Voltage too high

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Voltage too high

Post by bill57 on Sun Jul 11, 2010 7:52 pm

Hello all...I have a Norelco model BX 640A/54 made in Holland. I just replaced the three 50/450 electrolytics and 3 tubes including the EM80 eye tube. I plugged it into a dim bulb tester with a 60w bulb. Radio played great up and down the dial on both AM and FM. Even picked up some on SW. Eye tube worked as it should. So I then plugged it directly into the house current of 120V and picked up very few stations. Eye tube stayed fully lit with no change between stations. I tried changing the voltage on the radio from 110V to 125V on the back of the radio but this caused a screeching noise so I put it back to 110V. So somehow I think it is drawing too much current and the dim bulb tester is making up for it. I did not change any other caps yet as I can't determine values and I haven't found a schematic.
So, any suggestions as to how I should proceed?

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Re: Voltage too high

Post by denver on Mon Jul 12, 2010 1:18 am

I would change all the caps , and check all the resisters.
Iwill check on a schematic for you . Be kind of hard to do without schematic. Ihave a few sites that might have one .
Give me a little time . Smile
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Re: Voltage too high

Post by denver on Mon Jul 12, 2010 6:33 pm

is this your set it is a bx640ahttp://www.radiomuseum.org/r/philips_bx640a.html
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Re: Voltage too high

Post by denver on Mon Jul 12, 2010 6:58 pm

hence philips norelco
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Re: Voltage too high

Post by bill57 on Mon Jul 12, 2010 9:08 pm

Yes that is my set. Unfortunately I am not a member so I cannot access the schematic. Thanks for finding this as I have not even found a picture of it. I have tried other sites such as Nostalgia Air and Just for radios but no luck.
I have taken a closer look at the black caps and have found values such as 1500pf, 2200pf, 8200pf, 41000pf. If I can convert these to US numbers I can go ahead and replace these. Tons of resistors. Don't see any that "look" suspicious but I have not checked any yet. Not sure where to start. There are also some alum metal cans that I assume are also capacitors. I also noticed that while plugged into the dim bulb tester(by the way the bulb is burning bright) most of the sound is coming thru the small speaker with very slight vibration in the larger speaker.

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Re: Voltage too high

Post by denver on Mon Jul 12, 2010 9:23 pm

here is a conversion chart http://www.justradios.com/uFnFpF.html You want figure anything out till you recap this set. Might be worth to join radio museum for the schematic .
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Re: Voltage too high

Post by denver on Mon Jul 12, 2010 9:26 pm

I will do more searching for a schematic . When i get more free time. Smile
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Re: Voltage too high

Post by bill57 on Mon Jul 12, 2010 9:48 pm

Thanks Denver, That will help a lot. I did not see that on their site. I will try recapping and see how it does.

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Re: Voltage too high

Post by denver on Mon Jul 12, 2010 9:55 pm

Are you sure your set is 110 volts . Most sets in europe were 220 volts . Just wondering.
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Re: Voltage too high

Post by denver on Mon Jul 12, 2010 9:58 pm

www.radiomuseum.org here is the site.
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Re: Voltage too high

Post by bill57 on Tue Jul 13, 2010 8:12 am

This radio has 3 settings on the back. It has a small black dial you pull out to change to 110, 125, or 220. It was set at 110 when I got it. I tried it at 125 but that made it worse so I left it at 110. So at least I'm sure that it is set at 110v. Maybe something is messed up in that switch. I'll check into that if changing caps don't help. I believe this radio was made for use in the US because it goes to 108 on the FM scale. Something I read somewhere that if the FM scale did not go to 108 it was not intended for our market. Be nice if there was more english on the parts.

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Re: Voltage too high

Post by Bill Cahill on Tue Jul 13, 2010 11:45 am

First, it makes sense. At higher voltage the leaky caps are worsenning, so radio plays worse..
Second.. On the caps. Those are in english. They are marked in Picofarads, or, in old layman's terms, micro-microfarads.
Hope this helps.
Bill Cahill

Some of them will need to be replaced by mica caps.

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Re: Voltage too high

Post by bill57 on Tue Jul 13, 2010 6:43 pm

Thanks Bill, yes it helps me understand some of these better. So for instance I am replacing a 1200pf with a .001uf, a 2200pf with a .0022uf, a 41000pf with a .04uf. Am I correct so far? However three have me stumped with these markings: 2K7P X.4, 1KP 0.4, 6K8P X.4
May be english but greek to me.These look exactly like the others but that is the only markings on them. Any help on these??

I also have two small alum cans about an inch long that are marked 10uf with a plus sign on one end so I'm going to replace them with electrolytics. I do plan on doing a couple at a time and then put power to it and see how it does.

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Re: Voltage too high

Post by Bill Cahill on Tue Jul 13, 2010 9:16 pm

Correct so far. I don't understand the last two. Are they larger than others? Physically, I mean.
Those to 10 uf are electrolytics. Be sure you put correct voltage ones in.
Try the known values first.
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Re: Voltage too high

Post by denver on Tue Jul 13, 2010 9:51 pm

I think that they are resistors, Philips had a bad habit of just printing part numbers on caps and resistors. We need to find you a schematic. But Philips resistors .were know to stay in tolarance for many years.
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Re: Voltage too high

Post by bill57 on Tue Jul 13, 2010 10:06 pm

I have replaced all of the caps that show actual pf values and it has made a difference. The dim bulb tester is not as bright but still too bright. I now have 5 left that have the weird numbers on them. They are physically the same size as all the others. About 3/8" diameter and 3/4" long and solid black. I have not changed the two lytics yet. Voltages are marked so I will be sure to use the correct ones. There are two of the black caps with 6K8P x.4 on them so I thought maybe I will take one loose and see if I can get a value on it. I have a meter from Harbor Freight that does measure capacitors. Maybe I can compare the reading to a new capacitor and figure out the value and try one and see what it does.

It would be really weird, Denver, if these are resistors since they look just like all the caps that had values on them. Maybe I'll leave them alone for now and just change those two lytics I found and see how that does. Thanks for all the help. It has been a learning experience.

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Re: Voltage too high

Post by denver on Tue Jul 13, 2010 10:45 pm

Philips did use cathode resistors. Part cap part resistor.
And they were black. Look up cathode resistor. Very Happy
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Re: Voltage too high

Post by denver on Wed Jul 14, 2010 9:53 am

Found a service manual free if you joinwww.radiotechniek.nl lots of philips and other manuals.
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Re: Voltage too high

Post by bill57 on Wed Jul 14, 2010 8:24 pm

Thank you for finding this Denver. Very clear documentation even if it is in German. The schematic and top & bottom views are very clear. I will study it along with the part numbers. Should be very helpful to anyone else reading this to download schematics. Very easy to register also. And its free!

Thanks again...will post any results on this.

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Re: Voltage too high

Post by denver on Wed Jul 14, 2010 9:37 pm

There is a link i seen somewhere. On the site translate to English . Thanks sure took me some research to find this.
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Re: Voltage too high

Post by Alfred Corbin on Wed Jul 14, 2010 10:08 pm

It does appear that line voltage is too high for the set or for some components; however something you said does not ring true:

You said it's worse when you go to 125 volts on the line voltage selector. When you do that, it actually gives the set less voltage than when it is set at 110 volts. Did I misunderstand?

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Re: Voltage too high

Post by bill57 on Thu Jul 15, 2010 12:21 am

Actually, Mr. Corbin, It was worse sounding when I switched it to 125v. It created a low pitch squeal regardless of any station it was on. This was before I had changed any caps. I have a few more to go then I will try it again at 125v and see if its any better. It seems to improve the more caps I change out. I did not know that changing to 125 actually lowered it. Thanks.

To Denver: Yes I have also seen something on translating to English. I'll look for it later. It really doesn't impair reading the schematic too much though. The part numbers are there with values which is really helping me figure out whats what. I'm not the greatest at reading the schematic but the diagram showing the components in their place really helps me locate everything.

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Re: Voltage too high

Post by bill57 on Fri Jul 16, 2010 11:00 pm

Finally completed replacing all capacitors. Still pretty much where I started. Plays great as long as it is plugged into a dim bulb tester with a 60w bulb. Bulb is dimmer but still on. Dimmer still when I set the radio to 125v. But plug it directly into wall outlet and as radio warms up a loud squeal starts and continually gets louder along with the station reception. And for some reason I lost reception on FM. Before I started FM played fine. I've only checked a couple resistors so I quess thats my next step. So what would the wattage be on a resistor over an inch long? 5 watts maybe? Could a tube cause this situation. I've tested them on a simple emissions tester and 3 of them where practically dead. I replaced those 3 but could the rectifier be allowing too much voltage to pass thru?

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Re: Voltage too high

Post by Bill Cahill on Sat Jul 17, 2010 12:19 am

I doubt the rectifier.
You have to be neat in wiring, and, as close ot original as possible.
Hope you didn't use any disc capacitors.
Did you replace electrolytics?
Bill Cahill

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Re: Voltage too high

Post by denver on Sat Jul 17, 2010 2:00 pm

Iam with bill on this . Sounds like the electrolytics to me .
You do have polarity right. And close to the original values.
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