The SLB (Smooth Like Butter) Active Rect/CRC/Cap Mx Class A Power Supply GB

[Kokanee]

Thanks Hugh,

I will keep up with this, just a break and working on my FH9HVX, Xmas amp, and the Simple Quasi. These have all played music, and only have some slight problems to fix up ( I hope ). Working on chassis for them also with wood and metal combinations.

Any idea's on where to start trouble shooting around the SA1943 to find why it is only dropping 1.0 Volts. It is brand new.

Best regards,
MM

 

[AKSA]

What is the Vbe of the A1943 in operation, Myles?
Is it passing current to the amp; or to a 1.6A load?

Hugh

 

[Kokanee]

Thanks for the starting point Hugh. Once I get back to working on the AN39/SLB's, I will check this out first. Right now my bench over-floweth with other projects. I was testing with about 28V into a 25 ohm resistor, so around 1A load theoretically. I never checked for current at the resistor on the heatsink, just noticed it and the transistor were warming up nicely. I will get back on this thread later and check things out.

Question: With DMM and testing SA1943 only, would I check current across the load resistor ? if using the amp for the load, would I check for current from V+ on the amp to amp ground ?

Sorry for the basic theory, just want to be safe with current.

Just got our 1st dump of snow this winter. I hope you have a great summer. Should be entertaining once I get back to these rascal's.

Best regards,
MM

 

[AKSA]

Yes Myles the voltage across the load resistor plus the VCE on the series pass regulator transistor should total the voltage seen at the rectifier and filter cap.
A 1A test current should be fine for testing and if the reg A1943 is warming up nicely you are almost there.
Hot today here, 36C (96F)!

Hugh

 

[xrk971]

First mild flurry of snow here in the DC area. Maybe I’ll get back in the lab to play with an amp again. There is an AN that a friend of mine had another friend build for him and it has a burned out MOSFET flying lead I suspect. Will need to crack that open and check it out.

I just realized that I am sold out of SLB Dual Rail PCBs again. These are probably one of the most consistently moving sellers in my shop.

What is your latest project that you are working on Hugh? (@AKSA ) Great to hear from you.

 

[AKSA]

Hi X,
Nice to hear from you too!
I'm working on two versions of a power buffer, a tube and a semiconductor preamp.
But my daughter from NYC has just returned home and we have spent a wonderful two weeks with her and her new baby.
One could say that in my dotage I'm enjoying the only version of immortality we are granted! It is wonderful to hand back the child to her parents!
Hugh

 

[xrk971]

Enjoying grand kids is perhaps the best perk of being a parent. Glad you got to see your daughter for the holidays.

 

[xrk971]

A new batch of dual rail SLB's has just been ordered - I should have them back in stock in a few weeks.

 

[darrr]

Great because I was just going to ask about availability

 

[turion64]

X....are there any more SLB single rail boards available ?


Thanks, Pete

 

[darrr]

When I check if there are already double , I see a single rail is available on Etsy

 

[turion64]

Yes, you are correct...the picture shows a double rail but the choice menu allows one to order a single rail.

Thank you

 

[Dneu2011]

Quick question about setting the trim pot on my single rail SLB boards.

I’ll be using an Antek AS-3220 to run an SLB on each secondary with an amp camp board for each SLB.

I see I need to adjust the trim pot back 3 Volts. how do I determine the voltage without adjustment to know to set it down 3V? Or maybe I misunderstood an easy way to do this without a scope.

Thank you.

 

[poseidonsvoice]

I see I need to adjust the trim pot back 3 Volts. how do I determine the voltage without adjustment to know to set it down 3V? Or maybe I misunderstood an easy way to do this without a scope.

See posts 1481-1491. The actual adjustment range of the pot is very small, about 1V as I recall. So doing it with a DMM is not what I would recommend (since you cannot visualize the ripple). I would have a scope on the output of the SLB supply WHILE it is connected to the amplifier load. What you are looking for on the scope is the ripple voltage of your V+ (and/or V- if using the bipolar version). You adjust the pot for the most minimum ripple voltage. Then you remove the pot, measure the value and replace that same value with a fixed resistor (optional).

This is more of a tweak of the SLB rather than an absolute requirement. Most folks build the SLB with the pot at a center value and forget about it, which is fine.

Best,
Anand.

 

[vanofmonks]

@xrk971 do you have an update on when the new batch of dual rail SLBs will be available?

 

[xrk971]

They should arrive any day now - I think should be available to place orders.

 

[MFRD]

Hi all, what are the dimensions of the dual rail PCB? I'm looking at this for a retrofit project.

Apologies for what is most likely a repeat question, but google didn't have an answer 🙂

Thank you!

 

[poseidonsvoice]

@MFRD

From the 1st post of this thread:

100mm X 142.5 mm with mounting holes at 4.5mm from the corners.

Best,
Anand.

 

[MFRD]

Thank you Anand. The PCB would fit in my project.

I did not see the dimension lines on my phone display, sorry about that

 

[darrr]

They should arrive any day now - I think should be available to place orders.

Hi🙂 Only single rail is still available…