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Old 14th Aug 2019, 1:16 pm   #1
cdm1christopher
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Default Philips 170A restoration

Hi all
Just acquired this little beauty for 25 quid more or less immaculate had a few replacement parts including a new 3 pin mains input. My only concern there is that the earth strap is connected to the body of the mains tranny. Is this safe?
Also any pointers on replacing the 0.047uf capacitors. Is it worth using PIO or standard 630v polys?
I'm also replacing the electrolytic caps whilst in there.
The output transformer also needs rewiring as the attached wiring is crumbling leaving lots of exposed wire. Are the windings on these soldered straight to the tranny? As opposed to being one continuous length of cable? Only ask as if rewiring I don't want to remove solder only then having to re solder. Although I could re sleeve the wire. Just came to me.

To be fair it works fine bit of crackling and slight hum but think Pots just need cleaning. Picking up stations from all over the world ****** amazing really since I'm only using the foil plate on back plate at present. No external aerial as of yet.

Any info always welcome.

Cheers Chris
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Old 14th Aug 2019, 3:48 pm   #2
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Default Re: Philips 170A restoration

Hi Chris, I am just finishing off restoration of a Mullard MAS 281/15 that has an identical chassis to the Philips 170A. These are fine sets - very sensitive and sound good. If you don't have it already then I recommend you get a copy of the Trader Sheet #770. You can get one here https://www.service-data.com/product...12/5017/t14812 . You can also get the Philips manufacturer's data sheet but component numbering will be different so my references will be to the Trader. I have attached the mains lead earth wire to a tag on one of the mains transformer chassis mounting bolts which is fine because there is good continuity to chassis. If yours is connected to one of the other transformer bolts then at least check it for continuity using a multimeter on the ohms range from the mains plug earth prong to the receiver's chassis. There should be about one Ohm or less resistance. The transformer is at least partly coated in black pitch so there's at least a possibility that you will otherwise get a bad joint. The screw type electrolytics on these sets rarely survive so you're wise to replace them. There is plenty of room underneath the chassis to solder in smaller modern replacements but do disconnect the old ones first. I also replaced the following capacitors that were all leaky: C36 (0.001uF), C34 (0.047uF), C37 (0.001uF), C30 (0.047uF), C29 (25uF electrolytic - at least 25v wkg voltage needed), C24 (0.047uF), C13 (0.047uF), C13 (0.047uF), C11 (0.047uF), C4 (0.047uF). You don't need to replace the cathode decoupling capacitors C27, C18 or C5 because this will have no beneficial effect. You can use whatever types of capacitor you want as long as they are new and rated at least 400v; 630v is better. I prefer to use the yellow polys. Definitely replace the crumbled wiring - it can be lethal and if short circuits develop that can cause fire or trash the transformers. I can't really see the point of resleeving. I replaced all of the mains transformer wires one at a time using new neoprene insulated wire. As others have said this looks better than PVC which has too bright colours for the period look. The wires are soldered directly to the transformer but I didn't have any trouble replacing them. I've posted 3 pics below. Good luck, cheers, Jerry
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Old 14th Aug 2019, 8:43 pm   #3
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Default Re: Philips 170A restoration

There seem to be a lot of these sets about. Just completed mine. Excellent sets with an RF amplifier that greatly enhances the sensitivity.
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Old 24th Aug 2019, 3:39 pm   #4
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Default Re: Philips 170A restoration

Thanks for reply guys.
Replaced the electrolytics just put some 33uf rifa caps in the original cans always bit messy. These caps are actually very well made.

Well wiring absolutely right I seem to be constantly changing a wire only to find the next 5 have all split exposing bare wire. Seems to be mainly on top part of chassis going to trannys and some valve bases underneath. Happily surprised that the transformers don't have flying leads direct from the unit which is a bonus.
Only thing did notice is that one of the tuner cans on top of chasis has had its wax removed and on cleaning moved it around a bit hopefully not caused any probs there so melted some wax and recovered it.

The EF39s interesting someone has painstakingly used some fuse wire and wrapped around the valve base then soldered to the original conducting wire I'll post some pics. Is it worth keeping these as they are the originals or just replace?

The other thing I was thinking is the EBL31 is it worth removing the IO1 base and just replacing with an SC8 base so I can use the EBL1 since seems to be a few of these around or just buy one of those Philips EBL31 valves which look to me to be EBL1s converted to an EBL31 as they are taller.

The other thing I noticed is the AZ31 not sure if what I have actually is as I managed to pick up a mullard one in mint condition for 9 quid and the top where mica cap is does not have those suspended wires which I think go to the anodes I think!

Someone has obviously done some restoration be it very little maybe just to keep it up and running although I think fire hazard would have been waiting to happen.

Okay the earth strap is fine all tested but all wires have been removed from that side of the tranny apart from the mains in. The voltage regulator has been removed although I would have preferred that to still be an option if required.

I'll post some pics.

Cheers Chris
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Old 24th Aug 2019, 4:49 pm   #5
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Default Re: Philips 170A restoration

Quote, cdm1christopher: "The voltage regulator has been removed".

I owned one of these sets many, many years ago. My memory may be playing tricks, but I don't recall a voltage regulator as being fitted.

Al.
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Old 24th Aug 2019, 6:49 pm   #6
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Default Re: Philips 170A restoration

I'm sure it had a voltage tap circular shape to the right of the Mains transformer looking from the rear. Unless it was for something else.
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Old 24th Aug 2019, 6:53 pm   #7
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Default Re: Philips 170A restoration

Couple of pics quite happy with wiring.
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Old 24th Aug 2019, 7:36 pm   #8
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Default Re: Philips 170A restoration

Hi Chris, I think the term "voltage regulator" brings to mind semiconductor electronic devices but I know what you mean - the mains voltage selector immediately behind the transformer. Removing it is fine so long as you are certain you've got the mains IEC connector wired to the appropriate windings for your local mains voltage (via the on-off switch). The 245v winding is the safest to begin with and then check the valve heater voltage is at or close to 6.3v. If low then try the 220v tap. If running the set out of the case then do watch where you're putting your fingers because the exposed contacts on the mains switch are conveniently placed to give you a nasty shock or kill you. Nearly all red-coated EF39s suffer from flaked metallizing or bad connections to the earth wire at the base rim, made worse every time you wiggle the valve to remove it. The RF amplifier won't care about this but the IF valve will likely go into oscillation if the shielding screen is compromised. Winding wire around is an old trick that usually works providing there is enough metallized paint left on the valve. If it works OK then leave it. As far as the output valve is concerned I guess it depends how much you want to spend. There certainly do seem to be very few EBL31s around at the moment. It might be worth putting a wants request here - you never know. As your 170A isn't in mint original condition there is no harm in changing the output valve holder if you want to. The EBL1 will of course work fine. You might want to give Mike Lewis a ring on 01582 580367. He might be able to help you with the voltage selector and the EBL31. Cheers, Jerry P.S. I thought you said the radio was working so not sure why you want to replace the EBL31?

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Old 24th Aug 2019, 9:41 pm   #9
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Default Re: Philips 170A restoration

Thanks for info Jerry.
Yeah it works fine I'm just one of those people that like to fiddle to be honest.
The case is in mint condition I'll post a picture of that plus still has original back cover with the Ali plate aswell as the Ali sheet on base of case. Speaker still has original cotton cover and sound is well for a radio speaker exceptionally good and the front cloth is in mint condition.
The bulb holders I don't think are original and as you can see from the pictures the mains input has been modified and grounded. Hence the tap has been removed and the on/off volume connected straight to the transformer. All the wiring done is correct I got it from a guy who just had it on display and used now and again and he got it from some old guy who cherished it and made the modifications.
Obviously all original wiring has perished but even so it still run perfectly. But of course has all been renewed using 600v 22awg lapp kabel wire.

Not sure if it's worth reverting the mains input back to it's original state. Although as a fiddler it did cross my mind ha.

I'll sit on that one for now. I'll fire her up tomorrow now all wiring is done I replaced a few caps and some of the resistors where out of spec.

I just hope that tuning cap I moved has not messed it up.

Cheers Chris
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Old 24th Aug 2019, 9:58 pm   #10
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Question Re: Philips 170A restoration

Quote:
Originally Posted by cathoderay57 View Post
I think the term "voltage regulator" brings to mind semiconductor electronic devices but I know what you mean - the mains voltage selector immediately behind the transformer.
A 'voltage regulator' can be based on semiconductors, valves or even things like saturable reactors, e.g. magnetic amplifiers. But I fail see how a mains input selector switch can be regarded as a 'voltage regulator'.
Perhaps I have something to learn here.

That IEC mains voltage input connector is a modification, of course, but IMHO, it's a worthwhile improvement over the original connector.

Al.
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Last edited by Skywave; 24th Aug 2019 at 10:07 pm.
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Old 24th Aug 2019, 10:15 pm   #11
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Default Re: Philips 170A restoration

So called ‘EBL31s’ sold by UK valve dealers for > £25 or more are invariably converted EBL1s with an octal valve base fitted over the side contact base. A giveaway is that the converted EBL1s still have their 3/8” top caps fitted whereas the EBL31 is 1/4”. The fitting of the octal base makes the valve too tall to be used in Ecko A22s but if height isn’t a problem the converted valves work fine as electrically, and the size of the ‘bottle’, the EBL31 is identical to the EBL1.

Generally, NOS EBL1 valves - though not commonplace - aren’t as rare as EBL31s. As I have an Ekco A22 and my (adult) son has two, only the correct height EBL31 will so. Hence, I’ve converted several EBL1s to EBL31s by removal of most of the side contact base, fitting a reduced height octal base and changing the 3/8” top cap for a 1/4” top cap. It’s a bit of a ticklish task but wholly successful with care.

This thread gives full details of what’s involved:

https://www.vintage-radio.net/forum/...ighlight=EBL31

Hope that’s of help to someone.
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Old 25th Aug 2019, 10:51 am   #12
cdm1christopher
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Default Re: Philips 170A restoration

Thanks for input guys.
Al nothing new to learn here what I said is grammatically incorrect "voltage regulator" I made it sound like it has say a variac fitted to it. On the rear of the unit right next to the transformer from the Limited pictures I've been able to find shows some sort of dial circular in shape with wires from the transformer linked direct to this maybe a dial with wipers on it where you select mains input voltage going into the unit in other words a tap.

I hope this has cleared up your confusion as to what I originally said?

I think I'm lucky as it has all the original valves which as previously stated work fine the EM34 is a bit dull but I've put that down to the resistors being out of spec. What was interesting is on spec sheet they are 820k resistors but on mullard valve sheet they are 1meg. So I've whacked two of them in instead. Hopefully that should brighten it up. Could be wrong.

I might have a go at converting one of these EBF1s seems to be a good challenge.
Any ideas on how to re glue a top cap on a valve as one of mine is a bit loose. I think super glue will melt I do have metal epoxy resin but don't think that will connect to the glass. I do have some wax but I think it will end up looking like a candle ha.

Anyone got a spec sheet with voltages on it? The one I have does not the trader sheet.

Just think which always amazes me this radio is 73 years old and still works.

Cheers Chris
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Old 25th Aug 2019, 11:40 am   #13
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Default Re: Philips 170A restoration

Quote:
Originally Posted by cdm1christopher View Post
Anyone got a spec sheet with voltages on it? The one I have does not the trader sheet.
If you mean the voltage tappings on the mains transformer my guess would be 110, 125, 145, 200, 220, 245 VAC.

Valve voltages are given on the Trader sheet 770.

Lawrence.
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Old 25th Aug 2019, 12:43 pm   #14
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Arrow Re: Philips 170A restoration

Quote:
Originally Posted by cdm1christopher View Post
Al: nothing new to learn here. What I said is grammatically incorrect: "voltage regulator" - I made it sound like it has, say, a variac fitted to it.
Now I'm more confused. There was nothing wrong with your grammar. To me, it didn't sound like you had a Variac connected at all. Besides, a Variac isn't, and doesn't have the properties of, a voltage regulator.

Anyway, this line of discussion is obviously of no help to you at all, so I shan't pursue it: good luck with this radio.

Al.
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Last edited by Skywave; 25th Aug 2019 at 12:57 pm. Reason: Amend last sentence: needed a re-write for clarification.
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Old 25th Aug 2019, 12:53 pm   #15
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Quote:
Originally Posted by cdm1christopher View Post
Just think which always amazes me this radio is 73 years old and still works.
Chris
When I was a very young child, there was one of these in the house: it was the main source of entertainment, news, etc.; there wasn't a T.V. It was my father's pride and joy. It was that very set which awoke my interest in all things 'radio'.
73 years old and still works, you say. So it's a bit older than I am. But for me, although only a few things 'work', those that do, hurt like hell!

Al.
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Last edited by Skywave; 25th Aug 2019 at 12:58 pm. Reason: Grammar!
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Old 25th Aug 2019, 1:17 pm   #16
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Default Re: Philips 170A restoration

Al you've lost me again a variac can regulate AC voltage I'm sure of that. Unless your talking about something completely different!

Well your doing well age wise and Radios are a new thing to me so I'm still trying to understand how it all works as from a reception point of view how to build a good quality aerial which has numerous possibilities depending on frequencies how all the different valves work in unison including the linking of resistors and capacitors as well as those attached to the tuning frequencies which alot of people say leave alone otherwise you'll need to retune it which is another specialist area all of it's own. That's what stirred up my interest.

Wish I could say I'll be around at 73 I'll be lucky to last the next 3 maybe 5 years at 54.

And yes it hurts like hell at times this end. But all this fiddling with valve pre amps amplifiers and radios etc keeps me going. By the way I'm not an electrical engineer hence I will get things wrong and have had a few shocks as well.

Thanks for info will get the 770 spec sheet.

Cheers Chris
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Old 25th Aug 2019, 1:48 pm   #17
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Default Re: Philips 170A restoration

Chris, a regulator maintains the value of something. In electronics that normally means maintaining a particular voltage, but an oven thermostat on a gas cooker is also a regulator, and the term is used more loosely in other fields such as steam engines. A variac doesn't regulate anything - it is a variable ratio transformer which can be used to step up or step down an AC voltage. You are confusing 'regulator' with 'selector' or 'adjuster'.

Enough of this nit picking though - back on topic please.
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Old 25th Aug 2019, 2:12 pm   #18
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Default Re: Philips 170A restoration

Here ya go some pics of case. I think it's in pretty good condition.

Cheers Chris
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Old 25th Aug 2019, 2:14 pm   #19
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Default Re: Philips 170A restoration

Not as clear as I'd like I'll try again later.
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Old 25th Aug 2019, 6:29 pm   #20
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Default Re: Philips 170A restoration

It's up to you what you do to your own radio but why change the EBL31 if the set is working OK? The EBL1 is electrically the same so can be fitted with an Octal base but why go to all that trouble (and have to change the top-cap as well) if the existing EBL31 is OK?. The EF39's do commonly lose their out screening and I usually just wrap some tinfoil around them rather than fitting a new valve. OK it doesn't look very professional but they are hidden from sight when the set is in use. Valves are a finite source and I don't change them for new ones unless it's absolutely necessary.
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