15th Sep 2020, 3:03 pm | #21 |
Nonode
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Re: Bush AC41
Yes same circuit but the Bush circuit shows the dial lamp winding, thought it might be helpful to see it.
John |
15th Sep 2020, 3:06 pm | #22 |
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Re: Bush AC41
Should have said shows dial lamp winding more clearly.
John |
15th Sep 2020, 3:13 pm | #23 |
Octode
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Re: Bush AC41
I've replaced the flex, but I think I should gather some capacitors and replace all of the decoupling capacitors. I've got some film caps, but not every value I need, so I'll try to get an order in.
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15th Sep 2020, 3:14 pm | #24 |
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Re: Bush AC41
That reminds me, it's been gotten at in the past, someone has had the lamps.
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15th Sep 2020, 4:02 pm | #25 |
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Re: Bush AC41
What do you think the options are if necessary, for that metal cased two in one 32uF cap? I can only think, leave it in place and put two replacements underneath inside the chassis of the radio.
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15th Sep 2020, 4:16 pm | #26 |
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Re: Bush AC41
Occasionally you'll see these dual cans come up on eBay, but buying a used electrolytic is a case of buyer beware because you don't know its history or if or how it has been tested. Some people use Chinese capacitance testers on them but even if they show reasonable capacitance value they can leak dc like a sieve when you put 250v+ on them. Personally I do exactly what you have said - disconnect the twin can leaving it physically in place (unless it is oozing gunk), and strap axial (if available) replacements underneath. The more enthusiastic seek out radial replacements that are small enough, then scrape out the innards of the old can and stuff the 2 radials inside. Do be careful with your eyes if you do this as I recently (unusually for me) restuffed an 8uF electrolytic on an Eddystone 750 and when I pierced the seal the blighter erupted a jet of fluid at me. Cheers, Jerry
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15th Sep 2020, 9:08 pm | #27 |
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Re: Bush AC41
I would agree with Jerry, I have used the different options, worth taking a look at Cricklewood Electronics, they have some suitable capacitors.
John |
15th Sep 2020, 9:55 pm | #28 |
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Re: Bush AC41
Half an hour of your time and no one but you will know it's not original.
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16th Sep 2020, 10:29 pm | #29 |
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Re: Bush AC41
Has anyone ever noticed that the trader sheet has different numbering and/or values for some of the capacitors compared with the separate schematic available?
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17th Sep 2020, 9:03 am | #30 |
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Re: Bush AC41
Different component designations in Trader sheets when compared to manufacturer's service sheets is almost universal. That's why when talking someone through a repair it's essential that you're both singing from the same hymn sheet.
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17th Sep 2020, 1:44 pm | #31 |
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Re: Bush AC41
Try Changing all the waxies, a set this age will need those changed, but if it was me I would also replace the main smoothing cap and any other electrolyics
Ken |
17th Sep 2020, 3:40 pm | #32 |
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Re: Bush AC41
Yes, noted. I intend to replace all the waxies and electrolytics, but I'll not touch the tuned circuits at this point, if at all.
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23rd Sep 2020, 12:21 pm | #33 |
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Re: Bush AC41
I've got some replacement caps. Whilst delving deeper, I found this under the rectifier valve. The valve looks ok, perhaps the previous rectifier went pop?
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23rd Sep 2020, 12:52 pm | #34 |
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Re: Bush AC41
This just looks like soot from a high dissipation resistor ,ie the wire wound.My only other thought is,I notice fresh soldering? Or,it looks pretty clean on one joint.
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23rd Sep 2020, 1:34 pm | #35 |
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Re: Bush AC41
Just general dirt and muck from heat generated by the valves and that big wirewound etc. The rectifier runs hot so not unusual for this deposit. See it in a lot of valve radios. Nothing to worry about.
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23rd Sep 2020, 2:11 pm | #36 |
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Re: Bush AC41
Thanks chaps. Well I'm back in the lab with some coffee, so I'll get started and see where I get.
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30th Sep 2020, 5:15 pm | #37 |
Octode
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Re: Bush AC41
So, most capacitors replaced, leaving tuned circuits well alone.
Powered up, scoped the output of the rectifier, nice DC. It's very quiet, nothing heard at all. The occasional note heard when turning the tuning dial.....
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30th Sep 2020, 5:53 pm | #38 |
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Re: Bush AC41
Time for some voltage checks,starting with the HT.
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30th Sep 2020, 6:46 pm | #39 |
Octode
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Re: Bush AC41
Well the HT from the rectifier sits at around 250v. I'll need to get some test voltages for other areas.
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30th Sep 2020, 9:29 pm | #40 |
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Re: Bush AC41
Good idea to compare measured anode, & grid 2 (screen) voltages against those quoted in the service data. These will tell you something about how the valve is performing, together with the total current it is passing calculated by measuring the cathode voltage divided by the measured value of the cathode resistor. Also do you hear a buzz from the speaker when touching the volume control slider ( with volume turned up, obviously) via a screwdriver blade? Cheers, Jerry
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