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Old 11th Jan 2019, 9:17 pm   #21
Phil G4SPZ
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Default Re: Trio 9R-59D receiver problems.

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Originally Posted by Humptydumpty View Post
Funny thing about V8 shows less than 1 volt from pin5...
Hi Trev,

So far you’ve told me that the voltage on pin 5 of V8 is 40 volts, then 12 volts, and now less than 1 volt. I asked that you tell us the make and model of multimeter that you’re using. You also received some good advice from James Duncan about pulling out V8 and then measuring the voltage at pin 5.

Did you follow any of this advice? The answers will enable us to point you towards the appropriate next step. Electronics is just as logical as car mechanics.

Forum members have plenty of patience and are keen to help people who may be new to vintage radio repair. However you must realise that to enable us to provide you with the correct advice, you need to provide us with accurate information that is consistent.

If you don’t feel confident about tackling this work yourself with our help, you still have the option to post a request in the ‘service wanted’ section.
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Old 11th Jan 2019, 9:21 pm   #22
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Default Re: Trio 9R-59D receiver problems.

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Originally Posted by ms660 View Post
The difference...apparently:

http://televideo.ws/9r-59d.html

Lawrence.
Very good. There is a D suffix model then. I know that the circuits of the 9R-59DE and 9R-59DS are identical because at one time I had the user manuals for both sets and I compared the diagrams in the manuals.

I think the 9R-59D must use the same circuit.

There were some minor differences between sets. My DS model came with a wired up socket for a voltage stabilizer, but other sets had a vacant hole in the chassis.
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Old 11th Jan 2019, 9:32 pm   #23
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Default Re: Trio 9R-59D receiver problems.

Circuit extract attached.

I've found that where there doubts about a contributor's measurement techniques it helps if they post a picture showing where the test leads are attached to, what range the meter is set to and what's showing on the display.
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Old 11th Jan 2019, 10:43 pm   #24
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Default Re: Trio 9R-59D receiver problems.

David and other members . The transformer is out . So i need 5 pieces of coloured wire . Red green blue yellow black.
No Maplins to visit now that they have gone . Any ideas of a place that i can purchase from . Thinking about it it is not a problem , i have 3 tuner amps its time to operate on one of them for the wires i need. Shame i took the cover off the one last week to see if i could get a audio taper from it to fit the Trio , but they are not the same . Some workmanship inside those Sony tuners of the 1980 .. So i will get in there Sat to find the wires i need . The transformer will need to go on the side wall of the chassis . Let you know Saturday the out come of this episode .I hope it works .This move may work but if not i will go down another path .
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Old 11th Jan 2019, 10:50 pm   #25
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Default Re: Trio 9R-59D receiver problems.

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Originally Posted by Station X View Post
I didn't think there was a model 9R-59D, but I'm always willing to learn. Does it have twin round tuning scales?
Station x yes it has .The receiver is just the same as the other 9R 59 DS and the another model i dont know the other mopdel they are all on the same lines internaly .Do a Google search on it ,on the search page look up to the right you will see images - click on that and .Put in the search box Trio Radio Receiver 9R 59D or DS you will see them all in one place.
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Old 11th Jan 2019, 10:55 pm   #26
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Default Re: Trio 9R-59D receiver problems.

So you're going to reposition the mains?? transformer, with all the possibilities of introducing new faults, before you check out the problem with the voltage on the anode of the output valve?

There are plenty of places on line which sell coloured wire. You just need to do some basic searches on Google or eBay.
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Old 12th Jan 2019, 12:04 am   #27
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Default Re: Trio 9R-59D receiver problems.

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Originally Posted by Humptydumpty View Post
...I hope it works. This move may work but if not i will go down another path...
One that leads to madness, I think. I’m out.
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Old 12th Jan 2019, 12:58 am   #28
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Default Re: Trio 9R-59D receiver problems.

Apart from anything else, there is some crossover with Tony Duell's excellent restoration in success stories [still on the front page] despite the slide rule scales. It's taken a while to find out which type of set is involved here [p25*] and nearly all these topics have been covered in previous threads as well. Of course it's not the same as one to one tuition

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Old 12th Jan 2019, 10:40 am   #29
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Default Re: Trio 9R-59D receiver problems.

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Originally Posted by Station X View Post
Very good. There is a D suffix model then. I know that the circuits of the 9R-59DE and 9R-59DS are identical because at one time I had the user manuals for both sets and I compared the diagrams in the manuals.

I think the 9R-59D must use the same circuit.

There were some minor differences between sets. My DS model came with a wired up socket for a voltage stabilizer, but other sets had a vacant hole in the chassis.
This set has the extra valve fitted for the stabilisation of the power, normal set has 8 valves this one has 9 ,.Phil said it was nothing to do with the power for the receiver.
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Old 12th Jan 2019, 10:43 am   #30
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Default Re: Trio 9R-59D receiver problems.

Any way i was told by David one of the members on the forum in post 13 .It was to move the transformer under side . Well i have the transformer out and about to solder in new wires . The wire i have is solid inside .Would this be good to use ?

Last edited by Humptydumpty; 12th Jan 2019 at 11:00 am.
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Old 12th Jan 2019, 11:22 am   #31
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Default Re: Trio 9R-59D receiver problems.

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Originally Posted by Humptydumpty View Post
This set has the extra valve fitted for the stabilisation of the power, normal set has 8 valves this one has 9 ,.Phil said it was nothing to do with the power for the receiver.
No I didn't, Trev. If you look back at the numerous and lengthy explanatory PMs I sent you, you'll see that what I actually said on 9th January was:

"Re the hum, does it vary with the volume control or is it constant? Go back to an earlier message of mine and check the HT voltage. Have you got a multimeter? It could be the main smoothing cap causing the hum but check other things first. The 0A2 is only a neon stabilizer for the VFO and BFO stages and won’t cause hum."

It might also be helpful to reiterate the advice I gave you in a slightly later PM on 10th January:

"The AC mains goes into the primary winding on the left, and AC comes out of the HT secondary winding on the right. This winding is centre-tapped to chassis. At each end of the secondary winding it says "160" and that will be 160 volts AC. The next thing is that diodes D6 and D7 chop off the negative half of the AC waveform and leave you with positive-going pulses of DC, which pass into C42 (40uF) which is the reservoir capacitor. From this point onwards, everything on the HT side is DC.

HT current direct from C42 feeds the anode (pin 5) of the output valve V8 through the primary winding of the output transformer. This is the 200V voltage you need to check at pin 5 of V8. HT current then passes through R37, a 2.2k 8 watt smoothing resistor, then C40 smooths the HT supply even more, and this HT supply feeds the screen grid of the output valve V8, and the anode of the audio stage valve V7b, and the IF stages. There is a second HT supply, smoothed by R38 and C41, which feeds most of the other stages of the radio. Your stabilizer valve drops the HT voltage and holds it steady at 150 volts to supply the local oscillator and prevent frequency drift.

For now, just concentrate on understanding how the HT supply works and measure the voltage on pin 5 of V8."
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Last edited by Phil G4SPZ; 12th Jan 2019 at 11:28 am. Reason: Update
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Old 12th Jan 2019, 11:34 am   #32
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Default Re: Trio 9R-59D receiver problems.

According to post #24 a transformer has been removed and presumably disconnected. Regardless of whether it's the mains transformer or the output transformer there'll be no voltage on pin 5 until the transformer has been reconnected.

This is a clear case of trying to improve the set's performance without fixing any faults first.
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Old 12th Jan 2019, 12:05 pm   #33
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Default Re: Trio 9R-59D receiver problems.

Quote:
Originally Posted by Phil G4SPZ View Post
Quote:
Originally Posted by Humptydumpty View Post
This set has the extra valve fitted for the stabilisation of the power, normal set has 8 valves this one has 9 ,.Phil said it was nothing to do with the power for the receiver.
No I didn't, Trev. If you look back at the numerous and lengthy explanatory PMs I sent you, you'll see that what I actually said on 9th January was:

"Re the hum, does it vary with the volume control or is it constant? Go back to an earlier message of mine and check the HT voltage. Have you got a multimeter? It could be the main smoothing cap causing the hum but check other things first. The 0A2 is only a neon stabilizer for the VFO and BFO stages and won’t cause hum."

It might also be helpful to reiterate the advice I gave you in a slightly later PM on 10th January:

"The AC mains goes into the primary winding on the left, and AC comes out of the HT secondary winding on the right. This winding is centre-tapped to chassis. At each end of the secondary winding it says "160" and that will be 160 volts AC. The next thing is that diodes D6 and D7 chop off the negative half of the AC waveform and leave you with positive-going pulses of DC, which pass into C42 (40uF) which is the reservoir capacitor. From this point onwards, everything on the HT side is DC.

HT current direct from C42 feeds the anode (pin 5) of the output valve V8 through the primary winding of the output transformer. This is the 200V voltage you need to check at pin 5 of V8. HT current then passes through R37, a 2.2k 8 watt smoothing resistor, then C40 smooths the HT supply even more, and this HT supply feeds the screen grid of the output valve V8, and the anode of the audio stage valve V7b, and the IF stages. There is a second HT supply, smoothed by R38 and C41, which feeds most of the other stages of the radio. Your stabilizer valve drops the HT voltage and holds it steady at 150 volts to supply the local oscillator and prevent frequency drift.

For now, just concentrate on understanding how the HT supply works and measure the voltage on pin 5 of V8."
Phil i will fit the transformer back .And take it in to e service guy all your information is good but i dont understand 1/3 of it . I am lost .So i will askl the mod to close this post and mark it as solved . So as not to waste any more of members time .Its like walking a blind man [me] across the street .And thanks Trev
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Old 12th Jan 2019, 3:44 pm   #34
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Default Re: Trio 9R-59D receiver problems.

Closed as requested.
Perhaps you could come back to us with a brief explanation of what the service guy did to repair/restore the radio.
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Old 15th Jan 2019, 12:32 am   #35
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Default TRIO 9R- 59D Question

Going back to my old post i talked about the Trio 9R 59D that was in need of tlc .The problem was hum .And also a worn potentiometer . And G4SPZ explained what i must do to fix the noise . Even told me the right pot to order .It came in a few days only to find it was not exactly the right one .But after a little work on the pot, along with the front of the receiver exit hole it was a good replacment but a little small in diameter . . And now on to the next part . I was told by a good forum member to reposition the small transformer and fit it under the chassis .This was done .This move made no change and i still have this hum. I know very little in repair of such items .But i am going to stop this hum if i can before it and the FROG7 both go away for service . So now its back to this checking of the V8 pin5 that i was told about by Phil G4SPZ . After reading it over and over again i then realise i had been counting pin 5 clockwise . So after i checked it again its showing up a voltage of 220 volts dc. After reading the message from Phil his words were to check v8 pin 2 . Now this pin is only showing intermitant voltage like 0 volts up to 4 volts . Need more information on this to carry on the checking ., Thank you.
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Old 15th Jan 2019, 12:57 am   #36
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Default Re: Trio 9R-59D receiver problems.

V8 pin 2 is the cathode of the output valve. It should show a steady 6.5 VDC. If the reading fluctuates suspect the valve being loose in the valve holder or a problem with either the cathode resistor or its bypass capacitor.
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Old 15th Jan 2019, 10:04 am   #37
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Default Re: Trio 9R-59D receiver problems.

While you're at it check the voltage on V8 pin 1 the control grid. The DC voltage here should be close to zero.

ISTR that my own set was showing a positive voltage here as a result of the audio coupling capacitor from the previous stage being electrically leaky.

Please note that neither of the voltages we've discussed are likely to have anything to do with the level of mains hum. We're just checking for correct operation of the output stage.
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Old 15th Jan 2019, 10:44 am   #38
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Default Re: Trio 9R-59D receiver problems.

Station x Thats good to know .I will try and find capacitot andaldo resistor . I will return with what i find once i can locat both items Can you help me locate thes parts in the chassis .
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Old 15th Jan 2019, 10:57 am   #39
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Default Re: Trio 9R-59D receiver problems.

They'll be connected between pin 2 and the chassis. It'll be easy enough to measure the resistance of the resistor. However before you change anything check that the valve pins are clean and firmly gripped by the sockets in the valve holder.
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Old 15th Jan 2019, 11:24 am   #40
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Default Re: Trio 9R-59D receiver problems.

In post #13 I mentioned the series of articles in Radio Constructor, in 1970/’71, which included modifications to reduce hum. I stated: “I'm not suggesting that those modifications will cure an abnormally high level of hum in this particular set”. The reason I said that is that the articles were on how to improve the performance of a set which – back in 1970 - was almost new - not a set such as the one that is the subject of this post, now getting on for 50 years old.

In post #15, the O.P said "I'm out of my depth on electronics". When I see that, ordinarily, I cease to get further involved.

We've been here many times, (as often as not with Dansettes and the like), and we have to assume a minimum level of competence due to safety and competence concerns. I don't want to sound rude or unkind, but if someone doesn't know how to use a multi-meter to carry out live testing and to interpret the results, little progress can be made and the individual can be exposed to safety hazards. Reading the posts, it's still not evident to me whether voltage readings have been taken and compared with the circuit. In particular, with regard to the anode and cathode voltages on V8.

On a set of this age, the most likely cause of hum would I think be the three x 40uF reservoir/smoothing caps, but that would have to be determined not by speculation, but by a proper diagnosis, because in some instances, (notably the DAC90A), the hum can be from other causes associated with the output valve, and rarely from the reservoir/smoothing caps.

If this was my set, I'd start by checking if there is 160V AC at the input to D6 & D7 - the rectifier diodes? If yes, is there 200V DC at the output of the diodes? If not, the diodes are suspect. If there is 200V DC or thereabouts, is there 200V at the anode of V8, pin 5? and is there 6.5V at the cathode of V8, pin 2? Advice has been given to check those voltages, but it's not apparent to me with any certainty if the actual voltages have been established.

Is there any DC on the grid of V8 (pin1). If so, that is arriving via C34 - the audio coupling cap from the anode (pin 6) of V7 due to the cap being 'leaky' in the electrical sense. However, if C34 is a disc ceramic rather than paper capacitor, and there is no DC on pin 1 of V8, that's all to the good.

Unless the voltage conditions around V8 are close to the circuit, that would need to be resolved. I think it's unlikely that any of the valves are the source of hum. If V8 was removed and a signal tracer applied to pin 6 of V7 via a .01µF cap and hum was still present, that would tend to exonerate V8 and point to the reservoir/smoothing caps as the HT of both valves of course are via the common HT line.

Assuming that it's been confirmed there is 200V DC from the output of D6 & D7, my approach would be to temporarily substitute the reservoir/smoothing caps, of which there are three in a single can - all 40uF, the nearest modern value being 47uF caps. If that cured the fault, it would be up to the individual whether or not to leave C40, 41 and 42 disconnected and to fit replacements under the chassis, leaving the redundant can in place for appearance sake, or whether to disgorge the contents of the can and re-stuff it.

On the O.Ps own admission, he doesn't have the competence to carry out such tests and rectification work and I'm not suggesting that he does so as he is unable to locate components on the chassis by reference to the circuit diagram. I think it would be much better if some kind soul in his vicinity had a look at it with him. Clearly to entrust the work to someone on a commercial basis would cost way beyond what the set is worth.

These are just my own observations, others may take quite a different approach or may disagree. I really don't mind, and for the reasons stated, I'd prefer not to engage further in this thread.
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