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Blue Robbie power issue
Old 4th April 2020
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Blue Robbie power issue

Hi. Im having a power issue with my BLUE Robbie. Let me preface this by saying that I am not very knowledgeable on the subject, but had someone look at it that was. I was told that the issue is what appears to be a thermistor right at the input inside the PSU, and was most likely used to limit large currents at turn on, but he was unsure and uve been unable to find schematics on thr PSU. The markings on the thermistor (or whatever it is) are P250 145 CF on one side, and P250 RPC6 on the other. Pictures below.

Does anyone know what this is, and if so what I can replace it with? Or can I safely remove it? Any help is much appreciated. Thanks!
Attached Thumbnails
Blue Robbie power issue-20200404_113304_hdr.jpg   Blue Robbie power issue-20200404_113248_hdr.jpg   Blue Robbie power issue-20200404_113551.jpg  
Old 7th April 2020

I have a Robbie and I'v got the schematics but I haven't got the original power supply. When I bout it it came with a non original power supply.

It's late here so i'll have a look at it tomorrow and see what it could be.
If it's a Termistor it is to avoid over-power when you turn it on.
Don't you find an equivalent termistor ?
Old 8th April 2020
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Thanks for the reply and taking a look at the pics. Apprefiate it.

I havent found the same thermistor, if thats what it is. Ive tried searching online for all of the markings on it, but havent been able to find anything and without the schematics, not sure what i can replace it with....
Old 10th April 2020
Hi Andy,

I'v been looking in my Robbie and my files. I hace the schematics but only the preamp, not the power part of it.
As I told you I don't have the original power supply (10v and 54v AC) and on my power supply there are only the 2 transformer, the fuse (2,5A, 230v) and nothing else. So if you don't find the varistor (I thing it should be a varistor) it should not be an issue; I don't have it an no problems. The only problem could may be if your fuse break.

Could you send me a picture of your power supply please ?

Good luck !
Old 14th April 2020
I have an dubt.
How is this Thermistor -or whatever it is- connected to the circuit ? I can't see it on the pictures.
In serie or parallel ?
Old 16th April 2020
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Hi Gae, I'm sorry for not responding sooner! i didn't get a notification on your previous reply.

The thermistor (?) is soldered right at the input of the " figure of eight" mains power socket (across its two terminals). In fact it is the only other component in the power supply unit except the transformer. It is hard wired in series with the mains.

A couple more pics here -

You mentioned you have an aftermarket power supply? Do you know what I might be able to use? I'm happy to buy something to replace it, but Blue wanted $180...

Many, many thanks for your help!
Old 16th April 2020
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Same pics from the links posted above....
Attached Thumbnails
Blue Robbie power issue-20200416_105706_hdr.jpg   Blue Robbie power issue-20200416_105651.jpg  
Old 17th April 2020
Hi Andy,

If it's in serie I'm 90% sure it's a thermistor.
If the temperature is getting to high it increase it's resistance.
I would eliminate it without danger, in fact it's probably there to protect the transformer.
If you want to be 100% safe get in touch with a electronic components shop and ask for a new thermistor giving the max power and the voltage (You have 110v, no ?)
Here in Europe we have 230v and I'd need a 2,5A intensity.
What is strange to me is that there is a thermistor but no fuse ...

Good luck.
Old 18th April 2020
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Thanks you! Will just try to bypass it.

One more question if you dont mind. It is a 110v psu. Though i moved to the UK a couple years ago. You mentioned you had an aftermarket psu? Any advice on what i might be able to buy? If I can get a power supply that will work on 230 instead of having to use a step um converter, would rather just do that anyway...

Again, thanks for your help!
Old 19th April 2020
Well you'd need to make your own box, I don't think there is some think like that on the market: you need a 54v + 10v transformer. It'a quite easy.
I see in the original one it's just one toroidal transformer with 2 secundary (I don'y know the right name in english) 54v + 10v. It will be easier if you get 2 different transformers:
one for 54v, 0,45VA x 2 (My transformer is toroidal and has 2 outputs, each 55v 0,45A linked together) and an other one, normal, for 10VA ( again: mine has 2 outputs, each 5v, linked)
Don't ferget to add a fuse: T2,5A (on 230v)
I'v made some pictures but I don't know how to upload them ...

Good luck.
Old 4th August 2020
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If I'm not mistaken, that device is a polyswitch, PTC or PPTC self-resetting fuse. I could not find a device with those identical markings or that manufacturer logo and there are variations between manufacturers and even between series of same manufacturer as to what those numbers mean. It would appear to be 250volt, 145ma (.145A) OR more likely a 1.45 Ih hold amp rating. About the most common convention I could see was the voltage rating on top and the lower number divided by 100 ( x.010) as the hold current rating in amps.
I just repaired one for a friend of mine with a broken IEC320-C8 power inlet connector ( Switchcraft RAPC322X fits perfectly with no modification to the housing, I also could not source the original connector)
120VAC primary current draw is about 150ma with full output signal. At first I thought fuse was 145ma as I had seen a few similar markings, but that would be marginal (trip current is around 300ma, so might work), but maybe it is a 1.45amp device. For 220V version, current draw would be around 75ma (.075A)
The other markings are probably a manufacturing code.
The transformer should have a thermal fuse embedded in the windings.
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