McMichael 135.

[Herald1360]

Just looking at the cap restuffing pictures- please ignore this if I'm preaching to the converted- but the replacement modern type does look extremely small physically to have the same voltage rating as the original. Depending on where they are in the circuit, at least some of the original capacitors would need to have been rated to stand the full HT voltage for the set.

The pictures don't show if the originals have a voltage rating on their labels, if so it must be a bit further round than the views given.

Chris

[therave]

looks like you are right dam mail order all are only 50v so there going to come back out thanks pointing this out will have to get the phone book out and find someone that stocks them

[ChrisBU]

You might find these caps are suitable. http://uk.farnell.com/jsp/search/res...Redirect=false

[therave]

Day 5,,, Thanks to chris i averted disaster at that point i had restuffed 5 caps only had 4 to go never mind i will do them again a simple mistake just coz i could not see the small print on the caps. After i finish this restore i am going to put 250vdc accross them 50v caps just for the fun of it and to see what could have happend to my radio. Anyway ive got the caps on order for 10.00am from RS so i hope i will still be on time with this project, Also had to order in 10's and 20's so when i finish this the ones i dont use will be for sale. So for the rest of today i decided to clean the lw/am switch this was the start of a bad idea after geting the 6 nuts off the thing just started to fall apart 5 of the contacts just fell off so have made new ones with some 10 thou brass i had in the shed well it works so all is ok now. The wife asked a q why are you doing all that cleaning when you are just going to put it back in the case (but we know why don't we). Next time we will have to get a group of 5-10 and have a go at 24 hour restore on a beer can,,lol. This is like the first time someone used a bulb will it work or not i think it will,, my only worry is the field coils on the speakers there not oc so you never know. if any one wants to call around for the power up on friday just pm me. The if cans have not had paint just a clean... Heres where i am now just did not think i would have got this far. Look at that tuneing cap then look at the first post ---

[therave]

just to let you know chris the only print on them is this

145-c
1ųf
139-c
0.1ųf
142-c
0.002ųf

i am just going to use 250vdc caps i think that will be ok

thanks for saveing me from scrap

[mark pirate]

i am just going to use 250vdc caps i think that will be ok

I used 400v rated caps in mine, 250v is a little underrated.
They are quite cheap, and will easily fit within the old tubes.

Mark

[Herald1360]

Pleased to be of service

I'm impressed by the results so far

Chris

[therave]

well day 6 two part post all caps now replaced with new ones 400vdc not 250vdc got lots left. thats RS for you

speaker time i never found out what them caps where there for but i can tell you that thay are electrolytic 8ʯf at 500v wax i think its some kind of crosover but if you know tell me dont keep me it the dark.. let checked the speakers first was the 5" ligthly pressed the cone only to find it was stuck solid so striped and found rust on it removed this and all was ok with first one ,,next one the 8" was not stuck but had lost it's seal so striped and repaired. how to repare cones and fix to frame remove all rust i used pva if you are doing this dont use fast glue try the glue on a bit of paper first it has to stay flexible when set you can repaire rips in the cones just use soft glue and 200gm paper. The funny thing is the 8" has two field coils i dont know why but some one will tell me i hope?

almost time to put the power on

[therave]

last cone pic

[Oldtimer74]

Re reforming the caps. Sorry I have not replied before but I have been away.
I know that the idea opf running the set up on a variac is often proposed but I do not agree with it for two reasons. Firstly using a variac automatically reduces ALL voltages in the set. This includes the rectifier heater so it does not heat up properly and may not therefore produce adequate HT voltage or indeed any at all depending on how far down you wind the Variac. Equally, or more important, it is essential to measure the leakage current and see how it drops over time. All you need is a separate DC supply of about 250 volts, (Of course if you are reforming a lower working voltage capacitor then you must use a lower voltage supply), a 10k resistor and a milliammeter (preferably a multimeter so you can change the range as the thing progresses). The resistor and milliammeter are connected in series with the 250 Volt supply and applied across the electrolytic (having first disconnected the electrolytic from any circuitry). The current will start quite high but should drop rapidly and continue to do so until only about 1 mA is flowing. The capacitor may then be considered OK. If the minimum is much more after even an hour then throw it away as it will eventually heat up in use and explode. And boy do they make a mess!!
Remember to discharge the capacitor afterwards or you might get an unpleasant surprise!!

Pat G3IKR

[therave]

well its still day 6 at 9.00pm---- Time to put the power on with a 100w light bulb in line as advised and we have no smoke power on lt and ht, 55v on feild coils all valves light up thats a good sine! up to now all ok. 20 seconds later a hum on the speaker and thats it thats all i get if you change bands it does make click sounds but thats it and thats as far as i can go my knowhow is at a end------- so now i need HELP---- lots of it if i want to finsh this i have just 24 hours. so all IDEAS plez. or will it not work with the bulb in line mind you it must!! let me know HELP

[therave]

still day 6 removed the bulb and-----------we have radio 4 but with a loud and i meen loud buzz i now think them caps on the feild coils where there for some thing come on where are all the late night guys/gals this must be easy now

[therave]

well i know what the prob is the 442bu has just died it melted so has any one got one in manchester?

[therave]

well thats it u14 died i just used a normal spaker on on it and there is still mains hum may need sum caps here and there to get rid of the hum. No way am I going to pay £18.00 for a valve. If someone can send me the data for the valve I may be able to find a modern way around it. got the meter out 750v 5.0v-lt and only one feed to the feild coils at 55v i must be reading this data wrong...well up to now even if the set has no sound i know that the tuner is ok we did have radio 4 also one or two up and down the lw and some funny noise (hum) but i think this has something to with the caps that where on the speakers.. well that looks like it.

night night guys/gals

[mark pirate]

If you have a lot of hum, re-stuff the smoothing electrolitic.
You can check this first by replacing them under the chassis, leaving the old one disconnected, then try the set again, this could've sent the rectifier on its way, so replace the cap before fitting a new one.

Mark

[Geoff 555]

Hello, jolly well done, it's looking great. The 8 X 8 mf condensor's by the speakers are the smoothers and on mine are 500V. I couldn't see them in the picture, attached by a alloy bracket in between the speakers.
Good luck.
Cheers.
Geoff.

[therave]

hi here's a pic of them, i persume these are across the feild coils

[BassoonBloke]

Hi There,

Just in case you hadn't realised the 2 smoothing caps on this radio go at either side of the speaker field coil. The field coil it's self is used as a choke in the radio's power supply, set up as a C,L,C filter. This being the case i'm not suprised that you had massive hum when you ran up the radio without them being installed . The HT supply will probably be quite high so stick with 450/500V electrolytic capacitors.
The radio looks really nice. Good luck with the rest of the restoration.

Alan.

[therave]

day 7 well we gave it a good go,,, sat down and looked over the service data i feel like a right one now could i not have seen it but at lest we know that it is all ok even though i need two caps and one rect tube i say we have finished wiyh time to spare once i get the parts i need i will do a post but i still am not going to pay £18 a tube

thanks to all that have helped me

[Top Cap]

Hi, I hope someone can help you with a replacement rectifier, you have done such sterling work so far. I know somewhere I had an R2 Brimar rectifier but goodness knows where it is, have been through most cupboards. It is not quite the same having an indirectly heated cathode but the same characteristics as the 442BU. Hopefully someone has one closer to hand.
Keep up the good work!
Les