#183 5th Generation ODS Skyliner. Layout/Schematic Discussion

Overdrive Special, Steel String Singer, Dumbleland, Odyssey, Winterland, etc. -
Members Only

Moderators: pompeiisneaks, Colossal

Post Reply
donvan
Posts: 259
Joined: Tue May 02, 2017 6:36 pm
Location: Dallas

Re: #183 5th Generation ODS Skyliner. Layout/Schematic

Post by donvan »

I some questions regarding the 4 .01 uF capacitors in the power supply:

1) I've never seen capacitors across each diode in a full wave bridge rectifier. Does anyone know the purpose of these caps? They aren't filter caps.

2) What type of caps are these and what voltage?

Thanks!
Bob Simpson
Posts: 299
Joined: Fri Sep 07, 2007 5:43 pm
Location: Lakewood, CO

Re: #183 5th Generation ODS Skyliner. Layout/Schematic

Post by Bob Simpson »

I believe, the .01 caps across the diodes are to help prevent switching noise from 1N4007-ish diodes. They are ceramic, 1000v, and unnecessary ( overkill? ) with "modern" ultra-fast UF4007 diodes. I think there is a discussion at el34world.com.

Bob Simpson
Please understand that IMO an answer to this question is of no practical relevance at all. - Max
User avatar
pompeiisneaks
Site Admin
Posts: 4222
Joined: Sat Jan 14, 2017 4:36 pm
Location: Washington State, USA
Contact:

#183 5th Generation ODS Skyliner. Layout/Schematic Discussion

Post by pompeiisneaks »

Moving the comments from the files section to a discussion topic. Please remember to discuss and ask questions in the "Discussion" topics and keep the files threads clean of questions and commentary.

This refers to the files topic: http://ampgarage.com/forum/viewtopic.php?f=5&t=13095
tUber Nerd!
donvan
Posts: 259
Joined: Tue May 02, 2017 6:36 pm
Location: Dallas

Re: #183 5th Generation ODS Skyliner. Layout/Schematic

Post by donvan »

Bob Simpson wrote: Tue May 09, 2017 2:54 pm I believe, the .01 caps across the diodes are to help prevent switching noise from 1N4007-ish diodes. They are ceramic, 1000v, and unnecessary ( overkill? ) with "modern" ultra-fast UF4007 diodes. I think there is a discussion at el34world.com.

Bob Simpson
Thanks Bob. That makes perfect sense.
User avatar
pompeiisneaks
Site Admin
Posts: 4222
Joined: Sat Jan 14, 2017 4:36 pm
Location: Washington State, USA
Contact:

Re: #183 5th Generation ODS Skyliner. Layout/Schematic Discussion

Post by pompeiisneaks »

BTW I should have replied on this too, Bob's 100% right, they're just a protection measure. They may be overkill but those caps are super cheap too, and not a big 'expense'. Yes modern diodes are much safer too, and maybe not as necessary anymore. I had a Vox AC100 that had this setup and I stripped out the board to build a Vox AC100/2 from back in the early 60's Vox Days in the chassis but I kept that diode/cap layout like the original did.

I've also since seen it in other power supplies (not all amp ones) and it seems to be used only sometimes.

~Phil
tUber Nerd!
Post Reply