Troubleshooting an humming WOPL : need help!

Coldsmoke

Coldsmoke

Journeyman
#63
Joined
Sep 8, 2014
Messages
243
Location
Brussels
Tagline
---
#63
There's less noise with the amp alone (I guess, bescause now I'm a bit lost...) or with the amp connected to the mixer (never tested before)
There's more noise with the amp connected to the preamp thant before.
 
laatsch55

laatsch55

Administrator,
Staff member
#64
Joined
Jan 14, 2011
Messages
75,030
Location
Gillette, Wyo.
Tagline
Halfbiass...Electron Herder and Backass Woof
#64
I would guess your pre amp is noisy...possibly the mixer too. Could you take the amp to pre-amp RCA cables and leave them plugged into the amp , un[plug them from the pre-amp and then short the ends of the RCA cable by taking a small wire wrapped around the middle prong and then to the ground shell of the cable?? What we are trying to do with that is eliminate any influence of the source...
 
Coldsmoke

Coldsmoke

Journeyman
#65
Joined
Sep 8, 2014
Messages
243
Location
Brussels
Tagline
---
#65
laatsch55 said:
I would guess your pre amp is noisy...possibly the mixer too. Could you take the amp to pre-amp RCA cables and leave them plugged into the amp , un[plug them from the pre-amp and then short the ends of the RCA cable by taking a small wire wrapped around the middle prong and then to the ground shell of the cable?? What we are trying to do with that is eliminate any influence of the source...
Click to expand...
You mean shorting Left Right channels or shorting each channel with its ground?
 
Coldsmoke

Coldsmoke

Journeyman
#68
Joined
Sep 8, 2014
Messages
243
Location
Brussels
Tagline
---
#68
Sorry guys it's almost 5:30 in the morning here, I feel a bit tired :toothy5:
Thanks A LOT by the way for your patience and incomparable help
 
Coldsmoke

Coldsmoke

Journeyman
#71
Joined
Sep 8, 2014
Messages
243
Location
Brussels
Tagline
---
#71
I think I'll leave it here for today, MANY thanks for your valuable help again : I feel we've made some progress here (that leaves me by the way with a shi*** p-amp...
I can't understand how that unit was working so well at salers place and so bad here :/

Talk to you soon I guess :D
 
G

gadget73

Journeyman
#73
Joined
Aug 29, 2014
Messages
465
Tagline
---
#73
try different RCA cables if you have not yet. The thing about the shields being cut makes me wonder if that is the problem. A different set would be a simple enough test.
 
laatsch55

laatsch55

Administrator,
Staff member
#74
Joined
Jan 14, 2011
Messages
75,030
Location
Gillette, Wyo.
Tagline
Halfbiass...Electron Herder and Backass Woof
#74
I also noticed on your Bridge Rectifier you have no snubbing capacitors.. A .01uf / 400 volt polypro or mylar caps accross all 4 lugs will help a bunch. This could be the source of the remaining hum....
 
Coldsmoke

Coldsmoke

Journeyman
#76
Joined
Sep 8, 2014
Messages
243
Location
Brussels
Tagline
---
#76
laatsch55 said:
I also noticed on your Bridge Rectifier you have no snubbing capacitors.. A .01uf / 400 volt polypro or mylar caps accross all 4 lugs will help a bunch. This could be the source of the remaining hum....
Click to expand...
Hello laatsch,
I've been earing to my amp today and I can say that it's MUCH better than it was before (confirmed by the second pair of ears that I've at home, meaning my girfriend's)
I've been trying to look around for the snubbing capacitors : I noticed you advise to put these in place in case of increase of the power caps values, but I'm not sure how these are supposed to be mounted... Can you give me a tip?
Btw, I gave an eye to the PL2000 service manual and I suspect all the diodes (Z1, Z2, Z3) and maybe Q1 to be a little tired... I'll try to source new parts and tell you about it.
 
laatsch55

laatsch55

Administrator,
Staff member
#77
Joined
Jan 14, 2011
Messages
75,030
Location
Gillette, Wyo.
Tagline
Halfbiass...Electron Herder and Backass Woof
#77
I don't advise putting these in place because of increased power supply cap values, but rather to cut down.on the switching noise if the diodes within the bridge rectifiers. One cap between each two post combination on the BR. 4 total...
 
Coldsmoke

Coldsmoke

Journeyman
#78
Joined
Sep 8, 2014
Messages
243
Location
Brussels
Tagline
---
#78
laatsch55 said:
I don't advise putting these in place because of increased power supply cap values, but rather to cut down.on the switching noise if the diodes within the bridge rectifiers. One cap between each two post combination on the BR. 4 total...
Click to expand...
ok, I have it, one cap in parallel with each diode. Please pardon my naive questions, I am trying to learn in the mean time : )
 
You must log in or register to reply here.
Top