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Old 20th Jan 2019, 8:02 pm   #101
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Default Re: Trio 9R-59D receiver problems.

Time to give in Graham i dont know which the R35 is .But a quick check on all resistors looking like the smallest of the three you posted to me all read zero power on and off.
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Old 20th Jan 2019, 8:44 pm   #102
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Default Re: Trio 9R-59D receiver problems.

Conflict on both diagrams one said its on the right other on the left .Had enought to- day packing it in for now.
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Old 20th Jan 2019, 8:50 pm   #103
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Default Re: Trio 9R-59D receiver problems.

Just measure from V8 pin 2 to chassis.
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Old 20th Jan 2019, 9:17 pm   #104
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Default Re: Trio 9R-59D receiver problems.

I'm looking at an online manufacturers service manual for the Trio 9R-59DE, the circuit ref for the output valves cathode bias resistor differs from the ref that's shown on the board layout, not that it should make much difference to the proceedings but I thought I'd point out the error anyways:

http://www.wb4hfn.com/KENWOOD/Manual...e%20manual.pdf

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Old 20th Jan 2019, 9:49 pm   #105
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Default Re: Trio 9R-59D receiver problems.

ms ,, thanks thats what i found and the value is the same along with markling under it but hard to read as it was covering the id up i find 300 ohm mark and K ,, thank god for that lol. .So Graham i will check it out as you ask with volts or resistance ?pin 2
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Old 20th Jan 2019, 10:05 pm   #106
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Default Re: Trio 9R-59D receiver problems.

There are only two components connected to pin 2 (cathode) of V8, namely, C37 and R35, which are in parallel with each other, with one end going to pin 2, the other, to chassis ('ground'). R35 should be 330 Ohms +/- 10%, so if it's between 297 Ohms and 363 Ohms it will be in spec. To check it, with the power off and the set unplugged from the mains, with your multi-meter on the Ohms range if you connect your meter prods as shown in the attached diagram, between pin 2 of V8 and the chassis, if it reads between 297 and 363 Ohms, it's OK. If not, change it with the one that Graham gave you.

There needs to be 6.5V or close to it from pin 2 and chassis. With your meter on the low DC Volts range and set switched on, (and V8 plugged into the socket), and the test prods at the same points as when you checked R35, there should be 6.5V DC. If so, all's fine.

It shouldn't be hard to find which R35 is - there are only two components (C37 & R35)connected to pin 2 of V8. If you're struggling with that, look at the PCB track from pin 2 of V8 and see where it goes. You've already changed C37, both ends of which go to R35. (As R35 is rated at 2 Watts, it might be a small wirewound resistor, looking a bit different from most others).

Incidentally, this is all about ensuring that V8 is working as it should be - it has no bearing on the excessive hum of course, which has yet to be resolved. (Likely culprits: C40/41/42?).

Hope that might rekindle your interest.
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Old 21st Jan 2019, 10:34 am   #107
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Default Re: Trio 9R-59D receiver problems.

Thanks David the voltage is 6.5 at pin 2 . Just setting up the meter to check ohms.
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Old 21st Jan 2019, 12:03 pm   #108
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Default Re: Trio 9R-59D receiver problems.

David the analog meter set on ohm x10 reads 30 on the scale

So x 10 ohm set on the meter and pointer is on 30 = 300 - 10 % is 300 = 270 + is 330 . Thats if i have done this right .
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Old 21st Jan 2019, 12:16 pm   #109
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Default Re: Trio 9R-59D receiver problems.

In post #86 you wrote:

Quote:
Originally Posted by Humptydumpty View Post
... looking at the schematic dia it looks like both 5 and 6 pins are on the same voltage 200DC voltage to run from v8 Just checked both pins again 5- 6 5 = 210 dcv 6 = 170 dcv .
Not that it has any relevance to your hum problem, for the sake of accuracy, the schematic does not in fact show that pins 5 & 6 are fed from the same point and on the same voltage. If you look again at the schematic, you will see that pin 5 is fed directly from the output of the two rectifier diodes, whereas pin 6 is fed from the output of R37, and thus, the voltage will be lower. Though the voltage of pin 6 isn't shown on the schematic, 170V seems about right.

In the attachment below I've highlighted the relevant part of the circuit, showing the HT path to pin 5 of V8 in red, and to pin 6 in blue.

Given that you now have 6.5V on pin 2 of V8, and apart from the excessive hum the set is working well enough, that suggests that the output stage is now working as it should.

Turning to the hum problem, as I said in post #40, I feel that the most likely source will be the reservoir and smoothing caps and Id reiterate that to investigate that further, my approach would be to temporarily substitute those 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 the triple can C40/41/42 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 to re-stuff it.

Its a matter for you whether you feel competent and confident enough to do these tests yourself, and if need be, to permanently replace the three caps in question.

Every good wish for a successful conclusion.
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Old 21st Jan 2019, 12:59 pm   #110
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Default Re: Trio 9R-59D receiver problems.

Thank you once again David. I will look at the part in question C41 -42 43 can ..And ponder on it to see if i can do it myself. But i might need help sorting the parts . Would be a big help if i knew where to pick up these caps from and what to ask for . I would think its impossible to get original part after all this time .
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Old 21st Jan 2019, 1:58 pm   #111
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Default Re: Trio 9R-59D receiver problems.

I kniow you put the three caps together,, and that all the three earths go tgether and the three positives go together on the base of the three caps,, but as to where they go in the receiver after i am lost .
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Old 21st Jan 2019, 2:59 pm   #112
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Default Re: Trio 9R-59D receiver problems.

Rephrase the above the 3 positives do not go together .
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Old 21st Jan 2019, 3:53 pm   #113
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Default Re: Trio 9R-59D receiver problems.

David this 40 uf is that the overall total , or 120 uf total uf of the can . On the can it reads 40-40-40 So is there any one that would rebuild these caps .I did a search when i started to work on the receiver to replace the cap , and i came up with nothing . Lots on youtube but not step by step on how it is done .
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Old 21st Jan 2019, 7:02 pm   #114
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Default Re: Trio 9R-59D receiver problems.

This is a picture of the cap It has 1 - 2- 3- 3 stamped in to each lug on the base of the cap, would both the conections with 3 stamps on them be 200volts each , No luck searching for a replacment cap . So it looks as if i will never get rid of this hum .The receiver is one of the best i have had for reception . .By the way i found a sorce of these bulbs .But they cost 10 for 2 inc postage .
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Old 21st Jan 2019, 9:10 pm   #115
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Default Re: Trio 9R-59D receiver problems.

Quote:
Originally Posted by Humptydumpty View Post
David this 40 uf is that the overall total , or 120 uf total uf of the can . On the can it reads 40-40-40 So is there any one that would rebuild these caps. I did a search when i started to work on the receiver to replace the cap , and i came up with nothing . Lots on youtube but not step by step on how it is done .
There are three separate capacitors in the can, which is why it states 40-40-40. We tend to call them 'smoothing capacitors' for shorthand, but the first one after the rectifier is strictly speaking, the 'reservoir' capacitor. On your set, they are C40, C41 & C42. I've highlighted them on the clip of the circuit below.

The role of the reservoir capacitor is to smooth out the ripple that remains after the AC voltage has been rectified. The smoothing capacitor(s) provide additional smoothing. If the capacitors deteriorate over time, as they do, they fail to reduce the ripple. In a half-wave rectified power supply this presents as 50 Hz hum, and in a full wave rectified supply, as 100Hz hum.

It might help you to understand how smoothing circuits work if you look at the sketches below, which cover half-wave and full wave rectification.

To check if the three capacitors in the can are causing the hum, it would be necessary to disconnect the positive connection(s) of each section in turn and to temporarily wire a replacement capacitor, (which would need to 47F as 40 F is an obsolete value), from the wires that were connected to the positive tag of the original can, and ground. If that does indeed cure the hum (remembering that in any event, the 9R59DS is noted for some background hum), then it would be a choice of either permanently and safely wiring the three external capacitors under the chassis, leaving the can disconnected but in place, though more experienced restorers (rather than 'repairers'), might opt to open the can, remove the contents, fit three compact capacitors in the can and re-seal it. Any replacements will need to have at least the same working voltage as the originals.

The last picture shows examples of modern compact capacitors with adequate ripple ratings, which will fit side by side inside typical smoothing cans.

You've done well to get as far as you have with the support of others, but without wishing to sound unkind, I don't think you have the competence or experience to safely undertake any of the tests or repairs on the power supply and would be better advised to entrust the work to someone else - for example from the 'Services Offered' section of the forum - (or maybe attend one of the 'workshops' that are arranged from time to time by various individuals). The work involves some live testing, an ability to understand how the circuit relates to the components on the chassis, and an awareness that even when a set is disconnected from the mains, high voltage smoothing capacitors, if not discharged, can hold a charge for some time and cause nasty shocks to the unwary.

I think that's as much help and advice as I feel able to give.
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Old 22nd Jan 2019, 10:26 am   #116
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Default Re: Trio 9R-59D receiver problems.

David i understand ,And i can see on yioutube how its done to pack three caps into the one can .Once i have a c40 -41- 42 cap i can remove the old one and replace it .I think that part i can do. And i can check the old one before i remove it for build up of voltage .I have read some place that there is the way to discharge them before you remove . Must search for the right way to ft the caps in the can. So i would need 3 x 47 uf 250v thats the easy part .Thank you David .Looks like the boat stops here for now . Strange to say but untill i came on the forum i knew nothing about my multi meter ot my analog meter .Now i can use them .And both of them are over 5 years old and never used till this repair on the Trio. I will look in services section as you said .
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Old 22nd Jan 2019, 12:02 pm   #117
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Default Re: Trio 9R-59D receiver problems.

Is it possible to remove C40 41 42 from another receiver and fix it in place ?
To-day i have just had another delivered .Its rough outside, and the case shows signs of surface rust along with the front face the paint is pitting on the edge of the dial openings .Bit inside looks good . I will fire it up and if its not up to much it will end up as spares. It all looks intact and the valve shields are on .Mine are missing .So later on i need to try it out .Watch this space .
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Old 22nd Jan 2019, 1:06 pm   #118
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Default Re: Trio 9R-59D receiver problems.

As to discharging the capacitors, lots of people will just put the blade of an insulated screwdriver across the live and neutral terminals, but it's much safer and more sensible, especially for the inexperienced, to make a simple discharge tool consisting of two insulated leads with a resistor in series, (typically 20K 5 Watt), so the charge decays away over a few seconds, rather than with a sudden crack and a flash. EG:

https://www.ifixit.com/Guide/Constru...arge+Tool/2177

The charge on the capacitors may have in any event decayed if the set's not been switched on for some hours or days, but it's always best to be on the safe side.

If you do decide to do the work yourself, before you think about re-stuffing the can, it would make sense for you to disconnect the three red wires and connect the + lead of each new capacitor to each of those three red wires, with the negative leads of the three new capacitors to the chassis. If that does cure the hum, I think you'd be wise to wire the new caps permanently and safely beneath the chassis, leaving the old can in place as I've mentioned before as an option. Opening up the can, removing the contents, resealing it and re-fixing it might be a step too far, but what you do with the set is a matter for you - as the saying goes, "you ride at your own risk" and on that, I've already sounded a note of caution as to potential hazards when working on the power supply. I'd draw your attention to the disclaimer at the bottom of the Forum page.

Suitable miniature Rubycon capacitors can be obtained from Farnell.

47uF 400V rated ones are 12.5mm diam x 30mm tall. They're 105 degrees rated, have a more than adequate ripple rating and long life, with a stated life of 7,000 - 12,000Hrs. They'd easily fit permanently under the chassis, but you should of course insulate the positive leads where they join the existing red wires, and the caps mustn't be left just dangling. (They would also fit inside the can).

https://uk.farnell.com/rubycon/400tx...831328?st=47uF Rubycon capacitors

The datasheet of this range of capacitors is here:

http://www.farnell.com/datasheets/23...025.1497772082

Hope that helps.
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Old 22nd Jan 2019, 2:56 pm   #119
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Default Re: Trio 9R-59D receiver problems.

I agree that you should leave the original three in one capacitor can in place and fit replacements (if necessary) under the chassis.

I think you should definitely NOT attempt to re-stuff the original capacitor can!

For cheapness you could just buy one single 47uf @ 400 volts working replacement capacitor and fit it in place of each of the three in turn and see if it's just one that's causing the problem, starting with the one nearest the rectifier which is the reservoir.

You say you couldn't find replacements - there must be dozens of places selling them!

Cricklewoods in London do a 47uf @ I think 450 volts with good ripple current rating for a couple or three quid - plus the dreaded postage of course. Phone them with your bank card details and order one if you don't do Paypal.

Just found the Cricklewood capacitor, link below:-
https://www.cricklewoodelectronics.com/47A450.html

If you do replacements under the chassis, you could just fit them roughly for a start to see if it cures the fault and if it does, you can then decide to make a better job of fitting them later. If it makes no difference, then just connect back up to the original can and look elsewhere.
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Old 22nd Jan 2019, 5:40 pm   #120
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Default Re: Trio 9R-59D receiver problems.

For the sake of completeness, I ought to say that new multi-section electrolytic capacitors, which would be a direct replacement, are available from specialist suppliers but at a price that would be more than the value of the set. EG, triple 40F 525V twist lock fitting $40.90 US plus shipping: https://www.tubesandmore.com/product...-525v-404040uf

There might well be other sources a little cheaper within mainland Europe, but those from Farnell or Cricklewood will do the job just as well, at more realistic prices.
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