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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 10th Oct 2017, 6:08 pm   #1
'LIVEWIRE?'
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Default Dr Dre Beatbox problems

This is a 3-terminal To-92 device in the Power Supply circuit of a Dr. Dre Beatbox. At first I thought it was partiall s;c because I measured about 10 ohms each way between what I took to be the base & emitter terminals. When desoldering said item, I noted that it is marked 'T8' on the PCB, whereas other transistors are designated 'Q1' or whatever. Could it be a Thyristor maybe? Betweeen what i took to be the base & collector terminals I read ca. 500 ohms using the Diode test function on my DMM, with the positive probe on the 'base', but O/C the other way round. Oddly enough the low resistance I mentioned above is still present with T8 removed, and, from what little of the cicuit I traced, I cannot see from where this comes. Incidentally the Beatbox won't power up, and I've established that none of the DC voltages are present, so there is nothing for the 'power on' button to detect/switch.
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Old 10th Oct 2017, 8:55 pm   #2
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Default Re: What is a CSN60?

It's not one of those dual diode packs is it? Common anode/cathode arrangement (centre-pin).
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Old 10th Oct 2017, 10:14 pm   #3
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Default Re: What is a CSN60?

It could be. I've tried to find data on it by Googling 'CSN60', but have drawn a blank. Maybe i misread the type no. even through a magnifying glass. If it is a dual diode then one diode is o/c. Looking at the bit of circuit i traced out a dual diode (or two indiviual diodes correctly connected) would make sense. The pin which reads o/c to the other two is connected via a 510 ohm resistor to a SMD I.C. so could be the supply to it, particularly as there is an electrolytic capacitor from the junction of the 510 ohm R/IC pin to earth. The low resistance across the two outer pins of the device would than also make sense as it would be a transformer winding. The only puzzling thing, though, is the 2 ohm resistor (R19) from the outer pin of T8(the CSN60) to earth. Perhaps it does resolve to a conventional full wave rectifier circuit. The PSU is made by Foshan Hanyi Computer Device Co.Ltd., but I don't see an identicl one on their website. Maybe the people who import Dr.Dre equipment in the UK stock the PSU?

Last edited by 'LIVEWIRE?'; 10th Oct 2017 at 10:26 pm. Reason: To add further info.
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Old 11th Oct 2017, 10:04 am   #4
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Default Re: What is a CSN60?

Straight Outta err... Christchurch

https://www.kondor.co.uk/contact

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Old 11th Oct 2017, 10:54 am   #5
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Default Re: What is a CSN60?

Thanks for the link, Andrew. They don't list the Beatbox, but I may phone them to find out. For some reason their on-line contact form doesn't respond to any attempts to enter details on it.
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Old 11th Oct 2017, 12:59 pm   #6
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Default Re: What is a CSN60?

A generic 600V n-channel mosfet, by any chance?
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Old 11th Oct 2017, 1:28 pm   #7
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Default Re: What is a CSN60?

There is a CS2N60, seems to be a MOSFET and can be found on eBay from China (eventually!).
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Old 11th Oct 2017, 2:10 pm   #8
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Default Re: What is a CSN60?

The CS2N60 is a high power (54W) device, and not a TO-92 package, but there are plenty of other xxxN60 TO92 600V Vds n-channel mosfets. This Alibaba page: https://www.alibaba.com/trade/search...t=G&viewtype=G shows some of them, including the CS1N60.
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Old 11th Oct 2017, 2:35 pm   #9
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Default Re: What is a CSN60?

As it happens I bought some Chinese 2N60s recently, and while the package is bigger than TO92 it's still very small - I was surprised. They are 2A 600V devices. Let me know if you want me to take some measurements.
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Old 11th Oct 2017, 6:06 pm   #10
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Default Re: What is a CSN60?

It seems as if the device may be a CS1N60, which is a TO92 package mosfet rated at 1A, so the original may be OK after all, and my attempt at explaininig things in post #3 is wrong. The two pins across which I get a resistance reading are presumably the Source & Drain, with thother pin being the gate, though why this should be grounded via a 2 ohm resistor beats me.
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Old 11th Oct 2017, 8:37 pm   #11
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Default Re: What is a CSN60?

If the CS1N60 is employed as the primary side switch in the power supply, it's likely to have the drain (middle pin, almost always) connected to one end of the transformer primary, the source to a low-value resistor to the 0V rail (used for current sensing by the switch-mode controller) and the gate to the controller chip (if there is one - might be discrete components) possibly via a resistor.

An N-channel MOSFET will look like a diode with its anode at the source and cathode at the drain. The gate should appear open-circuit to the other two pins, though of course the surrounding circuitry will have an effect. If source-to-drain shows a low resistance in both directions, that worries me - then I'd be looking for short-circuit primary smoothing capacitor or rectifier.

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Old 11th Oct 2017, 8:48 pm   #12
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Default Re: What is a CSN60?

Spot on, Chris. I looked again at my notes - the only difference is that it's the LH pin 9as viewed from the bottom of the device) which is grounded via a 2 ohm resistor. The centre pin is connected to the transformer primary, and th e RH pin to a SMD IC via a 10 ohm resistor. I'll check the data sheet of the CS1N60 to confirm things, but, from the above, the LH pin is the source, centre pin the drain and RH pin the gate. If I'm right, the readings I obtained in post #1 are between Gate & Drain, which may indicate an internal diode conneceted between gate & Drain, but for what purpose? A diode connected across the Tx primary I could understand as it would protect the FET against the effects of back EMF. Paul, if you could take some measurements with a "N60 and post them here it might be helpful. Thanks in advance.
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Old 11th Oct 2017, 9:09 pm   #13
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Default Re: What is a CSN60?

There is an internal diode, but not on the gate. See http://www.alldatasheet.com/datashee.../UTC/2N60.html

I measured 5k between drain and source in one direction and o/c in the other. There was o/c between the gate and other connections with both polarities. That was with my Black Star 3225MP and other meters may give different values depending on the voltage used.
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Old 11th Oct 2017, 9:15 pm   #14
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Default Re: What is a CSN60?

The diode is intrinsic to the structure of the mosfet. It’s not something that’s added as an extra feature, although it does eliminate the need for an extra protection diode in things like dc to dc converters. They are also known as body diodes.
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Old 11th Oct 2017, 9:16 pm   #15
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Default Re: What is a CSN60?

Thanks, Paul. Your readings and mine are similar, but I made an error in post #12. The internal diode is connected between source & drain. I have to admit, despite over 45 years working with electronics, I'm not sure what the function of the internal diode is. Somewhere I have a book about FETs which i bought many years ago. No doubt there's an explanation in there. The low resitance I measured across the source-gate was with the FET removed, so that needs investigating.
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Old 11th Oct 2017, 9:21 pm   #16
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Default Re: What is a CSN60?

Your post mentioned using the diode test function of your meter. That shows the voltage drop, not the resistance.
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Old 11th Oct 2017, 9:25 pm   #17
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Default Re: What is a CSN60?

Quote:
Originally Posted by 'LIVEWIRE?' View Post
Thanks, Paul. Your readings and mine are similar, but I made an error in post #12. The internal diode is connected between source & drain. I have to admit, despite over 45 years working with electronics, I'm not sure what the function of the internal diode is. Somewhere I have a book about FETs which i bought many years ago. No doubt there's an explanation in there. The low resitance I measured across the source-gate was with the FET removed, so that needs investigating.
This article explains the body diode: https://www.digikey.com/en/articles/...inside-mosfets
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Old 11th Oct 2017, 10:04 pm   #18
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Default Re: What is a CSN60?

The function of the internal body diode is virtually nothing. As diodes go it's too slow for the frequencies the MOSFET is normally used for and care has to be taken to ensure the diode never gets turned on. It's there as something implicit in the way MOSFETs are formed in a silicon substrate. We'd rather it wasn't there but we're stuck with it.

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Old 12th Oct 2017, 7:58 am   #19
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Default Re: What is a CSN60?

Paul, thanks for that reminder. I may also have checked the FET with my DMM on a normal resistance range. AG & David. Your replies, and that Digikey page answered my question. Thanks also for that info. I'm 99% certain the FET is OK and the fault is elsewhere, though I'm not inclined to trace out the full circuit of the PSU. Gone are the days, it seems when such info. was available from manufacturers or importers of equipment, more's the pity!
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Old 12th Oct 2017, 8:41 am   #20
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Default Re: What is a CSN60?

I'm glad to hear its starting to make sense. The resistance/diode test readings on the MOSFET sound like they're OK. Does the PSU have a controller chip? If you can identify a part number on it, or post a photo of the whole thing here so someone else can identify it, usually looking up the data sheet for the chip will reveal the circuit for the PSU almost exactly.

I can remember looking at the service manuals for 1970s-era Philips TV sets and discovering that many of the circuits were pretty much identical to the examples in the data sheets for the Mullard chips they used. The same frequently applies today, though the chips aren't made by Mullard any more...

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