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Old 12th Oct 2017, 11:20 am   #21
'LIVEWIRE?'
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Default Re: What is a CSN60?

The PWM controller is a TL494CN, Chris, so I can easily find data for that, but the tiny 6-pin SMD chip associated with the CS1N60 may be a different kettle of fish. I've already identified the connections to 3 of the pins of that device. These connect to the source & gate of the 1N60 via series resistors (to be precise the pin connected to the source is effecively grounded via the 2R0 resistor via a series R of510 ohms). Two of the remaining pins must surely be Vcc+ (or Vdd+) and ground, so I'm (slowly) getting there! Thanks again to you and other members for your help.
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Old 12th Oct 2017, 11:59 am   #22
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Default Re: What is a CSN60?

The TL494CN is a fairly prehistoric controller chip, and was never really intended to drive MOSFETs - it's from the bipolar era and has an NPN output transistor which makes a poor show of driving MOSFET gates. The little six-pin thing is likely, therefore, to be a MOSFET gate driver, something like this:

http://uk.farnell.com/diodes-inc/zxg...3-6/dp/1549141

Does the pinout match? Does the device have all 6 pins fitted? There are also quite a lot of gate drivers available in SOT23-5 packages, like this one:

http://www.ti.com/lit/ds/symlink/tps2818-ep.pdf

First thing to do is check whether the TL494 and driver have power or not. Check with a multimeter across the relevant pins shown on the chip data sheets. Be aware that all this stuff is on the primary side and therefore to be considered live, unless you're running the Beat Box from an isolating transformer.

If they have power, my next move would be to see what's coming out of the TL494. I'd use a scope for this, but with the Beat Box powered from an isolating transformer and the 0V rail on the primary side grounded. If you don't have an isolating transformer, don't try it! Failing that, voltage measurements from primary side 0V to the various pins on the TL494 might tell us something.

Circuits like this often have a startup arrangement involving a high-value resistor (100k-1M, usually) which goes open-circuit because it spends its life with nearly 300V across it. Sometimes there's a small electrolytic that's involved in startup, too, and those fail, occasionally with catastrophic consequences (cf some Samsung and Panasonic VCR power supplies).

Take care
Chris
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Old 12th Oct 2017, 12:39 pm   #23
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Default Re: What is a CSN60?

It's similar to those, Chris, but not exactly the same as either.
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Old 12th Oct 2017, 1:20 pm   #24
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Default Re: What is a CSN60?

If you are new to SMPSUs you need to remember that the gate of a MOSFET gate is made of the same stuff as computer memory.
It will "remember" what way round the leads on your diode tester were when testing the gate for quite a few minutes. The FET will remain in the ON state as a legacy of your previous test.
You need to touch the leads on a conductive surface such as a wet finger between tests to prevent confusion.
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Old 22nd Oct 2017, 10:33 pm   #25
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Default Re: What is a CSN60?

Attached is a photo of the PSU used in the Dr. Dre Beatbox. It's similar in principle to most other SMPSUs, though instead of an optoisolator, the rectified HT o/p, smoothed by two 220uf/200v. Electrolytics in series, is coupled to the primary of the bigger of two transformers via a 2uf 250v Metalized poly. capacitor. To reply to your post, Refugee, I didn't think about that when testing the FET, but thanks for reminding me. I've since discovered that the 2uf capacitor is faulty - it reads much lower in value than that.
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Old 23rd Oct 2017, 12:00 pm   #26
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Default Re: What is a CSN60?

I have traced out part of the circuit, mainly the primary side. Hopefully my sketch is readable. As far as I can see the two transformer primaries are supplied via C16 from the junction of the two 220uf electrolytics, though quite how this works I'm not sure. The diodes in the bridge checked out OK 'cold', and the HT voltage is present, but no DC o/p either at CN4, where I would expect to find maybe 50v, given the voltage ratings of C20 & C30, or at CN3, at which there is meant to be + &- 7vDC. I've trawled the 'net in vain to find either a circuit diagram, spare parts, or a replacement PSU PCB. Tracing the complete circuit will take ages, though I do have data for the TL494 PWM IC. BTW the upper end of the top transformer primary connects to the drain of T7 and the gate of T6. These are A13TA((J13009-2) devices in TO-220 packages.
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Old 23rd Oct 2017, 12:26 pm   #27
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Default Re: What is a CSN60?

A few thoughts, which may or may not be useful:

This is beginning to look like the insides of a PC power supply. The two 220uF electrolytics are in series across the rectified mains, which is a common arrangement: it means that adding one wire link turns the bridge rectifier and two capacitors into a voltage doubler and the whole thing will then run from 110-120V.

Judging by what I can see of the secondary rectifier arrangements (the two diodes followed by an inductor and capacitor), plus the snubber across transformer primary, this may be a forward-mode converter rather than the flyback topology that most low-power consumer electronics use. That's what makes it similar to a PC power supply. If this is the case, then T6 and T7 may be in series across the supply forming a half-bridge, with the primary of the main transformer between them and the midpoint of the two 220uF electrolytics. Somehow the TL494 has to drive the top and bottom of the half bridge.

Of the transformers, the bigger one (marked 'hanny 198') is likely to be the main one, and the smaller one next to it may be used for current sensing or base/gate drive of the main switching transistors, so its primary may be in an odd-looking place.

Where's C16 on the PCB? I can't seem anything on there that looks big enough to be a 2uF 250V capacitor.

There may also be two separate power supplies on this board, again like an ATX PC power supply, one being a small one delivering just standby power. That would explain the three transformers. The standby one may be a cheapo self-oscillating one-transistor affair. Perhaps that's what the CSN60 is doing?

Here's an example of a 200W ATX power supply which might bear some similarities to yours. Note the three transformers, one used for current sensing (I think) and base drive. From memory, I recall that some designs also rely on the base drive transformer to self-oscillate and start the whole thing up.

http://www.pavouk.org/hw/en_atxps.html

Last time I repaired one of these it was the standby supply that had failed. Its output smoothing electrolytic had dried up and caused the primary side switching transistor to fail. Replacing the transistor and electrolytic brought it, and the whole PC, back to life.

Chris
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Old 23rd Oct 2017, 12:46 pm   #28
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Default Re: What is a CSN60?

C16, which I'd removed before I took the photo, is in front of the heatsink on which T6 & T7 are mounted, and hidden by it. The circuit to which you kindly provided the link is indeed similar, C7 being the equivalent component there. As I noted in one of my posts the original 2uf capacitor only read about 5nf on one of those cheap Chinese testers, so I'll fit a new one, and check electrolytics, etc. Interestingly, the manufacturer's name is 'Foshan Hanyi Computer Device Co.Ltd.' so the PSU is, as you say akin to an ATX one. I suspect you're right about the 3rd transformer being the standby power, driven , or swirtched, by the CS1N60 mosfet. There is indeed provision for a wire link to allow for voltage doubling operation on 110-120v, as you say

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Old 23rd Oct 2017, 2:32 pm   #29
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Default Re: What is a CSN60?

Quote:
Originally Posted by 'LIVEWIRE?' View Post
C16, which I'd removed before I took the photo, is in front of the heatsink on which T6 & T7 are mounted, and hidden by it. The circuit to which you kindly provided the link is indeed similar, C7 being the equivalent component there. As I noted in one of my posts the original 2uf capacitor only read about 5nf on one of those cheap Chinese testers, so I'll fit a new one, and check electrolytics, etc.
Ah OK, that makes sense then. If C7 was so low in value then the whole thing wouldn't work properly.

Chris
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Old 23rd Oct 2017, 6:38 pm   #30
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Default Re: What is a CSN60?

I may have misquoted the reading I obtained from the 2uf capacitor - 5000nf approx, not 5nf! I didn't note the ESR &Vloss reading, but the cap, if I'm right, is about 5uf.
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Old 23rd Oct 2017, 7:23 pm   #31
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Default Re: What is a CSN60?

Quite often a cheap capacitor tester (or the capacitance range on an DMM) will think a leaky capacitor has a higher than expected value (basically, the capacitor takes longer to charge as the charge is leaking away).

I wonder if that's what is going on here.
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Old 23rd Oct 2017, 10:36 pm   #32
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Default Re: What is a CSN60?

That's what I thought, Tony. I'll replace the capacitor anyway. I have some 1uf 250v MP types, which will physically fit, but the only 2.2uf one I have is a 400v. cap., and is too large. How critical the value is I know not. Perhaps I'd better look for a 250v. 2u2 capacitor
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Old 24th Oct 2017, 6:52 pm   #33
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Default Re: What is a CSN60?

Today I carried out some further checks on the PSU board, and found that D1 ( a SB260) which is used as a half-wave rectifier to provide the +7v line at CN4 was short-circuit How did I miss that!! I also replaced the 680uf smoothing cap., which follows D1, which I replaced with a 1N4007, and fitted 2 x 1uf Mtealized Poly. Caps in parallel to replace C17. Next job is to test the PSU, which means I either have to supply a +ve potential to the base of a switching transistor seperately, or connect the unit back up to the amplifier module in order to test it. The circuit concerned is a simple linear one fed from the secondary of a small transformer marked 'hanny 93 EE16', the primary of which is driven by the CS1N60 which was the original subject of this thread. Two SB260s are used one to provide the +7v supply, the other the -7v .
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Old 24th Oct 2017, 10:46 pm   #34
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Default Re: What is a CSN60?

I've just checked the Data of the SB260 and it's a 2Amp Schottky Barrier Rectifier. (Should have guessed from the 'SB' prefix I suppose) Why would a Schottky Barrier rectifier be needed in a conventional Half-wave rectifier circuit? The 2 Amp rating I could possibly understand, since I have no data on the associated amplifier, and don't know what currents are drawn from the 7v supplies, although, from the small size of the transformer* supplying the AC, I would have expected the current drawn to be <1A, never mind up to 2A. (* No more than 1" square x 0.8" deep)
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Old 25th Oct 2017, 9:10 am   #35
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Default Re: What is a CSN60?

If these components are on the secondary side of the power supply, then they have to be Schottky diodes because they need to be fast. This power supply is running at tens of kilohertz, and a 1N4007 just won't do the job: it recovers much too slowly. You need to get a Schottky diode for this position. It doesn't have to be exactly the right one. Anything of adequate current and voltage rating will do the job. A scrap PC power supply is a good source of such components. The 1N4007 will not work, I guarantee you.

The rectifier circuit isn't just a half-wave rectifier. If it's the standby supply, it's probably a flyback converter. There's a useful explanation on Wikipedia here:

https://en.wikipedia.org/wiki/Flyback_converter

The magnetic field in the transformer is not a sine wave, and each cycle is divided into distinct parts during which the diodes, transistors and inductors play particular roles.

A transformer that size is perfectly capable of delivering 10-20W, so a couple of amps at 7V is no trouble. Because it's running at a high frequency, it's much smaller than a 50Hz mains transformer.

Chris
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Old 25th Oct 2017, 9:33 am   #36
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Default Re: What is a CSN60?

I've just read part of that explanation on Wikipedia, so now understand better how such a circuit works, Chris. The fact that the circuit runs at a high frequency did cross my mind, but only after I'd fitted the 1n4007. It hasn't been powered up since I replaced the shorted diode, so I'll look for a suitable Schottky rectifier diode, and fit that before I do so. Although I've been involved in Electronics repair for almost 50 years, I've spent most of that time repairing car radios and the like, so have never had much dealings with Schottky devices, and still don't fully understand them, I must admit.
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Old 3rd Nov 2017, 12:45 pm   #37
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Default Re: What is a CSN60?

Further progress(?) I have obtained, and fitted a 2A Schottky Diode, plus a replacement 680uf smoothing Capacitor, and have also fitted 2 x 1uf Metalized Poly. Capacitors in parallel to replace the suspect 2ufC7 in the Pavo circuit) in the primary circuit, but the PSU is still not working - no main DC, which I presume to be of the order of 50v, due to the use of 63v Smoothing caps. on this line. Anyway my attention turned to the two transistors driving the primary circuit of the transformer (equivalent to Q1 & Q2 in the Pavo Uk circuit). These are marked A13TA, but I can find no data on such devices (they may be 2SC13TA), but they must be similar to the 2SA4242 used in the PAVO PSU. These check OK'cold', so I'm wondering where the fault lies. Much as I hate to be beaten by things, this has been taking up so much time, that I may try and source a replacement PSU PCB, although from where I know not. I can find no data on 2SC13TA on the 'net either
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Old 3rd Nov 2017, 7:24 pm   #38
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Default Re: What is a CSN60?

In my experience, a transistor marked with A, B, C or D is likely to be a 2SA***, 2SB*** etc. type. However, if it is a little Philips beginning with a C, then probably a BC***.
There may be others, but I would start assuming a 2SA13**. Is it possible you misread the 3rd digit, ie 2SA13xA or event the third and fourth, 2SA13xx.
If 2SA two digits, likely to be pnp germanium, if 2SA3 or 4 digits, probably silicon, but still pnp.
Les.
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Old 3rd Nov 2017, 8:29 pm   #39
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Default Re: What is a CSN60?

Thanks for the info., Les. These are Silicon Power Transistors similar to the 2SC4242 ( I mistyped that as 2SA4242 in my earlier post) These are High Voltage NPN Silicon power transistors in To-66 (I think that's right) packages. The A13TA devices are the same type.
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Old 5th Nov 2017, 1:06 pm   #40
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Default Re: What is a CSN60?

Further checks on this PSU reveal that HT+ at 450v and 200v or so are present at the Smoothing Capacitors, and 200v is present at the Transformer primary, but the voltage present on the two A13TA power/switching transistors quickly decays to a very low figure. Unless this is due to the effect of a high frequency ciruit on my DMM, which I doubt, there is still a fault present, but at the moment I'm not sure what it is. The circuit is virtually identical to that of the PavoUK ATX PSU linked to in post #27 by cmjones01(Thank's, Chris)
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