HMV 1124 - Has Been Tested And........

[Murphyv310]

May I add that you will see many of my photos of many restores, repairs and projects on the VRAT forum that I resigned from due to the intransigence of the Administrator and moderator.

You will also find my input including hundreds of pictures on the UKVR&R forum as murphyv310. I was a banned as a member because I stuck up for those with dyslexia and other issues!

[Nowhere-Man]

O.K., glad to see this thread hasn't been closed while I've been away. There have been developments in the HMV project that took me by surprise. It is actually now working and picking up lots of stations. In fact, not only is it now working as it ought to be but it's working extremely well, in terms of tone and audio. And, of course, I'm very happy about that as you can imagine. The only thing I ought to add is there is still a band (or two) on the waveband selector switch that are rebellious. However, Longwave was very lively and I was picking up Spain last night on my boat as clearly as you'd get a local station.

How did I get to this point? Basically it boiled down to 2 capacitors that I changed - one being in the grid circuit of the Double Diode Detector. This one was an audio coupling capacitor. I used 10 Nanofarads for the replacement.

Another development was what I found to be a miniscule short circuit in the system. This was barely visible and was only revealed after cleaning more wires with WD40 and cotton buds (as I do). You could then see tiny strands of wire projected through insulation but these had probably made contact with nearby joints. The serious swearing and cussing then began when I found there was no access to re-solder new wire so I had the job of manually insulating the wire with electrical tape + a dab of superglue. I couldn't get my hands in the gaps to wrap the wire which led to major frustration. Likewise soldering in the new capacitor where access at the rear was extremely awkward.

On powering on, I noticed lots of stations were coming in when tuning the V.C. but also a marked increase in speaker volume. Audio quality was very good indeed. I boiled the kettle and was unfortunately subjected to a speech by David Cameron.

At night I turned off all my ceiling lights and got onto Longwave. Spanish language reception was awesome and many other stations were picked up.

So, there you have it. I'll comment in my following post.

[Nowhere-Man]

O.K. thoughts and observations......

Firstly, apologies in advance that I don't have time at the moment to comment on any former posts. I just got to the library and was totally soaked by a massive downpour of rain. It's nearly 1700 p.m. and the library closes at 17.45.

I believe the approach I took to this radio has been justified by sufficient success in the point I've now got to. I'm a firm believer in not rushing this kind of work. The approach I took involved very cramped soldering and huge amounts of frustration because I chose not to dismantle the mounting strip-board which hosts about 20 connections to chassis points, tube pins and I.F. cans. I wouldn't recommend clipping out that many connections in cramped space unless you're sure you can put it all back with no error. Sure, it means you can make a tidier soldering job but, for me, at the time it was too risky.

The manufacturers had used pliers as well as solder and I had to snip parts out and only use solder to put the new parts in. I started to the left and worked my way to the right and tended not to remove more than 3 capacitors in one day. This was to avoid any mix-ups.

I take the point about RF hiss and long leads (which I used). Long leads are best avoided but I did the best I could.

I wonder why HMV used this stripboard method? Most radios just solder straight between tube pins so it makes repair 10 times easier. From the design point of view I was impressed by the way they fused the transformer mains supply and wonder how effective that was? They also mounted the rectifier on a platform and both the rectifier and the output KT61 were screened to chassis (I have yet to put this back in place).

Plans for the future? My plan is to specialise in tube radios as I feel I'm better on this than I am with silicon transistorised equipment. My immediate plan is to start work on a 1939 TRF which was an unfinished project. Eventually I hope to get into vintage German radio work as well as making my own HAM receivers hopefully.

For the meantime, I still have the case to fix up and the slats + tuning mechanism to work on.

[Nowhere-Man]

Only 15 minutes remain till closing. Some general comments:

My plan for on-going projects is to stick to the business at hand. On the whole I think Mark has done a good job in making this a more friendly and tolerant forum so I've no desire to cause any friction, given I'm a guest here same as the other members. This seems one of the more friendlier vintage radio websites in the community so let's try and keep it a friendly place where beginners will find a constructive and warm atmosphere (plus a sense of humour helps).

This thread has finally reached its conclusion and I'm going to chill out a bit and so some keyboard and singing practice over the weekend.

[pwdrive]

You've got the HMV going, that's good, some radios are pigs to work on some aren't so bad, keep at it.

Don't forget to post a question If there's anything regarding to radios etc that you're not too sure of.

Lawrence.

[tiv48]

Well done NM .
your HMV was not really a set for a beginner! something like a bush DAC90a would of been far easier ,but would you have learnt so much ?
I am guilty of repairing stuff and not posting on here mainly because it would become boring you know changed audio coupling cap and 3 decoupling waxies. radio now works!
I did contemplate doing a step by step repair on a few sets and may still do so so that beginners can understand the thought proses . the one thing i lack is time.
anyway all the best with future repairs you will look back on the HMV in a few years and wonder why you had so much trouble.
Rob T

[Crackle]

Well done, it is surprising how difficult it is to find a fault like a little wisp of wire touching where it shouldn't.
It may be possible manufacturers fitted components into "modules" like your double tag strip, and then fitted these into the set. It may have saved time.

This is a component board in a radio I am repairing at the moment, I would not be surprised if this was assembled outside the set and then wired in. There is another row of solder tags for the other end of the component leads the opposite side of the board (which indecently is only made of cardboard) hidden under the rest of the wiring. But this method of fitting components is probably easier to work on whilst carrying out repairs than the tag strips you had in the HMV.
   


Mike

[boater sam]

You have private messaging disabled, otherwise I would have sent this to you privately .

There is a workshop you may be interested in.

It is on the Vintage radio site.

"A two-day Radiophile Teaching Workshop will be held at Gnosall Memorial Village Hall, Gnosall, Staffordshire ST20 0ET over the weekend of Saturday 12th and Sunday 13th December. One-to-one tuition is provided by several experienced engineers and restorers, and small components are provided free of charge. Each day starts at around 9am and concludes at around 6pm. The cost has been pegged at £30 for either day, or £50 for the full two days. The workshops are suitable for all participants, including beginners, and no previous experience or skills are required. Bring a packed lunch, your tool kit, a soldering iron and two or three sets to work on! The aim is to get everyone's sets working by the end of the day.


To my knowledge, these workshops are the only available examples of hands-on tuition in vintage radio and electronics repair. For further details and to book a place, please contact The Radiophile by telephone on 01785 284696.

I have no connection with The Radiophile other than as a very satisfied customer of one of these workshops some time ago, and a volunteer engineer at these events for the past few years."




They are a friendly lot, you could learn a lot from them.


It may assist with some of the things you have struggled with.
Knowledge is power.


Sam.

[Murphyv310]

These are a great idea Sam. 
Something I'd be happy to do here for say two at a time and supply refreshments and do hand outs. 
Perhaps more of these "workshops" could be started, what a boost the hobby would have.

[Nowhere-Man]

Well done, it is surprising how difficult it is to find a fault like a little wisp of wire touching where it shouldn't.
It may be possible manufacturers fitted components into "modules" like your double tag strip, and then fitted these into the set. It may have saved time.

This is a component board in a radio I am repairing at the moment, I would not be surprised if this was assembled outside the set and then wired in. There is another row of solder tags for the other end of the component leads the opposite side of the board (which indecently is only made of cardboard) hidden under the rest of the wiring. But this method of fitting components is probably easier to work on whilst carrying out repairs than the tag strips you had in the HMV.



Mike

Was the tag-strip idea a good one? The way I see it maybe the manufacturers figured if a radio lasts 20 years, that's a fair innings. They probably never figured there would be a need to remove the tag-strip where most of the larger bypass capacitors were soldered in. However, on the HMV, it really was a nightmare. One day last week I was close to tears of frustration because I couldn't get a solder joint to hold. The solder point was deeply recessed to the point I needed a lamp shined on the joint to see where I was and the slightest movement would scorch nearby wires or components. It took half an hour to do the one joint whereas other joints after that took seconds due to better access.

Far better in my opinion not to use tag-strips unless some thought for access has been pondered.

I've often wondered about something, though, and it's a good question to ponder. How often did tube radios suffer a broken solder joint? What would happen if an HT lead at 230 VDC came off an HT can and then swung around till resting on the chassis? Would the fuse save the day and blow? Obviously there was no RCD back then and no earth wire. I often think there must have been incidents and the tag strip idea might have emerged due to that.