Hello everyone, it is good to find an Australian radio site.
I am after a circuit diagram of a 64-52 Little Nipper.
It needs new power supply capacitors and I also like to replace the coupling capacitors at the same time. This really improves picture quality on T.V. sets.
It has a dual 16μF which I bridged with a 47μF (all I had at the time at this voltage) but I have read here that this could overload the rectifier.What are your thoughts on 22μF? The 16μF are quite expensive

Merry Christmas everyone.

Hi and welcome.

Dunno about the "-52" bit, but I do have notes and schematic for the model 64 with valve line-up: 6BE6, 6BA6, 6AV6, 6M5, 6X4.

Does that match yours?

Clarify which valves are in it, most of the latter ones are similar. 47μF is liable to strip the cathodes on the rectifier.

If you want better filtering I tend to use the Spragues. These are a physically bigger cap, but tend to have a better ripple rejection, and I suspect higher current rating. I have had cheap 450V type fail in two years.

22μF is OK; with a heater rectifier, you will get away with 350 to450V. 5Y3, 500V Replace all electrolytics and paper caps. Mica cap failures are not uncommon in them (normally on HT around the 6AV6 if it's one of them).

Yours sounds like it is working? Some of these have a "black coated" Audio transformer which have an attrition rate worse than Krieslers.

Do not forget resistors. 10M on 6AV6 often goes high and someone (accounts?) changed the screen resistor from 2 x22K to a 10K 1Watt. As there is more than 10mA going through it, it slowly burns. Use 2Watt (Evatco) or 2 x22K

100K's fail regularly and if it's around 1956 (anything) be prepared to replace every resistor.

Marc

G'day Little Nipper,

Can you please visit your profile page at your earliest convenience and be a little more specific with your location? Your current settings breaks a function on the forums and whilst this isn't critical it does slow things down a little.

As Marc suggested, it is okay to go a little higher with the capacitors that filter out the mains hum. I do this a fair bit mainly due to the fact that many radios already have capacitors at that value. The critical issue is making sure the working voltage doesn't go below what was originally specified or the capacitor will explode once the power is connected, showering the underside of the chassis with scrolls of foil and oily paper.

HMV and a few others often used transformers that were dipped in pitch to stop them vibrating whereas most others were dipped in varnish then baked. Pitch doesn't radiate heat as well as other coatings and when these transformers get overloaded for whatever reason this leads to their higher failure rate.

GTC, Yes that valve lineup matches mine. I see your Email is hidden, how will I Email you?

Marcc,
The Sprague's are $15 each, filter capacitors are less than $2. I need 2 of them so the Sprague's will be worth as much as the set. If 22μF won't hurt the rectifier I will use a couple of those. (I have inserted these into a bolt on can in T.V. sets before) Low ESR caps are the best filters but I am worried about the inrush through the valve rectifier. Solid State televisions seem to love these low resistance capacitors. 6X4 is the rectifier.
I bought it from a second hand shop, "sometimes it worked and sometimes it did not". One of the valves was cracked off at the base. I guess when the night air got 'thin' enough it worked.
Now it is not very loud but I always fix power supply problems before delving any deeper. I prefer to replace only the parts that need replacing but I can see your Idea of replacing everything to make it reliable.
The Transformers have a silver band holding them together but the insulation looks dark, nearly black. Do you mean an entirely black transformer from being dipped?

Brad,
Didn't your mother tell you 'never ever ever put personal details on the internet?
This transformer looks like it has varnish on it.
In transistor sets I am comfortable with doubling the the filter capacitor values, though I rarely go this big.

Please have a very merry Australian Christmas.

Unhide your email address and I'll send you what I have.

Assuming it's the correct schematic, then it shows those PS caps as 16μF 350 volt peak.

Forum member Steve Savell has 16μF / 450 volt for $2.25ea

You can contact him here:

http://www.goznet.com/contact.html

That is one of the later fifties ones by the sound of it and the bad audio transformer is one that has been dipped, with little runoff. Not the power tranny.

Never seen one yet (touch wood) with a dead PT, some of the Philips PT's, did have a bad habit of having wires from the winding, exit out the side. 123L I have is one of them.

Paper caps & old electroytics, I can assure you are not parts to leave in there. It is virtually mandatory replacement, with them.

Old unused electrolytics "dry out" or loose their "form" (polarity) & will often explode or present as a short circuit..

Most paper caps leak like sieves. This leakage will impinge on the bias & overall well being of the next tube, if it couples plate to grid. Most valves do not like positive grids.

I have seen one in the last few weeks where the 6M5 & rectifier sockets were damaged, one had flashed over and niether were of a good quality, or design. Ceramics were better there, as they are the hottest running valves.

Marc

Little Nipper,

Showing a location is a requirement for membership and is required of all members, as stated on the registration form. It does not have to be your street address (and nor should it be) however to be fair to other members, showing the state you live in and, at the very least, the nearest large town to where you are shouldn't be a problem as this does not identify you. I would appreciate you correcting this information by the end of the week so I do not have to undertake this task myself.

GTC,
Yes, those are the PS capacitors I have in this set.

Marcc,
The output transformer is silver also but it looks like some black oozing out of it, which drips down from the PI filter and on to the alignment diagram. I wondered where this came from. The transformer only has one screw holding it down and the other end is up in the air about 5/16". Is this from factory?
What would happen if I rewaxed the capacitors or even dipped them in marine varnish?

Where can I find more about history and models of the Little Nipper series?

Brad,
I am not in a 'Right State' anymore, I have put the correct one.

Thanks for the replies everyone.

If the caps are paper type some of the Americans love taking the inards out & putting new caps inside the paper cover.

I have done that on a 1929 Lyric to maintain apperance, the rest were in a plug in can (you can get a way with murder in there, as they are unseen ... but need to be safe).

The inside of paper caps is the issue, they dry out and that kills any hope of self healing so they punch through. Some had an oil in them, which contains PCB's (Poly carbonyl Bi-Phenols .... nasty stuff) Beware!

We might need photos here. post to Brad so we can see what we have, my email is not hidden.

If the speaker transformer is in a tin can, it's an ISO. They had pitch in them which migrates with heat. It is not original, which is why it has one bolt. It is physically bigger. If its one of them

If you bolt it to a flat surface it will cut the wires off & short unless there is a strategic hole. 62-52 has the OP transformer inside the pan. Some of the latter ones had a ferrite antenna. The one I have in service is not one of them.

Due to cost, if it is an ISO & OK raise it from the chassis using washers. It would hang with the pitch facing the chassis.

There are several variants of this series and I have serviced quite a few of them. The plastics are really common.

HRSA may have something on them? I just fix them

Marcc

Yes, those are the PS capacitors I have in this set.

If you still want the schematic and alignment notes, temporarily unhide your email address in your profile so that I can email them to you.

Little Nipper, I appreciate your co-operation.

There's a few purists here in Australia that like to fit modern caps inside the originals. In the case of receivers from the 1920s the same applies to other components such as the resistors that were in glass packages like an automotive fuse. This, like restoring a radio, will be a matter of personal taste and isn't something I see as a priority due to the effort required and the fact that the new components are only seen if the chassis is extracted from the set. If a replacement component is on top of the chassis (rare situation) then I would try to keep it looking original, regardless of the age of the set.

HMV Little Nippers, along with their AWA, Astor and Kriesler competition - all in coloured plastic - may not be worth as much as coloured bakelite sets from the 1940s but they are still invaluable in a historic sense so the 65-52 is definitely worth preservation. The other thing is, and relates to Marc's comment about the speaker transformer's mountings, even these late model radios were built like tanks inside. The original will have at least two screws but if there is only one now, it'll more likely be due to a lazy serviceman or home handyman. Just for the record, HMV radios were made at the EMI factory on Parramatta Road in Homebush, NSW not far from Olympic Park. It is right next to the famous 'Arnotts bridge'. This building still stands and is occupied by Kennards Storage.

Little Nipper, If you have some photos you'd like included in your posts you can e-mail them to me and I will insert them for you. Don't worry too much if they are not the correct size, though they should be as clear and sharp as you can get them. My e-mail address is on my profile page.

One last thing - it is unfortunate that the dangerous substances manufactured in years gone by work so well that they are superior in almost every way to the supposedly safer ones that replace them. This includes the poly-chlorinated biphenyl (PCB) that Marc spoke about and asbestos, both of which can be found in quite a few old radios. Both are safe if left alone though in the case of capacitors containing PCB, it is wise to replace any caps that are known to contain this chemical. If the capacitor ruptures whilst in service it will spray the chemical over other parts of the chassis along with the rest of its innards. The disposal of PCB and asbestos is also regulated - these need to be double-bagged and taken to the tip for correct disposal. Because of this, not all tips accept them - consult your state government's waste services website for more information.

A point of significance when taking photo's of inanimate objects at close range. ("still life with flowers".... in vase)

Many of the small non adjustable "snapshot "camera's cannot focus close. There is also the risk of the flash (where used) washing out the photo, especially on aluminium chasses.

In situations like that move back & crop latter & perhaps place a piece of white tissue over the flash to difuse it.

No matter how good you think you are, hand held photo's close up are liable to be unsharp, as you will move. The closer you are too the target the more significant will be the blurr.

A tripod is recommended.

Marc

Marcc,
I have put new capacitors into old cans on television sets before. I wonder if resealing a cap will make it last longer if it tests Ok. My next idea was to unroll the first turn or two and stick it to the new cap. Thanks for the PCB warning.
I am not sure of the 'can' transformer you mention, mine is an E type. The laminations are in the shape of an 'E' and it has a metal band with mounting holes going up, over and down the other side to the other mounting hole. they sometimes have another band going across the bottom to the mounting holes to hold the core firmly. Is the 'can' a metal shield over the whole transformer like the PT in the valve amp I had when I was a kid? What is an ISO?
I guess if it is not origional there is no point in making the caps look origional.
I am not a camera person but the HMV service manual should have a parts location diagram and a parts listing.
'Inside the pan'? Do you mean underneath?
Both of these transformers are on top of the chassis. It has a ferrite rod antenna 8" long.

GTC,
Sorry I unhid it las night, then I had trouble changing the address. Obviously the change did not take.

Brad,
I know these are only plastic but as somebody else here said "I had one of these when I was a kid".
What I would really like is a FM radio. Were any of these made in Australia?
It is a pitty we got sucked into changing our fridge gas, I have a couple of old ones and they are much colder and the duty cycle is far less than the new ones. Now we burn more coal to keep our food not quite as cold. Where is the common sense in that? That was the ozone hole scare, then, like the scientists said happens naturally, it closed up and they found somethiing else to bang on about. A new ice age wasn't it?
Asbestos is still used in top quality brake shoes among other things. Where is the asbestos in radios?
This carbon tax will be a good thing. It is about time someone stopped the volcano's from erupting and disrupting the worlds transport. If they do dare to erupt the tax on the emissions will far outweigh the losses incurred by the airlines.