Fidelity TR19

[ekcopyephilips]

Hi Guys

I wonder if anyone would be able to offer some advice for the above.

A few yars ago this machine started to puff out clouds of smoke, i discovered that the mains transformer was getting hot and wax was melting out.

I took the transformer out of the chassis, powered it up with a dummy load and not a prob, - back into chassis and it gets hot and spits wax and smoke everywhere.

Where do i start, ive never touched valves before, any pointers would be good.

It has three valves in the chassis, a Mullard EL84, a Brimar ECC83 and another Brimar one, i could not get to the number , but it is used as a recording level indicator.

Its made by Fidelity Radio, the model is a TR19 and the serial number is 14423

Thanks for any help

Mike

[ekcopyephilips]

Sorry i should also add that after it puffed out smoke, it was put in the loft for the last 10 years.

[Michael Maurice]

You should not try and power this machine up from the mains until you have completed some checks and trsts.

It almost certainly uses a selinium diode or other semiconductor diode in the HT supply, this may have gone leaky or short circuit.

As you have stored the machine in the loft you should check the HT smoothing caps for short circuits and then reform it, checking the current that it draws.

Capacitor reformation is discussed elsewhere on this site.

When you are satisfield that the HT rectifier is OK and that the smoothing block is OK, check for short circuits across the HT supply.

Only when the above checks proove 100% OK can you power up.

Valve electronics lend themselves to staightforward fault finding.

[DOFFERY]

Hello , You will probably find the tranny has gone , they were cheap items fitted to the lower quality machines & wouldn't stand too much overloading & neither were they protected . However after checking the other items mentioned in prior replies a replacement shouldn't be too difficult to locate they were nothing special.

Doffery

[SA-Draadloos]

Originally Posted by ekcopyephilips

Hi Guys

I wonder if anyone would be able to offer some advice for the above.

A few yars ago this machine started to puff out clouds of smoke, i discovered that the mains transformer was getting hot and wax was melting out.

..........

It has three valves in the chassis, a Mullard EL84, a Brimar ECC83 and another Brimar one, i could not get to the number , but it is used as a recording level indicator.

Its made by Fidelity Radio, the model is a TR19 and the serial number is 14423

Mike

I just picked one of these up one of these for about half a pound (after currency conversion) even VERY cheap here in RSA. Anyway I don't know if you need more info? The PCB is marked "Fidelity PLaymaster" and is identical to the playmaster circuit found in Hellyer's tape recorder servicing manual. The indicator valve is an EM87 and is a ****** to get out of the clip which holds it in place.

I have worked on two of these before and both sets have the same problem. The secondary winding of the output transformer was open on both. I would replace this if I was you - the original ones quality is very poor. The mains transformer is also of poor quality.

The function selector (play, rewind etc) stuck at first. All the grease has gone hard. It will require you to dissasemble most of the parts, remove the hard grease and apply fresh.

The actual electronical part is straight forward : replace all paper caps and electrolytics (there are only about 8 components to replace). Lots of contact cleaner in the pots and it fires up the first time.

Sound quality is poor -

Good luck if you are still working on it,

James

[AndiiT]

Hi,
The Fidelity TR19 (also known as the Braemar) is a cosmetically "souped up" version of the Fidelity playmaster so from a repair point of view the circuits and mechanics will be similar, if not the same.
The tape deck (mechanism) is a BSR TD2 which is known for the hardened grease problem (this also affects BSR record decks)

It is likely that the selenium rectifier has gone short circuit or leaky causing the transformer to overheat (as has already been said there isn't a lot of protection, if any, in these machines) also with a machine of this age it would be wise to replace the smoothing capacitors, which I believe are situated in a "multi - can" and will be something like 32 + 32 + 25uF, the 25uF one being the output stage cathode decoupler, voltage wise the 32uF sections will be around 385 Volts DC working and the 25uF section something like 25 Volts DC working.

For reference the "Magic Eye" indicator valve will be either an EM84 or EM87

Regards
Andrew

[ekcopyephilips]

Hi all

Just an update, I dismantled the original transformer to transformer and found that in insulation breakdown had occured. The HT winding insulation on the secondary side had been damaged by a metal tag that the primary side mains input was soldered to.

I found a perfect replacment from www.maplin.co.uk Order number N90CC priced at £17.01 ex vat. Only available on net though.


Fitted tonight and works a treat, the mechanism now needs a clean and re-lubrication. Incidently what grease should i use ? Will silicone do or just normal LM grease.

Sound is fine from it too, found some old tapes at my grandparents and played them. Weirdy heard my dead great grandfather quoting that it was july 1969 and someone was about to land on the moon.

Anyways thanks for all the help guys. Its very much apprechiated

Mike Burton

[Mike Phelan]

Mike
Silicon grease is usually not a very good lubricant; I use LM or similar, and sometimes clock oil in various grades.

[Nickthedentist]

Well done Mike!

Make sure you dub those recordings onto another medium for safe-keeping (but keep the originals too, of course!)

Nick.

[Mike Phelan]

As an addition, as it is a BSR deck, it is not too much hassle to dismantle it completely including the motor, and clean and lube the lot; it will last another few decades then. The top motor bearing on these collects dust which leaches out the oil.

A good tip is to smear grease on the hairpin spring on the right to stop it rusting and breaking. The same spring was used in the UA14 etc record deck and the same applies to it, likewise the motor.

[ekcopyephilips]

OK guys another problem with this one

Ive just been dismantling the mechanical bits out in the garden as its a lovely hot sunny day here at the moment and i noticed that the speeck coil output tranny is showing signs of spitting its wax out.

Checking over the cct diagram i noticed that the cathode bias resistor (R17)should be 150 Ohms, but is actually reading 197 Ohms. This is for valve V3 which is an EL84.

I dont fully understand valve's and their biasing, could someone explain if this change of value is causing a problem in drawing too much current ? The body of it is marked as being a 150 Ohm component. Also what wattage resistor and type should i use as a replacment.

Incidently, thanks mike for advising me to totally re lube the mechanics, i now have rewind working perfectly.

Thanks

Mike Burton

[Station X]

The cathode bias resistor will carry the combined anode and screen currents of the EL84. 57 mA according to my tables. Using Ohms Law this gives a cathode voltage of 57*150/1000 or 8.55 volts. This is effectively the negative voltage on the grid.

If the value of the resistor has increased the grid will be more negative, which will DECREASE the anode current. This should give the o/p transformer an EASIER life.

The usual advice. Check for a POSITIVE voltage on the grid measured with respect to chassis. There shouldn't be one. Check and if necessary replace the coupling capacitor from the anode of the previous stage to the grid. Also check any cathode bypass capacitor, which may have gone leaky causing a decrease in cathode bias resistance.