BlackStar - HT-DUAL

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Re: BlackStar - HT-DUAL

Postby teemuk » 24 Aug 2009, 17:28

Well, I managed to figure it out by consulting Dirk's sketch. The switch and the gain pot was the only spot missing from the control board.

I'm almost done with the board holding the SMPS and some gain stages and then I'll proceed to the board that holds the tube board, jacks and footswitches.

So far, the schematics posted here seem to have some errors. Some components seem to be missing from Dirk's sketches and some seem to have incorrect values. The circuit doesn't simulate right in SPICE, which i use to test all dubious stuff. (the resulting frequency response is very odd) Here's my sketch (see atachment): It seems to be more correct. I can't verify it for 100% but it seems to simulate correctly and produce a rather typical mid-scooped frequency response.

The SMPS schematic posted here already also has a tiny error. The 120-ohm resistor tapped to +22V, followed by a 18V Zener regulator should not be in series with the choke. This regulated circuit is just a steady DC supply for the pin 7 - not a takeoff point for the main SMPS current. The choke should really connect the point before that resistor.

I'll post more as I advance. At the moment it seems I might have some problems seeing what's below the tube but I will know for certain once I start tracing that board.
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Re: BlackStar - HT-DUAL

Postby Dirk_Hendrik » 24 Aug 2009, 18:12

teemuk wrote:Some components seem to be missing from Dirk's sketches and some seem to have incorrect values.


Might that be the other way around? ;)
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Re: BlackStar - HT-DUAL

Postby Dirk_Hendrik » 24 Aug 2009, 18:13

Dirk_Hendrik wrote:
teemuk wrote:Some components seem to be missing from Dirk's sketches and some seem to have incorrect values.


Might that be the other way around? ;)

(doing that tracing with the real thing in front of me)
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Re: BlackStar - HT-DUAL

Postby teemuk » 24 Aug 2009, 19:31

Maybe we have different circuit revisions then. In the layouts I’m looking pin3 of IC4 runs to resistors R33 and R34, not straight to ground. Your schematic seems to be missing resistors R33 and R34 completely. :?:

Furthermore, VR4a is disconnected and the two outputs from VR6 wipers run to pins 4 and 5, not to 4 and 1.

You have labelled CON8_5 as ground while in the board photos I have ground is obviously CON8_1. CON8_5, as said, carries one of the signals from the VR6 wipers. Also, C31 and R47 are not in series since the adjoining node runs to IC5 pin 3.

Etc.

Anyway. Maybe the boards are different. I'm not always too good with colours so my interpretation of component values may have some issues. Sometimes it's just too damn hard to distinct yellow from orange or red from brown. :oops:
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Re: BlackStar - HT-DUAL

Postby Dirk_Hendrik » 24 Aug 2009, 20:16

teemuk wrote:Maybe we have different circuit revisions then. In the layouts I’m looking pin3 of IC4 runs to resistors R33 and R34, not straight to ground. Your schematic seems to be missing resistors R33 and R34 completely. :?:

Furthermore, VR4a is disconnected and the two outputs from VR6 wipers run to pins 4 and 5, not to 4 and 1.

You have labelled CON8_5 as ground while in the board photos I have ground is obviously CON8_1. CON8_5, as said, carries one of the signals from the VR6 wipers. Also, C31 and R47 are not in series since the adjoining node runs to IC5 pin 3.

Etc.

Anyway. Maybe the boards are different. I'm not always too good with colours so my interpretation of component values may have some issues. Sometimes it's just too damn hard to distinct yellow from orange or red from brown. :oops:


;)
I'll try to check your suggestions tomorrow.
As for the colorcodes... I know, they can be tough
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Re: BlackStar - HT-DUAL

Postby teemuk » 25 Aug 2009, 01:33

More schematics...
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Re: BlackStar - HT-DUAL

Postby himister » 25 Aug 2009, 03:58

Sorry guys for barging in the middle of the tracing...
Couple of small insights in the SMPS testing area.

I made a few changes in values of components but I just get rid of the "whining" sound supply made.
As the Steve said that he will try to "increase the oscillator frequency above human hearing" that's what I just did. :mrgreen: Whine is present for a just a second when SMPS is engaged.
To be honest I'm not that much in SMPS expertize but I understand the basics and I just make a conclusion by making a mistake... :slap: I changed the 33n cap to 330n and whine pitch frequency has lowered, so I realized my mistake.. but got an idea also. So I tried to change the 33n cap to 10n and suddenly whine's gone. Higher switching frequency. :D Guess I have also changed whole cycle of the PWM controler but for now I don't see any stress on it.
I tested components for heating and there's none, except small rise in temperature of the 150R 2W resistor in the positive supply rail. Nothing to be concerned. Also few components are different, fast recovery diode is still TURBOSWITCH ULTRA-FAST HIGH VOLTAGE DIODE STTA812D. I know it sounds silly to use something like that but it worked for me so I left it there. Filter cap in the supply input is 100uF and HV filter caps are smaller 4.7uF 400V. MOSFET is IRF840 just to be on the safe side and inductor I used is marked as the 470K. I used an old laptop battery charger SMPS rated at 17V 1.3A for the DC supply, I measured 16V at the clamps. I get close to 285V unloaded from the Blackstar SMPS but no whining bitchin'! :lol:

If anyone interested few info tips from the datasheet of UC3843AN:
Features
• Low Start Current 0.2mA (typ)
• Operating Range Up To 500KHz
• Cycle by Cycle Current Limiting
• Under Voltage Lock Out With Hysteresis
• Short Shutdown Delay Time: typ.100ns
• High Current Totem-pole Output
• Output Swing Limiting: 22V

Description
The UC3842A/UC3843A are fixed PWM controller for Off-
Line and DC to DC converter applications. The internal circuits
include UVLO, low start up current circuit, temperature
compensated reference, high gain error amplifier,
current sensing comparator, and high current totem-pole output
for driving a POWER MOSFET. Also UC3842A/
UC3843A provide low start up current below 0.3mA and
short shutdown delay time typ. 100ns. The UC3842A has
UVLO threshold of 16V(on) and 10V(off). The UC3843A is
8.4V(on) and 7.6V(off). The UC3842A and UC3843A can
operate within 100% duty cycle.


That's all for now...gone for more testing.

Cheers :thumbsup
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Re: BlackStar - HT-DUAL

Postby Dirk_Hendrik » 25 Aug 2009, 08:07

teemuk wrote:. The circuit doesn't simulate right in SPICE, which i use to test all dubious stuff. (the resulting frequency response is very odd) Here's my sketch (see atachment): It seems to be more correct. I can't verify it for 100% but it seems to simulate correctly and produce a rather typical mid-scooped frequency response.



quick Q;
How come in "my" blackstar the treble control is a dual pot and a single in yours?
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Re: BlackStar - HT-DUAL

Postby bajaman » 25 Aug 2009, 08:10

Thanks for barging in Mike :wink:
hello to teemuk and Dirk of course :D
IMPORTANT INFORMATION

Thanks to teemuk and himister - I am such a fool - I have made three mistakes in my Blackstar SMPS drawing which I have corrected - please refresh your browser, here is the corrected schematic.

Image

Teemuk is indeed correct - the inductor in parallel with the 10k resistor connects BEFORE the 150 ohm 1 watt resistor :oops:
Himister has solved the whining issue, which encouraged me to double check the gut shot pictures and surprise surprise, the 33n capacitor mentioned IS ACTUALLY a 3.3n capacitor :oops: :oops: :oops:

Finally the IN4007 diode connected to the drain of the IRF830 mosfet is WRONG - it will not work - in fact i burnt out an inductor and fried a mosfet when I first built this supply. 1N4007 is just TOO SLOW for the mosfet switching speed/
The correct diode ( I can verify this - i lifted it off the board :wink: ) is a 1N4937 - a high speed fast switching diode rated at 2A.

Please accept my apologies for these mistakes.
This is now a good high speed switching supply and I shall be investigating it further in one of my experimental twin mini tube circuits.

Finally teemuk - i have many drawings in CorelDraw format showing the track layers and component placement on both sides of all the boards. Please email me and I will send them all to you, or if you do not have CorelDraw let me know and I will send high res *.png files - you should be able to complete the schematic from them no trouble.
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Re: BlackStar - HT-DUAL

Postby bajaman » 25 Aug 2009, 09:03

Update:
Just spent the last half an hour annoying the neighbours testing my twin tube overdrive with the Blackstar power supply - no hum, no hiss or whine (well there was some hiss, but nowhere near a Peavey 5150!!!).
power supply performed faultlessly - no overheating issues - I am using a 3A fast rectifier diode in place of the 1N4937 and an IRF830 with a 470uh choke from Mouser or Digikey (forgot who I got it from :oops: )
thanks himister and teemuk for pointing me in the correct direction :applause:
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Re: BlackStar - HT-DUAL

Postby Dirk_Hendrik » 25 Aug 2009, 09:14

Sorry. Plain out of planes.

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Re: BlackStar - HT-DUAL

Postby bajaman » 25 Aug 2009, 10:24

Here is the PCB and component layout for my working smps - 1200 dpi.
missing is the 1N4007 input polarity protection diode and output filter capacitors.
Nominal input voltage is +22v DC.
WATCH OUT - THIS IS A VERY HIGH VOLTAGE OUTPUT - 270 volts DC output.
Definitely Not for novices
You have been warned - please take care

http://freestompboxes.org/members/bajam ... layout.png

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Re: BlackStar - HT-DUAL

Postby briggs » 25 Aug 2009, 11:03

bajaman wrote:Here is the PCB and component layout for my working smps - 1200 dpi.
missing is the 1N4007 input polarity protection diode and output filter capacitors.
Nominal input voltage is +22v DC.
WATCH OUT - THIS IS A VERY HIGH VOLTAGE OUTPUT - 270 volts DC output.
Definitely Not for novices
You have been warned - please take care

members/bajaman/Baja/Blackstar/Blackstar%20HT%20power%20supply%20PCB%20and%20layout.png

cheers
bajaman


Whap amp supply would you recommend? 1A enough to drive a couple of tubes + heaters?
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Re: BlackStar - HT-DUAL

Postby frequencycentral » 25 Aug 2009, 11:21

bajaman wrote:WATCH OUT - THIS IS A VERY HIGH VOLTAGE OUTPUT - 270 volts DC output.
Definitely Not for novices
You have been warned - please take care


Hehehe - my SMPS has 'got my attention' a couple of times. Tip - disconnect power before tinkering with breadboard while holding guitar - Rotosound R10 Roto Yellows are excellent electrical conductors.

Though I prefer my high voltage warning:

HIGH VOLTAGE WARNING: The electrons used in this circuit will steal your guitar, sleep with your girlfriend and leave you for dead. I was personally pronounced clinically dead to medical science fiction on three occasions while working on this circuit. Fortunately paramedics were on hand to revive my still twitching corpse. You may not be so lucky. If working on this circuit with the power engaged, keep both hands in your pockets. Always use a condom.
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Re: BlackStar - HT-DUAL

Postby briggs » 25 Aug 2009, 11:31

frequencycentral wrote:
bajaman wrote:WATCH OUT - THIS IS A VERY HIGH VOLTAGE OUTPUT - 270 volts DC output.
Definitely Not for novices
You have been warned - please take care


Hehehe - my SMPS has 'got my attention' a couple of times. Tip - disconnect power before tinkering with breadboard while holding guitar - Rotosound R10 Roto Yellows are excellent electrical conductors.

Though I prefer my high voltage warning:

HIGH VOLTAGE WARNING: The electrons used in this circuit will steal your guitar, sleep with your girlfriend and leave you for dead. I was personally pronounced clinically dead to medical science fiction on three occasions while working on this circuit. Fortunately paramedics were on hand to revive my still twitching corpse. You may not be so lucky. If working on this circuit with the power engaged, keep both hands in your pockets. Always use a condom.


You should smack the SuperFly with 260+ V and see what happens Rick... MORE CRUNCH, MORE VOLUME!
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Re: BlackStar - HT-DUAL

Postby bajaman » 25 Aug 2009, 11:55

What amp supply would you recommend? 1A enough to drive a couple of tubes + heaters?

yes, from memory the Blackstar used a 800mA AC supply
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Re: BlackStar - HT-DUAL

Postby himister » 25 Aug 2009, 18:50

bajaman wrote:Here is the PCB and component layout for my working smps - 1200 dpi.
missing is the 1N4007 input polarity protection diode and output filter capacitors.
Nominal input voltage is +22v DC.
WATCH OUT - THIS IS A VERY HIGH VOLTAGE OUTPUT - 270 volts DC output.
Definitely Not for novices
You have been warned - please take care

http://freestompboxes.org/members/bajam ... layout.png

cheers
bajaman



Thanks Steve for the effort...really good job! :thumbsup

Would you be so kind to post or send me the SL5.LAY file of the Blackstar SMPS.
I guess you've exported the PNG from it. It's much easier for me to make pdf or postscript file for filming.

Thanks in advance.

Cheers :wink:
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Re: BlackStar - HT-DUAL

Postby frequencycentral » 25 Aug 2009, 20:00

So Steve - how much current can you squeeze out of the BlackStar SMPS?
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Re: BlackStar - HT-DUAL

Postby bajaman » 25 Aug 2009, 22:54

Hi Rick
I have not got that far yet :wink:
I think the current supply is dependant on the wattage of the inductor and the current capabilities of the mosfet - for higher currents it would need to be on a heatsink. Of course you will need a 22v DC voltage source capable of supplying the extra current too.
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Re: BlackStar - HT-DUAL

Postby teemuk » 27 Aug 2009, 15:14

Finally, they are completed!

Thanks to everyone who participated in helping me out to get these done. :applause:

I also must apologize that the schematics I posted previously contain errors. The smart ones likely have figured out the obvious ones already. :oops:

Anyway, these should be rather accurate.
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