HMV 1124 Versions ?

[davidgem1406]

I have here an HMV 1124, as stated on the label, that I have been asked to look at.
The manufacturers service data is on the Service Data CD-ROM.

However the service data shows this model as being an AC only set but the one I have is an AC\DC version.
The transformer mounting has been plated over and a large dropper fitted in its place.
Also the valve bases have been plated over and it uses a lineup of B8A Loctal valves.
The rectifier is a single diode type as would be expected.

Has anybody met this version? or knows of an available service sheet?

Thanks Dave.

[Radio Tech]

Could have been modified for some reason, perhaps there may have been a problem with heater voltages matching replacement valves that are not specified in the original circuit.

Ken

[davidgem1406]

Hello Ken,

Somehow I can't imagine anybody going to the lengths of changing it from AC only to AC\DC because of valve specs.
Finding a suitable dropper assembly would have been a major problem to start with.

The valve types are given in the service data (manufacturers at least) if not shown on the circuit diagram.

I would say it was done in manufacturing as the joints still show the dabs of inspection paint, including valve bases.

Thanks
Dave

[Mike. Watterson]

What valves does it use? The regular version is a little like the earlier model in the less rounded case, with a strange line up (B7G valves, X78 frequency changer that has to wire one heater wire to cathode due to only 7 pins and Octal output).

Perhaps it was export or for a rare DC mains area (though you say it has rectifier). Or perhaps an end of production cost saving.

I have the earlier one:
http://www.radiomuseum.org/r/hismast...21hmv_112.html

What yours should be:
http://www.radiomuseum.org/r/hismasters_hmv_1124.html

B8A Loctal valves.

You mean rimlock?

The last one related to 1121 /1124 a couple of years later is AC only.
http://www.radiomuseum.org/r/hismasters_1126.html
It is basically putting N78 (B7G) instead of KT61 (octal)

Baffling.
I agree, it's not something a user or service shop would do.

[turretslug]

Interesting find- every now and then, there's a "mains supplies"-type thread here so there may have been lingering need for DC-capable sets well into the 'fifties that a few manufacturers found worthwhile. There was an established series of M-O 100mA B8b loctals that would have been suitable, it may have been that at the time of design/construction that commercial politics ruled out the use of Mullard B8a rimlock.

[davidgem1406]

Hi Mike,

Thanks for your input.

The cabinet is indeed that as from the 1124.

The valves I called them "Loctal" as that is what the valve data program called the rectifier. They are B8A "Rimlock".

The line-up is as follows, this set has 6 valves, not the usual 5:
V1 markings worn off so don't know.
V2 X142
V3 UF41
V4 UBC42
V5 N142
V6 U142

The tuning scale ranges in metres are as follows:
LW 720 to 2000
MW 187 to 582
SW1 50 to 187
SW2 15.9 to 52

I don't know if the serial number may help but that follows if I can write it as is:
Serial Number A/7 26169 But the / represents the character Ѓ (without the accent) with the A above the horizontal bar and 7 below.

I have also added top and bottom chassis views, you will see that the bottom also varies from the standard 1124 with an additional tag board and components plus a smoothing choke.

I wonder could this be a Marconi chassis planted into an 1124 cabinet?

Dave

[davidgem1406]

Hello all,

The problem is solved!

The chassis is a transplant into the 1124 cabinet from a radio gram.
It is either a 5411 or 5412 chassis, exactly which is not determined as yet.

I just happened to stumble across a chat in a forum about an "1124 radio gram in peri!" and found a clue to mine being from a radio gram. The clue was the mention of the type numbers for the output valve and rectifier.

Checking the service data for both chassis clearly proved mine to be one or the other of them, both have the same layout and are AC/DC chassis.

Dave

[MurphyNut]

I have both a 1121 and 1124 and they look identical inside, just the cabinet design different the 1124 also being bigger.

[davidgem1406]

It transpires that the chassis is that of the 5411 with some slight mods, such as the output valve cathode components going directly to chassis, not via a winding on the output transformer.

I now have to find some correct pilot lamps at 5V 0.15A E10 (MES). The existing are all 6.5V and mostly 0.3A. That's not too good as it is a series chain for valve heaters and the lamps.

Dave

[Mike. Watterson]

You can use different volts, but correct current as it's series.