Worth a try GTC at least, your experience here exceeds my own... It is maybe a little hopeful, but possible whatsisface has somehow compensated for the missing cap, but if he's that clever I'm sure he would have not left that one there... But... People do very strange things! But not me... I never work on cars or radio's when I'm on the piss lol, I don't even drive them anymore, just listen to the radio and have another drink! Cheers.

The line transformers are very easy to mod and they do work.. If I can do it then you as a mechanic should find it easy. Also you might check to see if a resistor has gone high or out of wack in the circuit effecting the electro that was left disconnected.

There's no way to compensate for a missing filter capacitor unless one thinks mains-related hum is normal and I don't know any repairer who fits that category.

It's possible that a fiddler discovered that disconnecting the old cap made the radio work (stopped the rectifier running red in the face and transformer from getting very hot), albeit with hum resulting.

No Robbbert sorry, GTC emailed it to me, but I don't have yours

Address has been unhidden.

Well I tried that, unclipped the newest cap, it's still a softly spoken fuzz box... I give up for now, but I'd expect on the 20k range a reading of 10k, at leat 5k ohms, not .59k ohms, in other words 500 ohms? if that's a true reading, the output transformer is looking like it has an internal short and is consequently distorting the crap out of the output, which would be over working with no reward in the volume department? Anyway I'm over it for now, it can sit in the sick bay until I get my enthusiasm back. Elation to disappointment was a bit quick on this one, time for a scotch and to listen to one of my better behaved ones!
Cheers.

Output transformers generally don't cause severe distortion.
They either fail totally or go OK.
Without a circuit its a bit difficult but I consider you have either a man made fault or something else has happened.
But highly unlikely to be transformer, power or output..
I certainly would not be ordering transformers especially from overseas, If you have to, scrounge one out of a wrecked radio.
JJ

Ye GTC, that's my theory too...Cool Robbert will email you. The hum didn't come back when I removed C23 (the one left previously disconnected) But it is part of the schematic and therefore should be in circuit. When I "fix" something I usually leave it on for at least 24 hrs, if it deteriorates in performance (hasn't happened yet) Then I wouldn't consider it fixed... Maybe that's why I got it cheap, if only I'd shut it straight off when I heard the hum and replaced the caps then and there instead of assuming the recap was done as it should have been. I'm guilty there assuming the hum was normal, given that I've had ones that hummed before I knew about faulty leaky caps , which didn't self destruct over a matter of hours, if It had been one I'd bought and I'd not been told it was re-capped, I would have investigated immediately, but alas assumed It was re-capped, not partly re-capped. My error of judgement but I don't think it's an easy fix now. I could probably convert a line transformer, options must be considered I suppose...

I'm a little confused here.

According to the service manual the HMV C13D is a MW/SW plastic mantel without a gramo unit, although there is provision for a pick-up.

Some pics would be good so this unit can be properly identified.

Well Johnny that is my hope, as if there was current likely to overload the transformer, it would be drawn through the second grid of the 6m5 to the anode, so I'm hoping it's just a damaged valve as that's just a plug in fix... In any case as soon as my parcel of two 6m5's arrived I shall either be dancing on the ceiling or curled up in the corner whimpering lol
Thank you, in any case whatever damage occurred happened over approximately five to six hours, I thought it was just atmospheric interference as it was raining outside and stormy, but not so lucky it's a muted fuzz box now, Bummer. Be nice to get it out of the sick bay, I will eventually no doubt. Must be something simple gone wrong in any case! Thanks guys.

The Nippergram is model U63C, whose schematic is very similar to C13D, apart from gramo.

Does yours look this this, Jamie?: https://www.youtube.com/watch?v=KLq_X0hROSQ

I shall either be dancing on the ceiling or curled up in the corner whimpering lol

Despair not. It will be fixable.

Just a question . Is the output negative biased. If it is then I really think you maybe correct in guessing the output tranny is oc. In my little nipper super 5 this was the case. I was also able to hear very low volume distorted as well and the transformer was open circuit. My buddy who is a valve era tech was puzzled when he found the tranny oc as he had never experienced that before.

Hi Monochrome, yes it's a small tablegram, must use that chassis, will email Brad a photo, have put it back together for now as It's not looking like a quick or easy fix, I did the electrolytic caps, the rest are new but no workey... Not properly anyway.

There's a negative feedback connection to the O/P transformer's secondary.

Thanks for the schematic.

Now, things to check (if you haven't already done so)...

Turn volume to zero, then measure around the 6M5.

pin 7 - 250 volts or more; pin 1 - 200 volts or more, pin 3 about 5 volts; pin 2 - 0 volts.

Turn radio off, turn your meter to ohms, measure pin 3 to ground - 200 ohms; pin 2 to ground - 550k.

Make absolutely sure that C20 (0.02uF) has been replaced either by you or the previous person.

590 ohms is fine for the output transformer. Remember, there's a big difference between the impedence the valve sees (7000 ohms), and the DC resistance.

Make sure C23 is in circuit, anything from 8 to 25 μF is fine.

Measure the resistance from C23 to C19, should be 5k (2x 10k in parallel). Sometimes you'll find that one of them has burnt out.

Measure R9, should be 250K, this resistor has a habit of going high. Replace with 220k - 270k resistor.