Chandler Tube Driver Power Supply!?

[fattcamp]

Hey folks. Hopefully this isn't too out of left field. There is a similar post to this one on this very forum, so here goes.

I have a dead Chandler Late 80's Tube Driver (4-knob) and I need to replace the power supply. On the other DIYstompboxes thread, someone mentioned that Chandler originally suggested the Condor A-24V0-0A4-U12. They don't make those anymore unfortunately. I need to replace the psu and these are the specs: 120v / 60hz / 15w input, 24vac@6va output. I'm trying to do this on the cheap and I'm in Canada. Searching ebay/amazon/digikey is close but no cigar or rediculously expensive. Do I have to follow these exact specs or if I'm close with the specs, do you think it would be ok? In other words.. a 20-watt for example or a higher VA on the output. I'm not good with power but I'm good with a soldering iron. Any help would be much appreciated. Cheers!

-Fattcamp

[PRR]

In general, small AC-output supplies are going out of style (and stock) because of new efficiency regulations.

Yes, you can use more VA/power, don't go overboard.

If you are making Line Connections, please know what you are doing! A pre-made and tested wall-wart is safer than most home-brew.

[Mark Hammer]

The schematics I have show a 12.6VAC transformer, that gets divvied up into +/-12V via diodes.  In one instance full-wave rectification, and in other drawings, half-wave.

Steve Daniels sent me an Eleca Tube Distortion, that is a clone of the BK Butler Tube Driver, that is very close, if not identical to, the Chandler unit.  The wallwart is a very basic 12VAC/1A unit.

[anotherjim]

I don't get it!
By "power supply", do you mean the transformer? Or does it have an external power brick?
Most examples I can find have an internal transformer which does appear to be only 6VA size. A 6VA 12-0-12v or 24v secondary transformer should be easy to buy.

[fattcamp]

Sorry for being late to my own party folks! New Dad here... weeks & months pass by in the blink of an eye. I ended up purchasing a replacement wall-wart through Digikey and I'm just now finding time to look at it. Since I'm an idiot and was too focussed on tech specs, I completely overlooked the fact that it's a center-tapped and I only purchased a 2 wire version. Am I screwed and have to order another one or is there a way I can make this one work without much hassle? If I need to start over, any recommendations on getting an appropriate replacement transformer power supply that's 24VAC @ 6VA Output / 15w Input? You used to be able to get the Condor A-24VO-0A4-U12 but it's not available anymore. I purchased this from Digikey (https://goo.gl/BnUrrw). I've taken a look around online but not having much luck.

[PRR]

Congratulations!

Yes, a 24VAC no-CT is probably wrong. (There must be some reason they paid extra for a CT.)

This has gone on long enough. I do not recall any details of that beast. Do you have links to specs, circuit diagrams, power-wart discussions on other forums?

[PRR]

https://www.ebay.com/i/152474535427

[printer2]

No centertap seems fine.




Seems there is a one tube model with a IC, mind you that one has its own power transformer in the pedal.

[PRR]

That plan has 5 knobs and claims to be a "Mini Boogee".

Fattcamp has a "Chandler Late 80's Tube Driver (4-knob)".

They may be related; or not. Is there more information?

[amptramp]

The red LED will always be on regardless of the state of the footswitch.  In one circuit I built, a RED LED had a voltage drop of 1.88 volts which is typical.  In another circuit, a green LED dropped 2.05 volts and this is also typical.  Regardless of the state of the switch, the red has the lowest voltage and will prevent the green from turning on.  You need to switch the red, not the green and obviously the switch should be wired to make connection in the opposite state.

[electrosonic]

I own the same pedal. When my power supply died, I couldn't find a 12v AC wall wart with a center tap. I modded the power supply section so I could use a non center tap 12v AC wall wart.

The pedal is on loan to a friend right now, when I get it back I should open it up and have a look and refresh my memory as to what I altered.

Andrew.

[amptramp]

You could always use two 6 VAC wall warts.  Connect centre pin of one to the shell of the other and you should have the same effect as a 12 VAC wall wart with a centre tap.

[printer2]

If there is room in the case you could do a virtual centertap for the IC's.

[PRR]

> do a virtual centertap for the IC's.

_If_ that is the right plan; the problem is that the 12V heater hangs on ONE side of the +/-16V supply.

So 1612mA on +16V, 2mA on -16V.

To balance that we might try a divider with 10X the unbalanced current. 1,500mA or 1.5A. This leads to a VERY large wall-wart.

Add "another heater" on the other side. 100 Ohms 5W is close enough. This doubles the power demand and heat; why the original opted for a CT. Need 10VA rating. But non-CT 24VAC is much easier to find today.

You could alternatively just shove +/-15V DC into the "AC" terminals. The rectifier is now pointless but does no harm. +/-15VDC *may* be easier to find.

[printer2]

I didn't even look at the schematic that close, that sucks having the heater hanging off the one side. I would get a step down converter from China and run across the whole supply.

[PRR]

... 1612mA on +16V, 2mA on -16V.....

Um, somebody can't count/type.

162mA one side, 2mA other side. (Approximately.)

[fattcamp]

Thanks for all of the info guys. Unfortunately I don't think I have the time to play around with the circuit unless it was a super simple fix. That ebay link looks like what I need but it's not available on ebay.ca... or similar products are going to come to at least $50. Since I'm already $30 into the wrong power supply, not sure if I can justify that purchase right now, but I really appreciate everyone's help. I'll get a replacement eventually!

-Dave

[printer2]

Available in Canada. Just hang it across the two filter capacitors and connect to the tube heater, either 12.6V or 6.3V.

https://www.ebay.com/itm/LM2596S-DC-Step-Down-Regulator-Power-Module-Buck-3-2-40V-To-1-25-35V-3A-Adjust/153112254285?hash=item23a633974d%3Ag%3Ap%7EMAAOSwpAlbVxS-&LH_BIN=1