Philips 141U. New member - peterb396.

[Peterb396]

Hi guy's, just joined and after many decades of working I am looking to the facinating field of vintage radio.
My first purchase from a antique/house clearence shop is a Phillips 141U radio which caught my eye.
The unit appeared to be in a decent condition so for £15 bought it,
Arrival home the case although grubby was in good nick. On stripdown the rear panel had a small piece broken off the corner and one of the base cover screws were missing.
After carefull removal of panels etc the chassis was out of the casing on my workbench, very grubby but looked intact & no sign of interference from outside bodies, until now
The fact that the mains plug was missing stated that there will be a fault so I proceded with caution, (live chassis high power caps etc).
After examining the unit, I gently eased out the valves, (hard to do with one hand in your pocket) and proceded to do a basic cean up of the chassis.
All looked fine so plucked up the courage fitted a mains plug and through a protected circuit I decided bang or success.
Nothing......then idea, valves need to warm up....minutes later noise from the speaker. Twiddled the controls, volume/on off, tuner eventually got audio & music which didn't sound bad at all; all the time using my senses.
Now the bad part, after about 10 mins of dancing round the room...
Phuuff, the unit died....on inspection...wait for it...blown capacitor, (black tar) . I'd pre-cursered the internet and managed to download a circuit from another site and guessed it to be C32 which had blown.
Further reading on your threads had lead me in the direction of the need to replace this cap & all other black caps. My problem is due to my initial comment I have a limited supply of this type of component so my question is are they all electrolytic type or standard paper and where can I obtain a replacement set of them, or if any of you guy's can supply me with a set, (cash & postage uk) that would be fantastic. I can then start to take readings & see if there are any other faults. In the mean time I'll concentrate on the cabinet and continue reading up on past and future posts
Regards peterb

[Station X]

Hello and welcome to the forums.

C32 is the mains filter capacitor. Snip it out and the set should work without it. Replace with a Class X capacitor.

Lots of info on replacing caps etc. here:-

https://www.vintage-radio.com/repair...ion/index.html

[paulsherwin]

You can replace the other old Philips 'black pitch' caps with any modern plastic film type of adequate ratings. Just buy on price if you don't mind what they look like.

Lots of possible suppliers here: https://www.vintage-radio.net/forum/...ad.php?t=55701

You don't need to work with one hand in your pocket if the radio is unplugged from the mains! (Be very careful when it is plugged in though.)

[Station X]

I suggest you don't use this radio again until you've replaced C29 (Manufacturer's sheet) the audio coupling capacitor. If it's electrically leaky it could cause irreparable harm to the set.

[paulsherwin]

Yes, search the forum for 'That Capacitor' for lots of discussion of this notorious component, which is found in the majority of 1950s valve radios regardless of manufacturer.

[Peterb396]

Cheers for the info Paul, will venture to the site. Am looking forward to this and future vintage radios.
(hands in pocket was a bit tongue in cheek) but the large cap on the chassis would give concern, still hold charge with power removed

Hi Graham thanks for the info, the radio is stored away until I can get the caps..I'm assuming C29 is the cap buried beneath C37 but I intend replacing the lot. I'm not too interested in the monetary selling side so ugly looking caps aren't an issue for me.
I have an isollater for the ring circuit in my wkshop, sometimes I forget to turn it off so looking forward to having this baby playing and a reminder for me to isolate before I leave.

[ms660]

Not to mention C30.

Lawrence.

[rambo1152]

Welcome Peter, I like your narrative style and hope you'll be a regular poster here.

A missing mains plug does not necessary mean the item is faulty, some dealers intentionally remove the plug or the entire mains lead in the belief it turns the radio into an ornament and absolves them of certain responsibilities, it's all a bit of a legal minefield.

Don't worry about the mains filter cap going thermonuclear, it often happens, and it means you are probably the first person to power it on for decades, that's a Good Thing. It probably will have blown the plug fuse and done no other damage.

[Peterb396]

Cheers Rambo..very cautious, early stages; old adage "if it's in there it's there for a reason" so will await new caps.
In the mean time I need to assess my workshop; woodworking, dust, shavings don't mix well with electro/mechanics so a solid seperation will be required, have space..ish so a project before a project!!
I have some background....don't we all though😁
Regards
Peterb

[DonaldStott]

Hi Peter and another warm welcome to the Forum.

I restored one of these Philips 141U sets a couple of years ago so here is a link to that Thread some of which may be helpful:-

https://www.vintage-radio.net/forum/...d.php?t=169575

Easy to work on and has the standard range of valves for that period, but in quite a small case, so nothing too challenging or esoteric!

The set is attractive when illuminated but does have a tendency to run very hot!

[Peterb396]

Ah..that's one of the 1st posts I read Donald before posting mine, gave lots of info reading the threads, yours sounded worse than mine to repair, so hoping for a good result with new parts, will need a new lamp before I can see it glow.
Regards peterb

[Peterb396]

Further to my previous 1st post I am experiencing some issues after replacing the Phillips Black Caps as follows:-
a) Audio has deteriorated.
b) Wispy smoke from V4
c) V4 & V5 very hot
I will attach files at the end of this thread.
All the Chassis caps have been replaced along with C30 (Transformer suppression) as per values except
C20 which I tried a 1uf motor run & an Orange dip Axial.
C34 correct capacitance but only 630v
C37 correct capacitance but 400v
These three caps are only short term & short power up time for testing.
The audio has deteriorated from my 1st power up pre C32 blow out. (Note C29 C30, C32, had significant damage all the others appeared fine, (face value, not measured them yet)) but were changed anyway be it because they were black or had to be removed to get to the others. The valves were removed and all pins fine emeried (is that a word?) the volume control pot flashed with cleaner and general checking of done to date. Note I did inadvertently drop V5 from about a foot (in old money) onto a cloth covered bench would this be a cause for my following problems.
So to the point after powering up, Hum and buzzing volume control set halfway before audio above the buzzing appeared there was very little station pick up which was distorted, after a minute a faint wisp of smoke rose above V5, I immediately switched off and de-powered the set. V4 & V5 were v hot to touch.
Having read ‘Howards’ encounter with issues regarding the volume control and V5 (UY41) & V4 (UL41) problems I decide to check out the resistance of all the chassis resistors a copy of which is attached, some are out of tolerance but not Howards issues.
I am awaiting upgraded Caps
I will change the faulty Resistors but wondered if the ones slightly out of tolerance would be fine, there is some oxidisation on quite a few of the resistors which when cleaned off may improve readings. I have also ordered a NEW set of Valves.
This leads to another point:- the price of this gear now a days, I was expecting packs of 5 or 10 of individual caps but got 1, I know they are struggling with chips for new cars but 70+year old vintage radios….come on
I have some knowledge but know very little re:- radio Valves!
Anyway enjoy the pics/vid
Regards
Peterb396
ps guy's can't send the video of smoking, filesize too big even compressed & zipped it's only 10 sec but can't get it to 4.00meg, I could send to an email as it's only 14meg?

[Station X]

It appears you're using the R&TVS service sheet which may use different component designations when compared with the manufacturer's service sheet.

Just a few comments.

Valves do not smoke! Could it be that grease or dust on the envelope is burning off?

You replaced C20 (screen grids to chassis) 0.1uF with 1uF which is ten times the required value 0.47uF is closer, but still half the required value.

As mentioned earlier C29 and C30 should be replaced.

The voltage across R17 will tell you whether it's drawing excess current. It should measure 8.2 VDC.

There should be close to zero volts DC on V4 control grid.

[Silicon]

The thermistor will get very hot.

[ms660]

C34 and C3 can be regarded as safety critical components, fit Y2 Class types.

Ref. your resistance measurements of R8 and R20, make sure you've interpreted the readings correctly, if so then check the values again with them out of circuit.

Measuring R20 in circuit when switched to MW will give a very low reading, approx. 10.5 Ohms according to the service info.

Lawrence.

[Peterb396]

Thanks for the replies Guy's I've since downloaded the service sheets via Paul's site and compared the component values; they are identical so wasn't far out. The only difference was that the Test Report I also downloaded (British Radio & Television 1954) shows C31 as 4700pf (0.0047uf) which according to the other service sheets is incorrect (2200pf (0.0022uf) so I will ignore that. I couldn't do a check with the original Black cap as it was unreadable. The article however has a good schematic of replacing/rewinding the drive cord if ever needed.
The data sheet I attached with the Resistance comparisons also had the capacitors I had changed including C29 & C30 but were ringed in yellow which were hard to see so apologies for that.
Mrs B is working so I'm allowed in the workshop later today armed with new components including a full set of valves but FIRSTLY will recheck my readings and take out of spec resistors out of circuit to check, (good shout Lawrence with R20 didn't check which wave I was on prior).
Because of my tribulations with black cap blowout then smoking valve and heat, (just cleaning fluid/dirt, (thank you Graham)) I didn't have time to take powered up readings not wanting my first project blowing up but feel more confident now after getting to know the unit and all your comments has put me at ease.

[paulsherwin]

A lot of the capacitor values aren't critical and they may have been changed during the production run.

[Peterb396]

Originally Posted by paulsherwin

A lot of the capacitor values aren't critical and they may have been changed during the production run.

yes Paul Good info, the article is dated June 1954 so could be close to 1st production run

[Peterb396]

Hi Guy's just a quick update on Philips 141U.
All Black Caps have now been changed for correct value/ratings/X&Y as recommended along with resistors that were out of tollerance.
Unit working fine, (safe), just needs adjustments for audio quality.
Reading post/threads, some are mentioning voltage readings etc from service manuals, I downloaded the relevant service sheets from Paul Stennings site which has the valve readings but they don't have any data or reference points, is there an additional service manual others are using, I was wondering if more information is on the DvD's or USB?

Whilst awaiting parts I constructed the Lamp Limiter from the design and it works a treat, all the parts I had to hand and built it around an oldold science lab mains box, I upped the mains with an old electric iron cable terminated with an RCD, made it portable so can be used anywhere. I had a MK double socket (dpole) so I can use a mag lamp or soldering iron.
I also built a stand to accept any of this type of radio so you can mount the chassis and work on all parts without the restriction from a work bench and possible damage to components, switches, bulbs, pointers etc

[Station X]

Originally Posted by Peterb396

Reading post/threads, some are mentioning voltage readings etc from service manuals, I downloaded the relevant service sheets from Paul Stenning's site which has the valve readings but they don't have any data or reference points, is there an additional service manual others are using, I was wondering if more information is on the DVD's or USB?

Where valve sets are concerned voltage readings are almost invariably measured with respect to chassis unless otherwise stated.