Thorn HMV 2614

[Iontrap]

Hello I am new here so bear with.
I have a dual standard HMV 2614. After the usual preliminaries it lives, the tube is good.
I'll bung up pictures once I get the hang of it.
Its running half speed at the moment.
I suspect caps. locking to mains.
Looking up this chassis it says it has FM radio. anyone know how this works?

[Iontrap]

A friend of mine says the settings on the turret H L T are home third and light.
How are these tuned?

[FERNSEH]

"Looking up this chassis it says it has fm radio. anyone know how this works?"
The 6Mhz TV sound IF amplifier and demodulator is employed also for the FM radio. For FM radio reception the CRT heater is taken out of the heater chain and the HT supply to the timebases switched off.
The standard IF for FM radio is 10.7Mhz but for most purposes 6Mhz is quite satisfactory for radio reception.
405 line Murphy TVs converted the TV sound IF of 38.15Mhz to 6.31Mhz for FM radio.

DFWB.

[FERNSEH]

Picture of the HMV 2624. Does your set look similar?

DFWB.

[Iontrap]

Yes thats the chap. Locked half speed. Dubilier caps in sync to investigate.
No results on 625 yet. It's a nice set though.

The Thorn 850 dropper was not reliable I understand. On this set it has been almost completely bypassed by external Rs. I was fortunate to buy a Radiospares R.21 off Ebay. I'll bung it in when all else is sorted. These ERG droppers developed hot spots on account of being flat/oval.

Many thanks for that Fernseh.
I have the 850 service manual. It has HMV 2613. Do you have the 2614 with radio?

[FERNSEH]

I believe that information for 850 series models with FM radio can be found in the 1964/65 Radio and Television servicing book.
I've got that book somewhere.

DFWB.

[Iontrap]

Many thanks for that. I'll obtain an update.
The 850 series manual I have is for a convertible. It has HMV 2613 in it. The HMV 2614 seems to be a factory fitted UHF set. The 2613 is 19" whereas my set is a 23".
Did many manufacturers go down the convertible route for 625?

[Amtec123]

Looks like a nice set for restoration.

[Iontrap]

Some pictures of the internals.
Note wafer switch which does the radio business. Needs a clean and I think a new mixer PC88.

The chassis is marked 850 FM I find. Now the fault finding proper gets started.
I'll concentrate on 405 side of things for now. Welcoming any guidance out there from folks who who worked on these in the 60s
I was two when this came out. We had the Ultra version which progressed to my bedroom as a teenager so I look forward to it.

[FERNSEH]

On most 800 and 850 series models the 405/625 switch was located on the left side of the cabinet. A few "de-luxe" sets like the HMV 2614 under discussion and certain Ultra models the switch is located on the front control panel.
On sets with FM radio the system switch will remain in the 625 position when the receiver is switched to FM radio.

DFWB.

[Restoration73]

I can't see the detail in the photo, but to actually tune the relevant H,L,T (Radio 4, 2, 3)
to the local FM channels (might not have changed if the set is in the same area) you
might need to remove the vhf knob to access the adjustable cores. You may find the tuning range is only 87-98 MHz as that was the FM band then. In my later 900
chassis set with FM, the vhf fine tune is a separate "push in and turn" knob, whereas
normally a vhf TV only set has an outer ring to the click channel change knob.

[dazzlevision]

Looking at the photos of the VHF turret tuner, I see it has those white plastic “fine tuning” screws with a gear wheel as the head - but fitted at the front. So, there must be a VHF fine tuning knob at the front control to adjust these. This should also fine tune the three VHF radio channel coil “biscuits”.

[Iontrap]

Yes indeed. There is a fine tune knob from the front. You push it in to engage with the turret gears. I am concentrating on the 405 side first what with a sync issue.
When I switch to 625 all a bit deaf so a new PC88 mixer is going in.

[Graham G3ZVT]

"A bit deaf" would be an understatement for a PC88/PC86 tuner even if it is working well. You would not expect much in the way of snow on the screen with no signal.

Here in Winter Hill land, you were lucky if the oscillator oscillated at the dizzy high of BBC2 (channel 62).

Tapping those frame-grid valves with the butt end of a screwdriver will often bring up the gain, albeit temporarily.

The pictures you posted take me back to my first job at Granada as a "Junior Improver" (tea boy and sweeper upper) at Langworthy Rd Seedley (Salford). Endless refurbishing of 850s and 900s.

I'd completely forgot about that die-cast fork arrangement that operated the system switch.

I could pop out, clean and re-tension the turret tuner contacts with my eyes shut!

[Iontrap]

Thank you Graham
I'll get it on my humble bench tomorrow and go from there.
I've done the preliminaries , reform, x1 cap and so forth.
Have you seen the sync lock in wrong place before? It doesn't vary as if it was a mains thing.
I have not been at this since the 80's when I did Philips G8 for a local rental chap.
We went to Birmingham and bought up loads I am sure old veterans will remind me of the establishment, I had reguns from PV tubes to bung in. And slotmeters.
I moved on to proper broadcast after that (Thames) but now retired I look forward to my next restore after my Bush TV22.
Whatever was that place in birmingham called? Always advertised in Television magazine.
Simon

[FERNSEH]

Hi Simon,
If you need any new PC86 and PC88 valves I've still got a good quantity of them in the shop.

Still haven't found the 1964/65 R & T servicing book which might have details of the FM/TV switching.

DFWB.

[Iontrap]

Thanks Fernseh
I have the correct info coming this way thanks to chaps on the forum.
Please give details of your emporium please.
I am still bugged trying to remember the ex-rental tv outfits where tellys were stacked high. Birmingham certainly but also Kidderminster I think.

[Pfraser]

'Sumik's' comes to mind.

[AJSmith625]

Ex rental TV outlets in Birmingham in the 80s
Hussain Central TV who I think were in Erdington.
Wiltsgrove, River street, Digbeth.
Colourtrade in Newtown
Norgrove later changed name to Nationwide, Aston Church Road, Nechells.
There were many more. Now why does the name Arthur Daley come to mind when thinking of some of these outlets?

Alan.

[Heatercathodeshort]

I have just last week overhauled a Marconi 850. All the caps in the frame timebase needed replacement to get a perfect test card with the presets half way.
There is a 22K 1watt resistor behind the 6/30L2 that reduces in value to the extent that it turns to dust. Frame roll/lack of interlace and frame tripping are all due to this anode load resistor going low.

Most of these excellent Dubiliar blue/white and gray caps are now becoming very leaky, not surprising after 55 years! Good luck with it. I repaired an endless stream of these early dual standard models. John.