My Hitachi CP1421R smoked

[Foneet1]

Earlier today i got an NTSC compatible VCR and as i was watching a tape, there was a loud "snap" from the TV and it went black (and probably turned off but i couldn't tell) with smoke from the top. I quickly unplugged it and opened my windows.

Inside i found this piece (pic 1) and the thing that, i assume, it has been a part of (pic 2). Everything else seems to be fine.

So, what do i do? Is it done for or do i just have to replace that part? What even is it, and is it possible to get a replacement?

edit: I looked in the service manual and it says that it was "IC POWER" and looking up online does give me options to buy it, so that question is closed

[agardiner]

Although such an IC blowing up was a fairly common problem, there was almost always a reason. Given the age of the set, I would be suspicious of capacitors in the power supply, but also check all of the secondary diodes to see if one has shorted.

If not, then I would change all of the capacitors in the power supply and then replace the IC. Also, I would suggest purchasing the IC from a reputable source such as Cricklewood, as there are fakes around which can lead you a merry dance.

[Sideband]

As you were asking what the item was that had blown, it seems that you have little or no experience of circuits or components. Nothing wrong with that but please let us know what knowledge you have so that we can pitch the answer at the right level. Power supplies can be the devil in some TV's and as stated, these things usually blow like that for a reason and it's unlikely just to be the IC that's gone faulty. Capacitors will be the first check followed by diodes but also dry joints (poor solder joints) could be a problem. The advice to buy a replacement IC from a reputable supplier is also very valid. As you are in Spain, we can't suggest good suppliers but avoid eBay unless you know the supplier. Don't be tempted to just replace the IC without doing other checks. If you have little or no experience of power supply repairs, it would be better to seek the advice of someone who does.

[Foneet1]

Originally Posted by agardiner

Given the age of the set, I would be suspicious of capacitors in the power supply, but also check all of the secondary diodes to see if one has shorted.

So i need to check everything in the power supply area? To see if the caps are working and nothing is shorted, right?

[simpsons]

Hi Foneet1

Following on from Sideband's point, do you have a modern multimeter? Are you familiar with testing diodes and or resistors and capacitors, soldering and unsoldering components?

Would you be able to follow a circuit diagram?

All these skills can be learned but before you delve into the cause of the fault you will need to practice some of them.

This Hitachi uses European designed and manufactured parts which is a great help but, I would just now hold back on checking or changing any components.

The STR S5707 was a popular device and so hopefully members familiar with the circuit will be able to point you in the right direction.

Chris

[Foneet1]

Originally Posted by simpsons

Hi Foneet1

Following on from Sideband's point, do you have a modern multimeter? Are you familiar with testing diodes and or resistors and capacitors, soldering and unsoldering components?

Would you be able to follow a circuit diagram?

Yeah, I have a multimeter and some basic soldering skills. Testing components and following diagrams not so much.

[Foneet1]

Taking a closer look, this resistor does not look ok.

[Foneet1]

And it's connected to pin 5 of the IC that blew up, which is "Over current protection". I'm not sure what happened here, but my dad (who has some electronics experience, not enough to help me though) thinks that the resistor combusted due to age and took the IC with him. I think that IC blew up due to something else and sent extra power to the resistor.

Any help is appreciated

[Lloyd 1985]

I think you are right, resistors don’t just burn up like that without a reason, something else downstream of it caused it, it could just be the IC that caused it, but then something else must have caused the IC to go pop like that. As others have said, check all the electrolytic caps in the power supply, and also any diodes.

Regards
Lloyd

[Welsh Anorak]

Check ther main HT smoothing electrolytic too (I speak from recent experience...).
It'll be something like 100uF, 400v.

[Foneet1]

I desoldered all the caps in the power supply area, the IC and the burned resistor. My multimeter doesn't have capacitance settings so i did the voltage testing, charging it with a 9V battery and testing the voltage. Marked with a check are those who have the same or similar value to the battery, and they are going back in the circuit, everything else gets replaced.

I also discovered a crack in C806 and it is connected to the IC, on the pin 1, probably it is the culprit.

[Welsh Anorak]

Very likely that's the cause.

[ben]

Those blue disc ceramic caps are notorious, had them fail in psu ccts many times.

[Foneet1]

Originally Posted by ben

Those blue disc ceramic caps are notorious, had them fail in psu ccts many times.

Should i get the same one or something better?

[Maarten]

Same capacity, higher voltage will usually do the trick.

[Foneet1]

So, I need: one 1W 100 Ohm resistor, two 4700pF 500V caps, one 470pF 2KV cap, one 1000pF 50V cap and a STRS5707 IC.

I found everything on Cricklewood Electronics, except the resistor which i found on Amazon. Do you guys know a single place where i can get all of that?

[Michael Maurice]

The wattage doesn’t matter as long as its not lower than the one you’re replacing.

Use this or this

[agardiner]

Good luck with the repair and let us know how it goes!

[lightning]

l've had mixed success repairing these PSU's when the top has blown off the SMPS lC

For most TV sets second hand PCB's are available on Ebay or from somewhere like EMOS electronics.
However this looks like it might be an old CRT TV so you'll likely have to try and repair it.

[Maarten]

Originally Posted by Foneet1

So, I need: one 1W 100 Ohm resistor, two 4700pF 500V caps, one 470pF 2KV cap, one 1000pF 50V cap and a STRS5707 IC.

I found everything on Cricklewood Electronics, except the resistor which i found on Amazon. Do you guys know a single place where i can get all of that?

I think you only need the 470p 2kV (originally 1kV I assume), the resistor and the IC.

4700p 500V sounds as if originally 4700p 250V AC Y2 class types were fitted? Those should be left alone generally, except when faulty (if the set fails a PAT test, for example). If you want to replace them anyway, use 275V AC Y2 rated caps. They don't exist in 500V version.