Author Topic: Help needed to identify component in TDS460 power supply  (Read 3812 times)

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Online T3sl4co1l

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Re: Help needed to identify component in TDS460 power supply
« Reply #25 on: December 30, 2017, 10:59:06 pm »
Hmm, might work.  Worried about the longer switching time, and maybe the lower hFE (but hFE isn't too high on the MJW part, either, so maybe the circuit will deal with that just fine).

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Online capt bullshot

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Re: Help needed to identify component in TDS460 power supply
« Reply #26 on: December 31, 2017, 11:20:06 am »

I have a brand new S2000A which has quite similar characteristics as the BU508, but somewhat less  Amps than the  MJW16010A (8/15 vs 15/20   collector current ) . Do you think  I can  use it ?


I'd give it a try. The maximum Ic shouldn't be reached in such a circuit. If you can achive that some way, watch it for getting not too hot when running the scope.
Safety devices hinder evolution
 

Offline JacquesBBB

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Re: Help needed to identify component in TDS460 power supply
« Reply #27 on: December 31, 2017, 01:45:15 pm »
Thanks for the comments.

Finally, I have ordered the MD2310FX (14A/21A)
http://www.st.com/content/ccc/resource/technical/document/datasheet/5c/99/f7/04/f3/61/4b/37/CD00073553.pdf/files/CD00073553.pdf/jcr:content/translations/en.CD00073553.pdf

As  I wish also to reduce the noise of the scope, thus to reduce the heat dissipated by the power supply, and  regulate the fan accordingly. I hope that this transistor will dissipate less than the previous one.
 

Offline shakalnokturn

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Re: Help needed to identify component in TDS460 power supply
« Reply #28 on: December 31, 2017, 03:30:26 pm »
I've substituted the main primary transistor on the similar PS-1690 PSU with BU508AF and 2SD1887 without problems the BU508AF giving slightly better switching times.
Make sure you check the emitter resistor before powering-up again, failure to do so can lead to a lot of extra work.
 

Offline lihach

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Re: Help needed to identify component in TDS460 power supply
« Reply #29 on: January 02, 2018, 11:28:17 am »
Here I present the edited scheme of the power filter and the high-voltage part of the power unit
Be careful the circuit is drawn for yourself so there may be inaccuracies
« Last Edit: January 02, 2018, 11:31:53 am by lihach »
 
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Offline navales314

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Re: Help needed to identify component in TDS460 power supply
« Reply #30 on: January 02, 2018, 01:02:52 pm »
Oh no!, you didn't have the opportunity to read this;

https://www.eevblog.com/forum/repair/it's-not-always-the-capacitors-lecroy-lt342l-repair/msg1320619/#msg1320619


Likely now a few components;  fuse, varistor, main switching transistors + driver transistor, maybe the green module ETC...

The picture component is the Varistor [metal oxide varistor]. Try [130L10 from little fuse].
https://www.ebay.fr/itm/Lot-of-5-GE-130L10-130V-4-5KA-Metal-Oxide-Varistor-MOV-Radial-Leads-NOS/132252400791?hash=item1ecadb7c97:g:ancAAOSweW5U27pA

Edit: if I remember correctly, you don't need the varistor after the conversion.
Though I experienced this problem with the lecroy autorange circuit, I suspect your power supply is somewhat similar to it.

 |O

BTW, be careful the heatsinks are LIVE.

Regards;

Armadillo;
Help needed! My power supply didn't work it is two weeks ago i found it cracked ic cr18818 but i can't found at any store.have a similar of this?

Sent from my SM-J105B using Tapatalk

 

Offline Armadillo

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Re: Help needed to identify component in TDS460 power supply
« Reply #31 on: January 02, 2018, 02:05:33 pm »

Sent from my SM-J105B using Tapatalk

Relax. I suggest you create a new thread with detailed description of your problems and photos.
Many people can help you.
 

Offline navales314

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Re: Help needed to identify component in TDS460 power supply
« Reply #32 on: January 02, 2018, 02:24:36 pm »
Help needed
  My power supply didn't work it is two weeks ago i found it cracked ic CR18818 but i can't found any store have a similar of this or same pinout ic CR18818?   

Sent from my SM-J105B using Tapatalk

 

Offline JacquesBBB

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Re: Help needed to identify component in TDS460 power supply
« Reply #33 on: January 02, 2018, 02:38:26 pm »
Please use this thread only for matters related to the TDS460 power supply.
 

Offline JacquesBBB

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Re: Help needed to identify component in TDS460 power supply
« Reply #34 on: January 02, 2018, 02:48:35 pm »
Here I present the edited scheme of the power filter and the high-voltage part of the power unit
Be careful the circuit is drawn for yourself so there may be inaccuracies

Thanks a lot for the effort ! This is great work.
 

Offline JacquesBBB

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Re: Help needed to identify component in TDS460 power supply
« Reply #35 on: January 05, 2018, 10:48:51 pm »
I have now received  the components I ordered, and proceed to the remounting of the scope.
I replaced  all the electrolytic caps, except the 4700uF which I had not  received yet.
They were OK, anyway.

I put the MD2310FX. I had to drill an additional hole in the heatsink for that as it is slightly larger than the previous one.
I put a BY500-600 diode in series with the V150LA20BP.

Put the power on,
and everything is working again.

Thanks to all for the help, and in particular to lihach  for providing the right value of the varistor, and to capt bullshot  for telling me
about the potential problem of the MJW16010A transistor.
« Last Edit: January 05, 2018, 11:40:21 pm by JacquesBBB »
 

Online capt bullshot

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Re: Help needed to identify component in TDS460 power supply
« Reply #36 on: January 06, 2018, 10:36:57 am »
Congratulations, good job!
Safety devices hinder evolution
 


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