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LC TDK PSU issues


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2 minutes ago, marmotta said:

Thanks for the link, but I think the best solution is to see another tdk 699-0153.... 

Well, if you can get a replacement PSU of the same type for little money, go ahead! If not, it's worth trying to fix the existing one as I did with my old Astec PSU (still working after been fixed). BTW, a quick ebay search reveals a used TDK 699-0153 for 79,95 € + shipping from Germany to Italy. I bet the fix is cheaper...

 

Another attractive option is to attach a modern PSU with compatible voltages and wattage...

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1 hour ago, techknight said:

The more a stare at it, the more it looks like a dual diode. maybe a clamping network. 

I agree. That PS is similar to the Sony PS in my HD20 SC I recently worked on.

Here's an image of the corresponding components in the Sony PS. Also apparently unmarked.

 

dualdiode.jpg

Edited by MOS8_030
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2 minutes ago, MOS8_030 said:

I agree. That PS has very much the same layout & design as the Sony PS in my HD20 SC I recently worked on.

Here's an image of the corresponding components in the Sony PS. Also apparently unmarked.

 

dualdiode.jpg

On the pcb is marked as diode... you can shot a photo of the entire pcb?

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  • 1 year later...
On 4/23/2018 at 2:00 PM, marmotta said:

Solved! Is a thyristor ;-) 

 

31189756_10213411285851290_1067602941344

Hi, I have this same PSU and I think this component is bad. When I turn it on, it clicks (indicating overcurrent, it runs for 9ms and stays off for 95ms). The -5V line seems good (charges and discharges with the pulses). The +5 and +12 lines though, have the same waveform on an oscilloscope: A flat line with slightly higher voltage on the pulses (600mV-off time, 800mV-on time). This suggests that the overcurrent is happening in one of these lines.

As this component gets quite hot, I am identifying it as the culprit. But I have a few questions:

What's a thyristor doing in a PSU?

Were you successful in replacing it?

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