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Radiogram, no sound

rematzz

Sep 23, 2015
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hi, i have posted questions in other areas about other things to do with the radiogram.
anyway it is a regentone arg 80, the date stamped on the inside is the 27th of march 1956.
it has 6 valves inside which are, EL84,EABC80,EF89,ECH81,EZ80 and ECC85. i have replaced EL84 and i have ordered a replacement for EZ80.

the problem is that the only sound i get is a hum, i don't get any sound from the radio or the record player.

i've tested the speaker and the speaker wire, they are fine. and the radiogram powers up, lights up and the record player spins, theres just no sound.

i'am really stuck and could really do with someone giving me a bit of advice.

thanks for any help in advance
 

Martaine2005

May 12, 2015
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Hi rematzz,
Check out "Mr Carlson's Lab" on youtube.
He goes into great detail about fault finding and repairs with valve equipment. Also up to date electronics repair too.
Very knowledgeable guy and easy to understand.

Martin
 

rematzz

Sep 23, 2015
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thanks martin i will have a look when i get the chance.

GPG, i did have a look, but a friend managed to get the schematic's from a different website for me.
 

duke37

Jan 9, 2011
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The first thing to do is to check that the EL84 is not passing too much current. I have not got the circuit but would expect that the cathode should be about 7V above chassis. If it is much above this then switch off quick and replace the capacitor feeding the grid.

Touching the volume control contacts with a meter lead should give clicks and hum. This will prove that the main power supply transformer, rectifier, speaker transformer and speaker are all working.

From what you have said it appears that most of this is working.

Next job is to measure the voltage on the valves but you should only do this if you are safe with high voltages.

Edit Are you far from Matlock?
 
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rematzz

Sep 23, 2015
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i have removed EZ80 and the hum went away, could that be the source of my problem?

duke37, i'am near pontefract, if matlock is where i think it is, its a bit far from me.
 

Martaine2005

May 12, 2015
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The EZ80 is a rectifier. I have no knowledge of valves what so ever. Except some have heaters that short etc.
And they bite too.

Martin
 

duke37

Jan 9, 2011
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Yes, the EZ80 is the high tension rectifier, removing this will stop everything working except the dial lights

Pontefract is a bit far, I will have to satisfy myself with a Pontefract cake.:)
 

rematzz

Sep 23, 2015
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so, if i replace the EZ80, could that fix my problem.

duke37, enjoy your pontefract :)
 

duke37

Jan 9, 2011
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Replacing the rectifier will energise the set but I would be very surprised if it would cure the problem.
You need to measure voltages without killing yourself to see if they match the circuit diagram.

Make sure the EL84 is not passing excess current either by measuring the cathode voltage or the voltage across the output transformer.

It is more likely to be a switch problem or a volume control problem.
 

rematzz

Sep 23, 2015
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i have measured the voltage from the output transformer, its was .004 to .003

i tapped the volume control tabs and there was no sound at all, no hiss or anything apart from the hum
 

rematzz

Sep 23, 2015
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also i checked the resistance of the volume control and checked the ends and wipers of it. the resistance was about right but on the multimeter the needle was jumping sharply when i was moving the knob slowly.
 

duke37

Jan 9, 2011
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Measure the DC voltage across the primary of the output transformer and calculate the EL84 anode current.

Measure the voltage on the primary of the output transformer relative to chassis, this will tell you if the EZ80 is doing its thing.
 

73's de Edd

Aug 21, 2015
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.



Sir rematzz . . . . .

Looks like "we" are being an "also ran" in your quest for repair info for this unit . . .as was being verified by:
Do read this . . . . and then remember back.

http://www.lencoheaven.net/forum/index.php?topic=21333.0

( Looks like that sets underchassis needs a dusting and vacuuming . . .Baaaaaaaaaaaaad.)

That Regentone is one nice sounding unit, that is from circa 1955-56-57, and you should be proud to have it,
and when it is properly operating, to be the envy of any younger generation observer.

Here is a photo of the Regentone factory in Elmsford, just 2 years before they started the manufacture of YOUR radio:

factory1954.jpg



BTW those "mystery" electrolytic capacitor are C54 and C62 , and I have marked them on the now supplied schematic.

C54 is a summing capactor being used in the FM radio portions detector stage.
( IT would NOT be THE bottleneck,in respect to your currently experienced problem(s) )
Its fault would be weakened or distorted sound when being in FM mode.

C62 is a cathode bypassing capcitor, and its decreased capacitance would cause decreased low end bass tonal response and
a bit lowered overall gain /volume in the EL 84 Audio output stage.


BEHOLD . . . .I now present . . .your custom drafted, ONE OF A KIND schematic.
It is taking the manufacturers schematic (across the very top) which they had made as TWO separate pages, but I have now
UNITIZED it into a one page, linear, cross flowing schematic.

In the mid portion, I added your tube basing info, along with their typical expected voltages being over to the right.

And finally, a pictorial view of the units under the chassis components and their locations.

SFZlnEH.jpg



Now, grab hold and hang on tight and I will give you a rundown on its analysis, enroute to its repair.
You said that all tubes were lighting up but said that the sets EF89 IF stage tube was open from pin4-5.
So that is one that you will be needing for the radio portion to function.
HOWEVER . . . .we don't even NEED it to further test out the probable cause of no sound from the set, since
your phono SHOULD have operated, to make some sound . . . IF NOT, its cartridge's output has declined and failed you with age.

Since you have used an ohmmeter, that means that you can also use that instruments AC and DC voltage functions for
rudimentary voltage measurements in your further troubleshooting.

I believe that what is going to be, your MAGIC FIX, is the replacement of the C63, C64 and C59 main power supply filter electrolytics.
I have them marked within fine RED + YELLOW boxes.
The sets B+ power supply section starts at the V6 / Easy 80 pin3 cathode and passes up the RED arrow path to C64 where
it produces some massive ripple reducing filtering and then passes on up to the the audio output stages T1 output transformer
between its a-b windings junction and reduced voltage can flow down and out of "b" winding and down the BLUE arrow path to the EL84
or it can flow upwards out of "a" winding to R40 being used as a filter/voltage dropping resistor.Then the reduced voltage out of R40
flows down and thru R39 to provide screen voltage at the EL84 pin 9.
Take note that another significant function of R40 is to pass to the left and tie in to C63 filter cap to get even MORE filtering
of that reduced B+ supply line which goes to the LEFT and feeds voltage to ALL of the rest of your radio.
FURTHERMORE . . .then there is connection to R34 . . . which reduces the level of that B+ supply, yet a bit more and is using
C59 for its filtering.
Now go ye forth now and locate electrolytic capacitors C64----C63---and---C59, and if you track down the wiring paths to them,
I believe that you will find all three of them being contained within a "canned electrolytic".
Find my Green boxed R40 and I believe that electrolytic cans location is being the circle behind it.
On the top side of the chassis, you should be able to read the markings on that can, as to their Ufd values and voltage ratings.

One final question . . . .is if that HUMMMMMMMMMM, coming from the sets speaker, can be diminished by turning down the sets volume control.
If not . . .since I am deaf at this end . . . .is that HUMMM .... being 10 thru 90 % of the sound level you would normally listen to the radio at.
OR it COULD also be strong enough, so as to be 100% 200% 300% in excess.

Thassittt . . . .gonna let you go now and explore with a bit of your new found olde tymes ray-dee-oo knowledge.

Then . . . . . I will be asking for you to make some specific voltage measurements.

Aside adjunct observation:
I wunder whin "spell check" wil ever be larnin' hows to spels "electrolytic"

ADDENDA:
In rereading that comment of yours, on the first forum, there,you did not seem to note the hummm as being overly loud.
If that is the case, lets just jump forward a bit and have you measure the DC voltage on both sides of R40.
Have your meters negative probe connecting to any component connected to that HEAVY BLACK ground buss
Then check both sides of R40 with your meters + probe.
Main initial attention is being its lead that goes to T1 for ~260VDC and then . .AND THEN . . the other side
. . . . is it anywhere near that prescribed ~235VDC or is it down towards ZEEEERO ?


73's de Edd


.
 
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73's de Edd

Aug 21, 2015
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Clarification:
On the very last of the post above just before the 260 and the 235 I had placed a tilde to designate approximately . . . and this woooooooosy calibri font placed a minus sign instead . .
so note those entrys as being approximately +260 VDC or approximately+235 VDC . . . . . . .calibri . . . . .jeeeeeez.
 

rematzz

Sep 23, 2015
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i checked the phono cartridge in a different record player and it worked, so that is working, theres just no sound getting through at all.

also i still haven't found the capacitors, also thanks for schmatics, but it all looks different to the one i have and also it looks different to the circuit.
 

73's de Edd

Aug 21, 2015
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Sir Rematzz . . . . .

Its gotta be the same in our primary points of interest in its EZ80 and El84 circuitry, the first consideration
would be the presence of those 2 voltages on the EL 84..
Your prior test of the EL 84 revealed mere millivolts ? BUT with the set having its EZ80 plugged in and producing a hummmmmmm
would thereby verify the EZ80 supplying some higher order of B+, and it then being present on the EL84.

Confirm if you had a valid ground point as the meters negative probe reference.OR that the meter was not in its AC mode.

73's de Edd
 
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rematzz

Sep 23, 2015
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the voltage measures i did last time was in AC, i have just tested them again in DC, i measured it again on the two wires go from the output transformer to the speakers, it was -0.001 so i measured the voltage on the blue wire to EL84 and on the black wire to the speaker, it started at 3V and rised to 8.35V before i turned it off, the voltage just kept going up.

2015-10-16-203605.jpg 2015-10-16-203640.jpg
 

73's de Edd

Aug 21, 2015
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OK your DC mode is NOW correct and your negative probe to the wire from the speaker that is going to ground is correct.
Not sure if you are getting to the right place with the + probe so UNPLUG the EL84 and set aside and then CORRECTLY find its pin 7 and fire up the set
and see how high the voltage on 7 gets, and if right on up there in the expected 100's of volts.
Then shut down power and plug in the EL84 and then fire up the set and take measurements again, and make that same measurement.

Then we will know if it might be that the conducting EL 84 is PULLING down that voltage.

But I wouldn't expect a pull down al l l l l l l the way to a mere 8 volt level.

And if you were getting right on up there in the high voltage levels, I also need to know the voltage on pin 9 of the EL84

73's de Edd
 

duke37

Jan 9, 2011
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Coloured wires do not help much. Measure the DC voltage relative to chassis both sides of R40.
Measure the cathode voltage (pin 3) of V5, the EL84. It should not rise above 8V. if it goes above 10V, then switch off.

Measure the anode voltage of V5.

If these are all correct, then you shoud get clicks when touching the volume control.

The set will not work if the voltages are way out.
 
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