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Old 14th Feb 2019, 11:21 am   #61
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Default Re: Capacitors for Trio 9R 59D

I gave detailed instructions as to how to check the voltage on the rectifiers in post #57

You could in addition do a diode test (power off) as described in post #1 in this thread:-

https://www.vintage-radio.net/forum/...ad.php?t=42194
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Old 14th Feb 2019, 11:57 am   #62
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Default Re: Capacitors for Trio 9R 59D

SX what is [wrt] ?
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Old 14th Feb 2019, 12:02 pm   #63
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Default Re: Capacitors for Trio 9R 59D

with respect to. It means you connect the negative lead of your meter to the chassis.
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Old 14th Feb 2019, 12:15 pm   #64
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Default Re: Capacitors for Trio 9R 59D

Well thats a new one . i would have understood [nlc] but its in your understanding .I will do the first step and check the ac voltage on the transformer side of both transistors or risistor . Back later have a rest .
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Old 14th Feb 2019, 12:48 pm   #65
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Default Re: Capacitors for Trio 9R 59D

I really think that the question now is should YOU carry on HD? [post 56]. Not "we" ie David.... who has probably gone for lie down after all his efforts. You don't seem very happy in your task or with the radio itself now. It's not very difficult to answer most of these questions yourself, especially if it's just identifying a component like a rectifier The normal process is doing some work and asking questions only when really stuck. Unfortunately you seem to have been stuck with nearly everything so far, -and repeatedly-is this hobby really for you

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Old 14th Feb 2019, 1:02 pm   #66
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Default Re: Capacitors for Trio 9R 59D

Hi there all you young whipper snappers, you will have to pedal quite fast to catch up with me. !!

One reason for excessive hum is if the rectification is half wave rather than full wave. This could happen if a diode or one section of the transformer is open circuit.

Without power, measure the resistance (forward voltage) of the diodes, they should show 0.6 or so in the forward direction and open circuit in the reverse direction. Disconnect one end then :-

Measure the resistance of both 160V windings. If one is open circuit, then you can either get the transformer rewound (expensive) or bodge it by adding a couple of extra diodes to make a bridge rectifier and use the good winding.
A scope would soon determine if you were getting 50 or 100Hz ripple but presumably you do not have such. I have one which I have not used for many months so not really necessary.

Go to your local radio club or repair cafe and get some personal help. It is all very logical and with one good set to compare, should be possible.
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Old 14th Feb 2019, 1:05 pm   #67
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Default Re: Capacitors for Trio 9R 59D

Quote:
Originally Posted by Humptydumpty View Post
Well thats a new one . i would have understood [nlc] but its in your understanding .I will do the first step and check the ac voltage on the transformer side of both transistors or risistor . Back later have a rest .
I would just like to point out that there are no transistors in this set. It's the diodes aka rectifiers you need to check the voltages on.
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Old 14th Feb 2019, 1:17 pm   #68
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Default Re: Capacitors for Trio 9R 59D

Got it but it said they work on same idea in early post .
Loking in the bottom of the chassis i see both the rectifiers are on their own taps from the transformer both at 160v i thought they would be joinedr together end to end .
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Old 14th Feb 2019, 1:20 pm   #69
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Default Re: Capacitors for Trio 9R 59D

To understand why the rectifiers are wired the way they are you'll need to read up about half-wave and full-wave rectification circuits.

Forget that for the moment though. Do the tests and post the results for analysis.
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Old 14th Feb 2019, 1:56 pm   #70
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Default Re: Capacitors for Trio 9R 59D

First part i find 160v ac . On both of them . See pictire
Need to understand the next step .Only used old meter i need to sort out how to use the new one now.
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Old 14th Feb 2019, 2:18 pm   #71
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Default Re: Capacitors for Trio 9R 59D

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Originally Posted by Humptydumpty View Post
G4EBT Dave now you tell me about the rectifier ,what is a rectifier and i will check it .And yes i did have a new meter . But i have not used it as yet .
But we are off again on another tangent . Do you think we should carry on ?
You may be going off at a tangent - I'm not. I've said time and again that you should check the voltages and compare them to the circuit. A normal logical diagnostic approach with any set would be to do that, and to note any discrepancies, yet you now say "you've got a new meter but haven't used it yet".

Huh? I explained that the 'long thin blue thing that gets hot', is R37. I explained how to use your meter to check the resistance of R37, how to check the Voltage drop across it, and how to calculate the Wattage being dissipated by dividing the resistance into the Voltage. You clearly haven't done that, nor any other Voltage checks.

I mentioned the rectifiers because good place to start making Voltage tests is with the power supply, because if that isn't functioning correctly, none of the Voltages around the set will be correct. Maye I'm taking too much for granted in assuming that you'd know that the job of a rectifier is to rectify the AC current from the mains transformer output into DC. Sometimes solid state and selenium rectifiers can fail over time (as can valved rectifiers of course but not relevant here). Hence, as a starting point, it would be normal to check the AC input to the rectifiers (D6 & D7 on your set) and the DC output from the rectifiers with the meter set to DC Volts.

As shown on the attached clip of the circuit.

I've explained several times that you need to study the circuit, then identify the actual components you need to check. If you took note of that advice, you wouldn't have been asking what the 'long hot thing' was (R37) or what the rectifier was, because you'd see that D6 & D7 inputs are connected to the mains transformer secondary. D6 has C43 across it with the output is connected to R37. D7 has C44 across it, and it's output is connected to R38 (1K 4 Watts). Both D6 & D7 are connected to C42 (40F).

To answer your rhetorical question 'do we think we should carry on?'

Well considering that I've urged you to carry out voltage and current tests, and though you have a meter but haven't used it, and considering that I've urged you to look at the circuit and relate it to the actual components, but you say 'a lot of it goes over your head', I see little point in my carrying on because my powers of persuasion seem totally inadequate, so I think I'll head for the exit.

There are lots of excellent books on vintage radio restoration, and on how to use a multi-meter.

Every good wish in sorting the set Trev, though you did say you were going to sell them, in which case everyone's time and effort has been wasted.
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Old 14th Feb 2019, 2:27 pm   #72
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Default Re: Capacitors for Trio 9R 59D

The OP does now seem to have taken AC voltage readings at the input to the rectifier. His moving coil meter is perfectly adequate for the job, although it's not obvious what meter range he's using. I assume it's 300VAC?

As for the new auto-ranging meter it no doubt has a comprehensive user manual showing how to take AC and DC voltage measurements? The 300UP DC range on his m/c meter would be perfectly good for checking the DC side of the rectifiers though.
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Old 14th Feb 2019, 2:56 pm   #73
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Default Re: Capacitors for Trio 9R 59D

Diont bother any more i have had enough, i think you all have . If its this way, then dont post any more to help me ... Its good to talk about things you know all about,.But to me that knows nothing about the inside or receivers its hard . Thanks for each and everyone that got me to where i am . I moved transformer [out put] replaced potentiometers both sets . Replaced the caps .

Malcome please close thuis post down, no further request from me, for us to carry on . I will fit the covers on the Trio and put it away . You know i had a problem in 2000 i ended up with a auto neurone disease where as the muscles refuse to operate, ie eye lids arms and any part of the body with a muscle , [ but not down there ] ,. .
Years ago i was a foreman over 200 women and a large press shop .Worked up from a press operator to a press shop foreman .Thinking back i dont know how i got to this possition. . I do know now, it would not be able to do one half of what i did back then.
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