That's great advice and so thanks again. Although the 'expert' I used stated that it was the transformer, to be honest, I lost all confidence with him and will check that out first.
As it happens, and if the fault is with the transformer, I do have a second Ferrograph F307 amp that I bought second hand a few years ago that actually works. I could just take the transformer out of that and swap it over. "Well, why didn't you say that at the beginning!" I hear you ask. Good point. Somewhat stupidly maybe I am very sentimental about the original one bought when I was a student and been with me ever since. Comes with a lot of good memories and I would like to have kept it as original as possible. Because of cost and other reasons that now looks to be not possible. One way or the other it will work again - I will make sure of that.
One other query - it has all the original electrolytic capacitors. None of them seem to have leaked but should I be considering replacing them?
Many thanks again for all your help and advice.
As it happens, and if the fault is with the transformer, I do have a second Ferrograph F307 amp that I bought second hand a few years ago that actually works. I could just take the transformer out of that and swap it over. "Well, why didn't you say that at the beginning!" I hear you ask. Good point. Somewhat stupidly maybe I am very sentimental about the original one bought when I was a student and been with me ever since. Comes with a lot of good memories and I would like to have kept it as original as possible. Because of cost and other reasons that now looks to be not possible. One way or the other it will work again - I will make sure of that.
One other query - it has all the original electrolytic capacitors. None of them seem to have leaked but should I be considering replacing them?
Many thanks again for all your help and advice.
With the second unit available you certainly could confirm the unloaded voltages, and determine exactly which secondary option to order for the replacements. If you do decide to something with it.
I’d probably only re-cap if I suspected a problem.
I’d probably only re-cap if I suspected a problem.
Use a dim bulb tester to protect the second transformer.
Or the same fault may cause failure in the spare as well.
US$ 75 is 6000 Rupees, I could buy several 200VA E-I transformers for that much.
It is the quality and shipping which is the expensive part.
Or the same fault may cause failure in the spare as well.
US$ 75 is 6000 Rupees, I could buy several 200VA E-I transformers for that much.
It is the quality and shipping which is the expensive part.
Cheers to both of you. Yes - putting a filament lamp in series when testing the 'good' transformer seems like a very good idea. Thanks for the advice on re-cap. All look good so will leave well alone. Ferrograph were known for their quality and I guess that goes for the components they sourced as well It's just they're getting on for half a century old..................
Since you're in the UK, I'd strongly advise you to put in a query on the UK Vintage Radio Repair and Restoration forum. Some one there may have one you could negotiate for, and there are also people on there who will rewind transformers to a high standard. Either way you will probably get loads of tips and information in a UK context from them.
Mike
Hi Mike and thank you for your advice.
A progress update - I de-soldered all the connections and removed the 'faulty' transformer. I then checked the resistance on the primary windings. There are inputs for 240/220/117 volts. I have always had the voltage selector set to 240V when operating the amp. I believe K mains is actually around 230V. I got the following resistance.
My next job is to check the secondary windings to see what their resistance is - I haven't done that as I am now on a business trip for a few days - top priority when I get home.
Thanks for your suggestion to contact UK Vintage Radio Repair and Restoration forum - I have looked at their website and wondered if it was worth a shot. I will gest a bit more info and then go for it.
Thanks again for you advice - much appreciated.
A progress update - I de-soldered all the connections and removed the 'faulty' transformer. I then checked the resistance on the primary windings. There are inputs for 240/220/117 volts. I have always had the voltage selector set to 240V when operating the amp. I believe K mains is actually around 230V. I got the following resistance.
I thought they looked a bit on the low side but a friend I have been talking to said he thought that these looked about right. Any thoughts on that gratefully received!
My next job is to check the secondary windings to see what their resistance is - I haven't done that as I am now on a business trip for a few days - top priority when I get home.
Thanks for your suggestion to contact UK Vintage Radio Repair and Restoration forum - I have looked at their website and wondered if it was worth a shot. I will gest a bit more info and then go for it.
Thanks again for you advice - much appreciated.
How time flies! I have at last got back to trying to sort out my Ferrograph F307. Circuit diagram attached. Having removed the transformer and tested it it's all good. So a friend has suggested I check for shorts across C704 and C705 and transistors VT500 and VT502 on each channel. The capacitors were fine but I am not so sure I am getting the readings I should on the transistors. However, I don't really have the best test equipment and to be honest was thinking that replacement might be better anyway. I have read it's best to replace all four at the same time.
Problem - the NPN 16020 seems to be no longer available. Does anyone know what would be the nearest equivalent that can still be purchased
Problem - the NPN 16020 seems to be no longer available. Does anyone know what would be the nearest equivalent that can still be purchased