is a royal PITA . When Richard sent me the boards, he told me, in his email, that he wanted to see a valve bloke, try and do a transistor amp, and that he knew he would be p*ssing himself laughing at my attempts to get his boards going.steve s wrote: ↑Sun Jan 19, 2020 12:17 pm I'm sure will soon get the issue sorted Steve
You would think relatively simple solid state would be easy after valve amps.. but my first chip amp is going pretty crap... a simple tda 2030, but it just loves to ossilate.. after a month I still can't plug anything into it ! Although it seems ok untill I wave the phone cable anywhere near it
Best of luck..
He’s definitely up there laughing at the moment.
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#99 Re: DIY Transistor Amp Using 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. Sod’s Law of course ensured that said cap just happened to have its negative terminal as the power feed, with its positive as 0V.
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, plus I threw away the offending cap clamp, and everything fires up properly without incident.
Now we can put in the wires to the boards etc.
Last edited by Cressy Snr on Sun Jan 19, 2020 4:00 pm, edited 1 time in total.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
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#100 Re: DIY Transistor Amp Using NVA Boards
Well done on finding the problem Steve.
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- pre65
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#101 Re: DIY Transistor Amp Using NVA Boards
Yes, well done Steve.
I prefer to use non metallic capacitor clamps if possible.
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
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- Cressy Snr
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#102 Re: DIY Transistor Amp Using NVA Boards
Thanks chaps.
It’s non metallic clamps for me from now on.
Power supply all done; double pole switching (with fuse in the live side of course)
Chassis divider repositioned to serve as a heat shield between caps and heat sinks.
It’s non metallic clamps for me from now on.
Power supply all done; double pole switching (with fuse in the live side of course)
Chassis divider repositioned to serve as a heat shield between caps and heat sinks.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
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#103 Re: DIY Transistor Amp Using NVA Boards
Cressy Snr wrote: ↑Sun Jan 19, 2020 3:08 pmHere was the problem:
Image
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.
Anyhow, that's alright then!
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
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#104 Re: DIY Transistor Amp Using NVA Boards
The story so far:
KERBLAMMM!, then ...cough..splutter..then...”darling, where’s the dustpan and brush? ...No....don’t come in the kitchen just yet!”....”I know there’s a draught; I’ve got the back door open!” then.... “feck it I’ll stick with valves”
Just the power rails and the input socket wiring to install, then it’ll be switch-on, shortly followed by...Sgt. Baker started talkin’ with a Bullhorn in his hand.
- Cressy Snr
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#105 Re: DIY Transistor Amp Using NVA Boards
Board wiring and inputs all done:
Sgt. Baker started talkin’ with a Bullhorn in his hand.