DIY amp build: Done with the headshell ..now comes the tough part :p

[Phantasmagoria]

Re: DIY amp build: Done with the headshell ..now comes the tough part

Quietly, I suddenly realized there was a channel missing. I've tested it, it still outputs voltage but it's down at the outputs and the 12 v out doesn't seem to work at all which is weird because there was nothing connected to it. It won't run anything. No signs of damage. There's a mounted fuse on them , near the power [AC] connections. I checked it - all good.

If the 12V supply does'nt work then I guess something's wrong at the input? The fuse would've been the most obvious culprit... yeah it's pretty strange. Is the fuse one of those SMD things? My PS board that popped & died shows no sign of damage anywhere except for one little SMD component that seems to be missing (blown off?). I think it may have been the fuse.

Funny, when I ran a continuity test on the amp board that died after I unscrewed/re-screwed the fan, there was no break in the circuit..so it's probably an IC that went out..

 

[GoldenVulture]

Re: DIY amp build: Done with the headshell ..now comes the tough part

If the 12V supply does'nt work then I guess something's wrong at the input? The fuse would've been the most obvious culprit... yeah it's pretty strange. Is the fuse one of those SMD things? My PS board that popped & died shows no sign of damage anywhere except for one little SMD component that seems to be missing (blown off?). I think it may have been the fuse.

Funny, when I ran a continuity test on the amp board that died after I unscrewed/re-screwed the fan, there was no break in the circuit..so it's probably an IC that went out..

Yes, that's weird, maybe you hit it with static when you were handling it.

 

[GoldenVulture]

Re: DIY amp build: Done with the headshell ..now comes the tough part

The Brown component next to the blue arrow is the fuse. It says on the board what rating it is
There's only a couple of large SM resistors on the underside but apart from them , no other SM bits..

 

[Phantasmagoria]

Re: DIY amp build: Done with the headshell ..now comes the tough part

Static? ..did'nt really think there was anything to that. I mean I've heard you can kill things that way but never experienced it...

I just handle stuff indiscriminately. It's got me shocked a few times but that's it :lmao:

 

[Phantasmagoria]

Re: DIY amp build: Done with the headshell ..now comes the tough part

View attachment 95344 The Brown component next to the blue arrow is the fuse. It says on the board what rating it is
There's only a couple of large SM resistors on the underside but apart from them , no other SM bits..

There was another one of those parallel to the one that's there (grey arrow) ..that's what blew I think. It's under the board.

The top of the board is perfect. No visual signs of any damage..

 

[GoldenVulture]

Re: DIY amp build: Done with the headshell ..now comes the tough part

Static? ..did'nt really think there was anything to that. I mean I've heard you can kill things that way but never experienced it...

I just handle stuff indiscriminately. It's got me shocked a few times but that's it :lmao:

More likely to kill chips but I was just suggesting a possibility. I've killed chips in the past by getting my fingers all over the contacts.
Forgetting to discharge caps has got me a few times...hahaha:firedevil but I should be dead anyway, the amount of shocks I've had since about ten years old.

 

[Demanic]

Re: DIY amp build: Done with the headshell ..now comes the tough part

More likely to kill chips but I was just suggesting a possibility. I've killed chips in the past by getting my fingers all over the contacts.
Forgetting to discharge caps has got me a few times...hahaha:firedevil but I should be dead anyway, the amount of shocks I've had since about ten years old.

You must have built up a tolerance.

Sent from my Alcatel_5044C using Tapatalk

 

[GoldenVulture]

Re: DIY amp build: Done with the headshell ..now comes the tough part

View attachment 95346

There was another one of those parallel to the one that's there (grey arrow) ..that's what blew I think. It's under the board.

The top of the board is perfect. No visual signs of any damage..

Yes that's them. They have R100 on them on the 70volt version. They connect the high voltage to a regulator chip.
looking at that underside shot the HT comes from the cap to the right of those resistors which connect it to the regulating transistor to the left of them. They would work like a fuse I figure if you shorted one of the out puts.
Can you see the markings on the one left ? from what I can see they may be a different value.

You could plug it into some power and see if you have power at the cap side of those resistors. It'll be high volts if it has.

 

[Phantasmagoria]

Re: DIY amp build: Done with the headshell ..now comes the tough part

I'll check on that in a while when I'm able to. The remaining resistor seems to have blown as well .at least there's some metallic stuff in the center that's blocked out the printed value ..can only see what looks like a '5' at the end there (see pic)..



I'll have to check the other board..the one I'm using.

 

[Phantasmagoria]

Re: DIY amp build: Done with the headshell ..now comes the tough part

The resistors on my other board have 'R050' written on them..& yeah, there's power on the cap side. I guess it's matter of replacing those resistors & hoping for the best then? Does'nt SMD stuff have to be glued onto the board or something? (never tried soldering/replacing SMD thingy's before..)

 

[GoldenVulture]

Re: DIY amp build: Done with the headshell ..now comes the tough part

The resistors on my other board have 'R050' written on them..& yeah, there's power on the cap side. I guess it's matter of replacing those resistors & hoping for the best then? Does'nt SMD stuff have to be glued onto the board or something? (never tried soldering/replacing SMD thingy's before..)

No, just a pair of tweezers and a fine tip on your soldering iron. Probably nothing above 25 Watts or you might fry the Smd bits.
[You could probably solder on a couple of conventional 47 Ohm 1/4 watt resistors and see what happens. :saeek: there are through holes there on the PCB]

My other PS went out with a little crack last night. Checking it out today it appears some rectifying diodes that feed power to the + - 15v and the 12v section died. The tracks leading to them have heated up and come free of the circuit board and there's two dead diodes [ total short circuit ] I had my temp sensor boards hooked to the +15v.

We've had a spell of very hot days and the PS's have no fan on them. The amp modules were staying cool but no idea if the PS's were but I think maybe they've over heated. Both times it was working and then it wasn't. Last night was a lot more noticable.
I've already ordered another PS and now I'll have to do so again. I might install a fan or fans when I get the new ones.

 

[Phantasmagoria]

Re: DIY amp build: Done with the headshell ..now comes the tough part

Damn that sucks! I hope the fans in my enclosure can keep my PS board cool lol. It does'nt get very hot at all outside the enclosure but things can get pretty HOT here in the summer as well (not for a couple more months) and I could do without overheating problems. Do you think it may have had anything to do with running the two amp modules off just that one PS board of yours? I'm not sure what kind of load it handles..maybe that's what heated it up?

Yeah, I might give soldering those smd resistors back on the board a go, I got a strip of them off ebay

..my iron is 40 watts though. I'll probably have to get another.. or unplug it & let it cool down a bit first

 

[GoldenVulture]

Re: DIY amp build: Done with the headshell ..now comes the tough part

Damn that sucks! I hope the fans in my enclosure can keep my PS board cool lol. It does'nt get very hot at all outside the enclosure but things can get pretty HOT here in the summer as well (not for a couple more months) and I could do without overheating problems. Do you think it may have had anything to do with running the two amp modules off just that one PS board of yours? I'm not sure what kind of load it handles..maybe that's what heated it up?

Yeah, I might give soldering those smd resistors back on the board a go, I got a strip of them off ebay

..my iron is 40 watts though. I'll probably have to get another.. or unplug it & let it cool down a bit first

No, just be quick. Those resistors are pretty big for Smd types.

Do you think it may have had anything to do with running the two amp modules off just that one PS board of yours?

Not really. As the pic shows , the tracks that feed the power to the + - 15v and 12v over heated. They didn't actually burn up. The diodes they feed , two died I had two temp sensor [switches] attached there but I doubt they were drawing too much power. The diodes shorted which is why the tracks overheated.
We've had about a six day run of 37C [almost 100F] to 43C [almost 110F] and The air conditioner was struggling to keep the inside temp much under 30C, so the PS may have got a lot Hotter.
I'm going to replace the diodes and see if I can find anything else damaged and then see if it will fire up. Try a bit of trouble shooting.

 

[Phantasmagoria]

Re: DIY amp build: Done with the headshell ..now comes the tough part

No, just be quick. Those resistors are pretty big for Smd types.

:laugh2:

Not really. As the pic shows , the tracks that feed the power to the + - 15v and 12v over heated. They didn't actually burn up. The diodes they feed , two died I had two temp sensor [switches] attached there but I doubt they were drawing too much power. The diodes shorted which is why the tracks overheated.
We've had about a six day run of 37C [almost 100F] to 43C [almost 110F] and The air conditioner was struggling to keep the inside temp much under 30C, so the PS may have got a lot Hotter.
I'm going to replace the diodes and see if I can find anything else damaged and then see if it will fire up. Try a bit of trouble shooting.

Cool ..good luck with that :bigthumb: