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Old 21st Mar 2023, 3:48 pm   #1
Featherfoot
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Default Transformer for Goodmans 110

Hello everyone. Vintage newbie here. I’ve just finished recapping the 110 and after getting some odd readings I want to replace the mains transformer. Unfortunately, I haven’t a clue as to what to replace it with. There are no markings of any kind and looking at the parts list on this site it has no ratings. My electronics knowledge is basic so I don’t know what VA or voltage values are applicable so if anyone can inform me and maybe some good brands I’d be very grateful. Thanks in advance.
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Old 21st Mar 2023, 3:57 pm   #2
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Default Re: Transformer for Goodmans 110

Why do you think the mains transformer needs replacing? What "odd readings" are you getting?
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Old 21st Mar 2023, 6:35 pm   #3
Ted Kendall
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Default Re: Transformer for Goodmans 110

I fear we've been here before - a thread which begins "I recapped it and now it doesn't work". Blanket re-caps of semiconductor kit are seldom necessary and not to be undertaken without good reason, whatever the Facebook gurus say. The risk of inducing faults through errors, such as poor soldering or reversing electrolytics, is quite large. I'd put money on your mains transformer being OK - I'd go back and check your work before pursuing this further.
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Old 21st Mar 2023, 7:14 pm   #4
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Default Re: Transformer for Goodmans 110

Good advice Ted, though these things are probably full of Callins
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Old 22nd Mar 2023, 12:41 am   #5
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Default Re: Transformer for Goodmans 110

Fair point, Nick. It's just this cult of diving in regardless on the assumption that a recap is a magic bullet which is doing more harm than good. To be fair, I've got something on the bench at the moment where shotgunning is the best policy - a Casio DAT using the Mitsubishi transport which is chock full of leaky surface mount caps. That's forty caps before you even start troubleshooting - taxing on both iron and patience!
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Old 22nd Mar 2023, 4:55 am   #6
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Default Re: Transformer for Goodmans 110

The first thing I would want to know is – are the scale and meter lamps alight?

If they are and the unit is "dead", making a loud humming noise, distorted or very low volume either or both channels I very strongly recommend the OP entrusts the repair of this to another experienced Forum Member with the skill and experience to work on these, using the Repair and Restoration services required" thread!

If the scale and meter lamps are out, there could still be a fault present that could cause further damage, both to the original transformer which will almost certainly be OK, or even possibly the PCB itself if there's an internal short present!

I am not going to advise the OP on repairing this further – Goodmans 110s use direct–coupled amplifiers throughout and unskilled investigation can damage most of the transistors, and as Ted Kendall said, this Facebook nonsense of "recapping" has caused more harm than good in so many tales on here in the past!

(I myself have found that repairing old circuits often needs electrolytic capacitors of similar vintage, value, voltage rating and size to work successfully, and they need to be chosen by an experienced engineer with the knowledge to test them, and it is seldom necessary to replace more than one or two!)

I recommend the OP asks for help using the "Repair and Restoration Services" Required section!

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Last edited by Chris55000; 22nd Mar 2023 at 5:21 am.
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Old 22nd Mar 2023, 8:40 am   #7
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Default Re: Transformer for Goodmans 110

Having restored about five Goodmans 110 receivers in recent years I have not had a single problem with mains transformers, nor any PCB mounted electrolytics. The faults being blown mains RF suppression caps, many grossly unclean switch contacts, faulty dial lamps, stiff tuning caps, and a few dry joints. Unless you've blown it somehow - and I think that would have been fairly obvious if you had - I would not put money on the mains trannie being blown. Service data is readily available via a Google search, I suggest you get it if you don't already have it and start by checking the voltages around the power supply and rails. We'll help you through that.
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Old 22nd Mar 2023, 5:03 pm   #8
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Default Re: Transformer for Goodmans 110

Thanks everyone. It’s mainly the power supply caps that I’ve changed. Two Nichicon super throughs for the reservoirs and five Nichicon KZ’s. It’s working perfectly and sounds dramatically better than before. I am an ex pro recording engineer and I trust my ear. The odd reading from the transformer is a resistance reading from the secondary winding to the core which (I believe) should be OL but isn’t. The other cap replaced is C133 in the tone circuit. Initially I changed it to a Nichicon KZ (22uf 50v) but I preferred the original Roderstein and have replaced that with a NOS I found in Germany. So I guess my question is still why am I getting that reading from the transformer?
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Old 22nd Mar 2023, 5:41 pm   #9
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Default Re: Transformer for Goodmans 110

What resistance are you reading?
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Old 22nd Mar 2023, 6:10 pm   #10
Ted Kendall
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Default Re: Transformer for Goodmans 110

Are you reading resistance with the transformer in circuit? If so, any number of paths may exist between a secondary winding and the transformer core, which is (or should be) connected to chassis. The likelihood is that all is well with it, if the set is otherwise working.
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Old 22nd Mar 2023, 7:59 pm   #11
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Default Re: Transformer for Goodmans 110

Leakiness in a bad way would probably trip your RCD, assuming you have one.
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Old 23rd Mar 2023, 4:03 pm   #12
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Default Re: Transformer for Goodmans 110

No, I removed the transformer to take readings that’s why I thought it was odd. In the Pro Audio world the transformers used affect the tonal quality of the amp or desk etc. and I’m assuming its the same in hi-fi. But that’s why I’m here - to learn from people who know better than I. I am not an electronics engineer but learned to solder and read a scope as a teenager in my first job working on mixing desks. Only the very early 110’s used Callins and only two of them. They usually have blown their plastic (?) casings off and dried out. So the opinion that the tranny would seem to be ok is good enough for me and another job I don’t have to do.
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Old 23rd Mar 2023, 4:32 pm   #13
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Default Re: Transformer for Goodmans 110

Please see post #9.
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Old 23rd Mar 2023, 11:52 pm   #14
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Default Re: Transformer for Goodmans 110

Does the mains transformer have a Screen wire/connection?
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Old 26th Mar 2023, 1:48 am   #15
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Default Re: Transformer for Goodmans 110

Not on any of the Goodmans and similar circuits I've seen!

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Old 29th Mar 2023, 10:25 am   #16
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Default Re: Transformer for Goodmans 110

Thanks for everyone’s advice. I’m actually eyeing another 110. Mine is the White version with the coloured buttons. You could probably make a convincing copy from Lego bricks. So the one I’m looking at has ‘distortion in both channels’. My idea is to spray the teak case black so I have positive and negative versions. It’s only £20 and is in very good cosmetic order. Fault finding the distortion is beyond my limited ability so if anyone could point me in the direction of anyone wanting to undertake the work, I would be very grateful.
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Old 29th Mar 2023, 12:14 pm   #17
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Default Re: Transformer for Goodmans 110

I'm obviously not going to get an answer to the question asked in post #9.

Thread started with "odd readings" on the mains transformer, but we still don't know the actual value measured.
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Old 29th Mar 2023, 4:45 pm   #18
Featherfoot
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Default Re: Transformer for Goodmans 110

Apologies for not replying to post #9. The opinion that the Tranny was not faulty is good for me and it’s back in the receiver and working as normal. As I said, I’m not an electronics engineer so I guess I don’t have a burning desire to know the readings. Except that in the back of my mind There is the nag that it isn’t as good as it might be !
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