Fidelity HF1 record player
Fidelity HF1 record player
Got one off these coming to rebuild from friend of a friend, anyone got the circuit? Not on Forum CD or in the Red tv/radio books.
Please send PM if you can help Thanks
p.s. I have no access to Library
Can’t help with a circuit but if it’s just a simple record player audio amp it should be similar to other audio amps made around the same time.
When you receive it post the valve line up and there will hopefully be something similar available.
Is this going to be a "One Valve Wonder" amp, I wonder? - UL84 plus
UY84 UY85, typical of the time.
If so, there are a good few simple amps that could be substituted, or even borrowed from other applications (TV/radio output amps). Moreover, there will be a mountain of other record players which used the same, or very similar, circuit.
As Frank says, we can look closer, once we know 'what's in the box'.
This'll be "Boys Own" stuff taken straight from what we used to call the "serving suggestion", aka the suggested circuit on the valve's datasheet.
Although I never did 'get' why Dansette/Margolin's hobbled the performance of the early "Automix" by feeding the UL41's anode from the smoothed supply of c. 110v when Mullard's own suggestion is to feed only the screen from the smoothed supply and the anode direct from the rectifier cathode - I've modded a couple of them like this and you get a useful increase in volume with no increase in hum.
Interesting, the only reference I can find for Fidelity H.F.1 is here:
Reading through text, a reference is made to the output valve being EL84 and a typical two valve design, presumably plus rectifier, which according to snippets elsewhere suggest a 6X4 with mains fed directly to the anodes via limiting resistor (s). Strongly suggests a live chassis with the transformer supplying 6.3V only for valve heaters. Of course it may be none of the foregoing!
That's almost as nasty as a Trixette 78-only thing I have where the valve heaters are fed off a transformer and the amplifier HT comes from a metal rectifier fed off the junction of the two 120V motor windings in series!
I am modding that into something more sanitary that also involves an EF40.
@marconi_mpt4 Assuming of course, that the reference to "two valve" isn't just massaging the presence of the rectifier to make it appear more impressive. In the link, it refers to a high output crystal cartridge being fitted to bring it back to original spec. If that is so, then I'd say the EL84 (output pentode) is doing all the work, and the second valve is just the rectifier, ergo, a one valve wonder!
Had there been a triode ahead of the output pentode, a medium output crystal cartridge would have sufficed, or even something like a BSR SC4M ceramic could have been employed. An ECL84 (triode/output pentode) could have been a likely candidate in lieu of the EL84, for improved gain.
If the OP can post a picture when he gets it...
I've seen people put in a high-output cart when it doesn't need one but for those of us brought up on the UL84/UY85 combo...
Now wouldn’t it be a nice surprise to find a pair of ECL82’s and Push Pull output. ?
My first bet was a UL41 and a UY41.
So it will probably be something entirely different, such as an EL84 already suggested in the link shown by Rich. ?
No it was just a thought, perhaps not a good one, I am definitely interested to know what’s in the HF1.
This turned up last night a quick peep inside ,there is a valve missing 7pin I guess base (B7G ?) rectifier EZ90 ? other valve is a EL34
Cartridge is yellow bodied no markings but fitted with a ST12 stylus
There’s not much in it, referring to the UKVRRR thread it’s probably an auto transformer so will be a live chassis.
Check the wiring to the output valve to confirm it’s a pentode and not a triode pentode, someone may have put an EL84 by mistake. Perhaps unlikely but worth checking, again checking the wiring to the other valve will confirm if it’s a EZ90.
Once you have done that you will know the circuit and perhaps not require a manual. There can only be a handful of components in the player.
It really requires a high output cartridge if it’s just an EL84, the cartridge type should give that information, I have forgotten all the permutations from different makers.
It’s nice and clean inside with no damp or infestation, the record player is of it’s time, never going to be hifi but whoever bought it when new would have had a lot of pleasure listening to it.
@nuvistor Frank! - Now you're being silly. ?
Of course, someone could have revamped the amp, but somehow, I think not. Unless of course, you know differently. ?
Like I did with one of these many years ago when they were much less sought after....I built a Mullard 3-3 into one. Had to fit a much better speaker as well but it did sound good.....
...there is a valve missing 7pin I guess base (B7G ?) rectifier EZ90 ?
6X4 is equivalent to EZ90 and might be easier to obtain.