HMV 900 TV restoration.

[FERNSEH]

The rear lower batten has been removed and now I'm making a replacement.

The original part is used as a template.

DFWB.

[Mikeymushradio]

It looks like the usual over engineered build quality from HMV which is all very fine for longevity but not when you have to replace parts especially when you can't reassemble it in the original sequence.

Let me know if you are likely to need more blockboard.

Mike

[FERNSEH]

Hi Mike,
This is a tricky cabinet to take apart and reassemble. Lots of tongue and groove joints.
The replacement lower cabinet batten has been made and fitted. The next stage of the cabinet restoration is the lower side part.

DFWB.

[chipp1968]

I assume that the veneering was originally done prior to assembly , or at least that makes sense . There could be some cover up of ply edging. I have known veneer to cross joints in construction ,especially on early 18th century furniture , which causes problems as the wood moves and shrinks or expands. This cabinet being mainly block board and ply , with maybe some solid beech hopefully is more stable .

[ppppenguin]

Good to see this poor old brute getting better. I mean the HMV900 of course. It's also great to see that David is feeling well enough to do the work at all. Must have been the intravenous Newcastle Brown

[peterradio]

This is just fantasic, keep up the good work, can't wait to see it completed.

[FERNSEH]

The lower side panel is now fitted. The cabinet has regained it's strength.
Really strong and heavy.

DFWB.

[murphyv310]

Hi David.
The cabinet is coming together now very nicely.
I will need to start on the chassis soon now that it is here. I have looked at the power supply and see that the EHT smoothing capacitor has exploded, it will be an easy re-stuff though with a modern cap. This made me check the EHT winding on the transformer and unfortunately it is o/c. I intend to strip the full chassis and clean the metal work in acid or get my friend to sand blast it, this will be done while the transformer is being re-wound.
I think my progress will be slower as I have limited space and a few things to complete firstly.

[ThePillenwerfer]

I will be following your progress with great interest.

- Joe

[neil29]

The cabinet is coming along nicely Mike thanks to David's excellent work. and once Trevor finishes the chassis you will have a very desirable set. Cheers Neil.

[brianc]

Originally Posted by murphyv310

I think my progress will be slower as I have limited space and a few things to complete firstly.

Bring it on Trevor. I'm looking forward to the story - I chickened out at the NVCF and somehow, now, wish I hadn't - but there you go . Good luck to you, David and Mike.

[murphyv310]

Hi Brian.
Well this will be a labour of love! Due to the set's age and history all caps that need to be replaced will be re-stuffed in the original shells, I am lucky that I have a really big stock of 30's resistors that haven't succumbed to ageing.
I hope to start in earnest next week once a couple of other jobs are done.

[HamishBoxer]

Keep us posted Trevor,looking forward to all the pics. Must admit I didn't restuff my rebuild but it was many years ago. Don't think then it was really mentioned by anybody.

Regards David

[brianc]

Re-stuffing is a good idea with original components but all too often the caps are not original anyway so is there a point really? I like Steve's idea of putting black Hellerman sleeves round the bright yellow replacement caps which tones them down so that they are hardly noticeable. Tubular electrolytics are a different matter. Very often there will be at least one original and replacements can be made using gummed brown paper wrapped round a suitable mandrel and photoshopping a replica label. I now always do this.
Why is it that pretty well all new caps, by many manufacturers, are bright yellow - why not a nice waxy brown .

[murphyv310]

Hi Brian
I heard a joke the other day saying the modern caps are bright "Yellow" due to an HSE ruling!
Well at last I have cleared a space and the PSU is on the bench. other than the spewed EHT smoother and the faulty EHT winding on the mains transformer, I also see the mains input is set to 200-210v lets hope that was correct for the area.
I am hoping to strip the chassis tonight.

[murphyv310]

Of course the cap you see worse for wear in the photo is the main smoothing cap, it isn't the original pre-war fitment.

[Mikeymushradio]

Just had a quick look at the radio chassis and the mains tapping is set to 230-250 so that doesn't look good for the tv section.

Has anyone any idea what the smoothing block looks like in the radio as this one is AWOL, I have been searching for the service data for the table model equivalent but not had much success the nearest I have found is the HMV496 but the smoothers on that are mounted on the speaker.

The chassis has suffered from the damp storage with all the valves loosing their screening and all the wiring insulation having gone brittle and crumbling away when disturbed i am currently trying to find a suitable replacement sleeving,all the screened leads are also perished and several are shorted so these will need replacement again with something suitable,the dial cord has also rotted (good job it's not a Philips).

Once I have got all the caps re-stuffed and the sleeving replaced I will show it some mains and see what it does. I am expecting some coil trouble due to the poor storage although I have several '30s sets that have been stored badly and all eventually come to life with a little patience.

Mike.

Currently struggling with a Sobell T170 that had a pile of wood dust under it when i moved it the other day........ it lives in a wooden shed surrounded by lots of other woodies so it has now become a priority and the HMV is on hold at the moment.

Mike

[murphyv310]

Mike, Watch those little beasties don't have a chew at your coils

[brianc]

Hi Mike
There are two cap blocks in the radio section as shown in the attached drawing. They are, if my memory serves me correctly, mounted back to back on 2 brass pillars slightly longer than the height of the cans. The size of the cans can be ascertained by the fixing holes in the chassis and the fact that the 2 together are lower than the chassis depth. The other sketch shows the 2 blocks on the PSU and these, too, can be sized using the fixing holes. I had to make several cans for my early TVs and it can be great fun. I usually leave the base open for future restorers and mount the caps on veroboard. Good luck.

[murphyv310]

Hi Brian.
The two caps on the underside of the TV PSU have been replaced by the one tubular capacitor. It would be easy enough to make a repro "tin" box and mount a modern cap inside and spray the box grey, certainly this would be the best way to go. What do you think?

I have the 900 manual here, I would assume Mike has a copy too.