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Unidentified part on PCB

G

grahamdocman

pfm Member
Hi guys,

I'm not quite sure where to post this on PFM, so if I've got it wrong apologies in advance. I know I'm really flying kites and you are my last hope. It is DIY electronics, but not HiFi.

I have a hot tub which has stopped working, the offending part is shown in the attached linked pictures, it's the one below the cotton wool bud.

From what I've managed to work out: It seems to be a link between the topside key board panel and the relays to the various pumps. I've checked all the relays and they are fine, the signals from the topside key panel (which too is working fine) just are not getting through.

On the PC board it has "U7" against it, and pre cleaning off the thick sprayed on plastic /clear ? silicone covering over it, it was a little charred on the top (needless to say none of the pumps in the hot tub are working).

I've cleaned it off as best I can, but due top the damage I can't decide or identify what it is. It might even be a simple bridge making contact between the various traces on the PCB.

Anyway, at over £500 for a replacement board, if anyone can help identify this part I'd be very grateful.

I have contacted GECKO (who distribute the boards) but they can't help me, I can't find any circuit diagrams anywhere on a thorough 'net search.

Links to pictures (they should blow up quite large to enable one ot see the partial part number)

https://www.dropbox.com/s/2a2q9twozgk4534/D71_2510.JPG?dl=0
https://www.dropbox.com/s/dp0wbm7wa619hkp/D71_2506.JPG?dl=0

EDIT - links should now work (see below)
Thanks in advance the hope someone can help,
Graham
 
Last edited:
My best guess from what I can read of it, the described function and number of pins is SN75468. If pins 10- 16 go to loads which then go to a + voltage then that just about clinches it. It could be this or any one of a load of other potential faults! If it's what looks like prob a microcontroller then it's game over.
 
Arkless Electronics said:
My best guess from what I can read of it, the described function and number of pins is SN75468. If pins 10- 16 go to loads which then go to a + voltage then that just about clinches it. It could be this or any one of a load of other potential faults! If it's what looks like prob a microcontroller then it's game over.
Click to expand...


Thanks for this.
I think you have nailed it for me. I also checked on the datasheet and its the exact same size as my current one. Also the role you describe for it is spot on : it seems to control the relays which then control the pumps for my tub.

I'll give it a go, it's definitely worth investing and "gambling" a few hours and a few pounds if it saves me over £500.

I'm definitely not up to designing my own low level board ! but attempting to replace a part is within my reach and I'll enjoy the trying.

I'll keep you posted.
 
After all your shared help I'm about to buy the relevant part. In fact I'll get a couple just in case I need a spare or mess up the soldering.

BUT can anyone tell me the difference between: SN75468-DR, SN75468-D and SN75468-NSR ?
Does it make any difference ?

I've looked at the data sheet, but it doesn't seem to help.

Thanks. The one I have removed is surface mounted, not "through the hole"
 
D and DR are the same but DR is supplied on a reel or part of a reel

NSR is a different package, probably larger, still surface mount but you need to check the dimensions on the relevant data sheets.
 
One thing to note is that your board is conformally coated, presumably because it is a less than ideal environment. This should be cleaned off locally and replaced once you've put the new part on (wonder if a small heatsink would help if it's failed through heating?).
A decent silicone sealant would be fine, best to avoid the vinegar smelling ones if possible.
 
grahamdocman said:
Thanks for this.
I think you have nailed it for me. I also checked on the datasheet and its the exact same size as my current one. Also the role you describe for it is spot on : it seems to control the relays which then control the pumps for my tub.

I'll give it a go, it's definitely worth investing and "gambling" a few hours and a few pounds if it saves me over £500.

I'm definitely not up to designing my own low level board ! but attempting to replace a part is within my reach and I'll enjoy the trying.

I'll keep you posted.
Click to expand...

All with the same number of pins will be the same size.... The best check is do the pins connect as the data sheet suggests?
 
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