No, as I have indicated on the pic! You see the small blue arrows at the front, down left and right!?
The left side 6 caps are the neg side and the right 6 caps are pos side.
Anything wrong with it?
It may help you as it did for me quite a few times...
Hide the original schematics
Draw circuit exactley from your actual build
And then compare the 2
do not cut corners as I did a few times exitment to get the thing working make anybodi
blind to the obvious
From the picture L side + rectifier to + of caps and then if the print on the caps is corect indication of polarity (can't see + - sign) you are connecting the resistors to the - of the caps
From the picture it looks like you shuld rotate the caps 180 deg
Same all for negs rail
would not be the first time that this happens some how I am certain of it
done it myself
Hide the original schematics
Draw circuit exactley from your actual build
And then compare the 2
do not cut corners as I did a few times exitment to get the thing working make anybodi
blind to the obvious
From the picture L side + rectifier to + of caps and then if the print on the caps is corect indication of polarity (can't see + - sign) you are connecting the resistors to the - of the caps
From the picture it looks like you shuld rotate the caps 180 deg
Same all for negs rail
would not be the first time that this happens some how I am certain of it
done it myself
Bks is right to be concerned.
The orientation of the caps does not look right.
Starting with the near row of 4 caps.
The two middle terminals are labeled. 4 in from left is -ve, 5 in from left is +ve.
Number the terminals 1 at extreme left and 8 at extreme right.
The capacitor terminals at each of the connections 1 through to 8 are.
1=-
2=+
3=+
4=- , as labeled
5=+ , as labeled
6=-
7=-
8=+
Are you using a dual bridge rectifier fed from a dual secondary transformer?
rectifier left -ve goes to 1, rectifier left +ve goes to 2.
rectifier right +ve goes to 8, rectifier right -ve goes to 7.
Relabel the StarGND as Zero Volts. This is not the Audio Ground.
The 3 wires from the PSU, +ve, 0, -ve, are conveniently close together to combine into a twisted triplet.
The orientation of the caps does not look right.
Starting with the near row of 4 caps.
The two middle terminals are labeled. 4 in from left is -ve, 5 in from left is +ve.
Number the terminals 1 at extreme left and 8 at extreme right.
The capacitor terminals at each of the connections 1 through to 8 are.
1=-
2=+
3=+
4=- , as labeled
5=+ , as labeled
6=-
7=-
8=+
Are you using a dual bridge rectifier fed from a dual secondary transformer?
rectifier left -ve goes to 1, rectifier left +ve goes to 2.
rectifier right +ve goes to 8, rectifier right -ve goes to 7.
Relabel the StarGND as Zero Volts. This is not the Audio Ground.
The 3 wires from the PSU, +ve, 0, -ve, are conveniently close together to combine into a twisted triplet.
Last edited:
While dazed2 get sorted progress update.
Been working on channel 2
I have mentioned before how 2 flat surfaces stick togheter
I can say that it is true as I have been honing the heat spreaders to the heat sinks made a right mess of the anodised layer but by rubbing the 2 togheter with paint scratch remover and Bicarb of soda (baking powder) I got one of them spreaders to stick to the heat sink it takes quite a bit of effort to take the 2 appart.
the all idea is to improve thermal coupling.
Done half as god job on the second one and then got bored with it but should give me sometink to mesure up and compare tomorow
Apart from that chanel one is as before but the MCP 0.47 R get prety hot 70 C I am dropping 0.92 volts accros them and I am a bit worry about reliability
May have to change those to 0.2
Any sugestion in this regard?
Been working on channel 2
I have mentioned before how 2 flat surfaces stick togheter
I can say that it is true as I have been honing the heat spreaders to the heat sinks made a right mess of the anodised layer but by rubbing the 2 togheter with paint scratch remover and Bicarb of soda (baking powder) I got one of them spreaders to stick to the heat sink it takes quite a bit of effort to take the 2 appart.
the all idea is to improve thermal coupling.
Done half as god job on the second one and then got bored with it but should give me sometink to mesure up and compare tomorow
Apart from that chanel one is as before but the MCP 0.47 R get prety hot 70 C I am dropping 0.92 volts accros them and I am a bit worry about reliability
May have to change those to 0.2
Any sugestion in this regard?
Mallard,
It would help us, help you, if you took the photo in post 802, and placed a "+" sign on the pic for each of the caps, showing us the positive cap terminal. I think we all are unable to read the markings on the each cap, for us to figure that out. Objective, of course, is for us to determine if you two cap banks are wired properly. Close-up pics of your rectifier wiring would be useful, too.
Thanks
It would help us, help you, if you took the photo in post 802, and placed a "+" sign on the pic for each of the caps, showing us the positive cap terminal. I think we all are unable to read the markings on the each cap, for us to figure that out. Objective, of course, is for us to determine if you two cap banks are wired properly. Close-up pics of your rectifier wiring would be useful, too.
Thanks
Hey, Bksabath...... (Looks like you're having fun with your amp!)
I think you're right, but I wasn't able to make out all the markings on each of the caps. Just wanted Mallard to confirm. If it's not a cap bank problem, next thought would have to be the rectifier-cap hook up......
Yeah I don't seem to be able to post a pic for some reason. The "attach files" section doesnt seem to have a pull down? I tried to add the + and - on the pic Mallard posted. Anyways Mallard what CanAm said... post the pic where you have all the caps labeled + and -. If its not a cap problem then its a rectifier connection issue. Power up just the rectifier and make sure which is + and which is - Note : even more odd, my type spacing isn't working. I can't add spacing in between paragraphs.
Last edited:
That is an extremely common problem. I agree, however, that verification of the capacitors is the step for right now.
There is some talk on the Forum Problems section that there is a bunch of maintenance and upgrades going on right now, and functionality is down. The IMG stuff seems to be one of the causalities. (Hopefully only temporarily.)
Last edited:
Hi Ken
Yes load of fun...
With 2 A mosfet 0.92 volts accross R11 0.47 R getting realy hot
spec sheet shows derating and 1000 Hours at 70 C
((.92 X 2 ) /0.47 ) = 3.9W
I may have to change the Futabas MPC74 to 0.22
Hows yours R11 doing you using Papa Spec 3 Watters?
Heard that MPC sound beter hot but....
Any comments?
Yes load of fun...
With 2 A mosfet 0.92 volts accross R11 0.47 R getting realy hot
spec sheet shows derating and 1000 Hours at 70 C
((.92 X 2 ) /0.47 ) = 3.9W
I may have to change the Futabas MPC74 to 0.22
Hows yours R11 doing you using Papa Spec 3 Watters?
Heard that MPC sound beter hot but....
Any comments?
Hi Guys,
thanks a lot for your hints! Unfortunately I'm currently travelling in Netherlands for 3 days so I can't make any additional picture right now.
What's clear, the position of the print on the cap is not linked to the position of the + or -
But I modified the existing picture with polarities of the caps, see attached!
The pic with the bridge will follow soon.
Cheers,
Mallard
thanks a lot for your hints! Unfortunately I'm currently travelling in Netherlands for 3 days so I can't make any additional picture right now.
What's clear, the position of the print on the cap is not linked to the position of the + or -
But I modified the existing picture with polarities of the caps, see attached!
The pic with the bridge will follow soon.
Cheers,
Mallard
My F5's doing fine, Bksabath..... I'm biased (or my amp is), stable (or my amp is), and I'm listening to fine music. I'm sitting at 1.3 amps thru R11 and R12, and everything is cool (and that includes the heatsinks, which are warm, but not hot). I may tweak bias later, after I check the price and availability of potentially-needed replacement MOSFETs....
