Sub Sonic Posted June 29, 2015 Posted June 29, 2015 Hi all, A while ago I started doing my first recap of an amp, and ordered the parts. Partway through, I realised that some of the caps were non polarised. I completed the work on the polarised caps including the main filter caps. I now want to order the remaining NP caps. Can anyone recommend a decent type to me, preferably available from RS Components? Caps are 4.7u 35V (2 off) and 100u 16V (4 off). I'm not sure what these caps do in the circuit, so to be safe I should probably just order decent ones. They are few in number and small, so cost shouldn't be an issue. Pics are coming I do have a circuit diagram somewhere that a member emailed to me, if I can find it. Cheers! SS
Sub Sonic Posted June 29, 2015 Author Posted June 29, 2015 (edited) I believe the section in the yellow box is to do with the protection relay, the rest of the board is essentially identical with it's opposite number, with just a few components reoriented. The amp obviously is dual mono.Cheers! Edited June 29, 2015 by Sub Sonic
pete_mac Posted June 29, 2015 Posted June 29, 2015 I'd ordinarily use Nichicon MUSE bipolar (the green ones) or Panasonic SU series, but the MUSE are not sold by RS and the SU series comes in packs of 100! The Nichicon EP 4.7uf 50v should do the trick: http://au.rs-online.com/web/p/aluminium-capacitors/5232707/ I can't find any 100uf bipolar caps on RS in sane quantities.
Sub Sonic Posted June 29, 2015 Author Posted June 29, 2015 Thanks @@pete_mac, that was fast! What would you recommend if we included E14 into the supplier options? Cheers! SS
Sub Sonic Posted June 29, 2015 Author Posted June 29, 2015 I like that amp, nice layout and duel mono Yes, it is so easy to work on it's not funny. 5 screws gets the top and bottom panels off and gives full access to all main board components :-)
pete_mac Posted June 29, 2015 Posted June 29, 2015 Thanks @@pete_mac, that was fast! What would you recommend if we included E14 into the supplier options? Cheers! SS I bought a bunch of Multicomp bipolars recently as some of them are at close-out pricing: http://au.element14.com/multicomp/mcnp63v475m6-3x11/cap-alu-elec-4-7uf-63v-rad/dp/1236679 http://au.element14.com/multicomp/mcnp35v107m10x16/cap-alu-elec-100uf-35v-rad/dp/1236673 Otherwise: http://au.element14.com/panasonic-electronic-components/ecea1hn4r7u/cap-alu-elec-4-7uf-50v-rad/dp/9696628 http://au.element14.com/panasonic-electronic-components/ecea1hn101u/cap-alu-elec-100uf-50v-rad/dp/9696660 1
Zaphod Beeblebrox Posted June 29, 2015 Posted June 29, 2015 Use plastic film caps for the 4.7uF (WIMAs, maybe) as they appear to be coupling caps. The larger bi-polars are probably used within the protection system, so anything will do. 1
Sub Sonic Posted June 29, 2015 Author Posted June 29, 2015 Thanks again @@pete_mac and @@Zaphod Beeblebrox. Would this be a suitable candidate for the 4.7uF? It does appear to be a coupling cap, it is at the signal input of the amp, along with a resistor or two. http://au.rs-online.com/web/p/polyester-film-capacitors/1083034/ Cheers! SS
Zaphod Beeblebrox Posted June 29, 2015 Posted June 29, 2015 Thanks again @@pete_mac and @@Zaphod Beeblebrox. Would this be a suitable candidate for the 4.7uF? It does appear to be a coupling cap, it is at the signal input of the amp, along with a resistor or two. http://au.rs-online.com/web/p/polyester-film-capacitors/1083034/ Cheers! SS Should do the trick. Check X-on for similar components at good prices.
pete_mac Posted June 29, 2015 Posted June 29, 2015 (edited) Ah, if it's indeed an input cap, get that electrolytic out of there! I'd use a Panasonic polyprop in that location. Whilst it has a wide lead spacing, you may be able to shoe-horn it in there as the Panasonics do have long leads: http://au.rs-online.com/web/p/polypropylene-film-capacitors/7270199/ They are 1 off order quantities too, so despite being more expensive per unit, it is cheaper than buying 5 of the WIMAs. Some of the WIMAs have short leads, which makes fitting polys tricky when the original electros are 5mm lead pitch. Edited June 29, 2015 by pete_mac 1
Sub Sonic Posted June 29, 2015 Author Posted June 29, 2015 Thanks for that ZB and PM. I just had a brain wave and had a look at some old amp boards I have. I have enough of the blue 1uF MKP (24 off) caps to make up to the values needed for the coupling caps, are they suitable? I also have a few of the red .47 MKC caps (16 off) but not quite enough to add up to the required amount. Cheers! SS 1
Zaphod Beeblebrox Posted June 29, 2015 Posted June 29, 2015 Using so many caps can lead to problems. Best to use a single cap in this application. 1
Sub Sonic Posted June 29, 2015 Author Posted June 29, 2015 Thanks ZB. Would bypassing an electro input cap with any of the above be of any tangible benefit in a vintage amp like this?
Zaphod Beeblebrox Posted June 29, 2015 Posted June 29, 2015 Thanks ZB. Would bypassing an electro input cap with any of the above be of any tangible benefit in a vintage amp like this? None whatsoever. The mere fact that you've dumped the electros in preference for the plastic film caps should give you a decent lift in performance. If you must experiment with a bypass cap, then use a 10nF styro.
Sub Sonic Posted June 29, 2015 Author Posted June 29, 2015 Thanks ZB. I'm not likely to have a play if the plastic films give decent performance. BTW the 4.7 caps definitely look like input coupling caps, one is in the top left red circle in the schematic below. 1
Sub Sonic Posted June 29, 2015 Author Posted June 29, 2015 100uf 16V Nichicon EPs and 4.7uF Panasonic ECWF(A) caps now ordered, thanks for all the help! Regards, SS 1
Sub Sonic Posted July 1, 2015 Author Posted July 1, 2015 The new caps are in, and pots and selector switch DeoxIT ed. I've set the bias to 20mV measuring at the test points, just waiting for it to warm up to readjust. I think 20mV is correct, can anyone confirm by the circuit diagram above? I assume +0.005V through zero to -0.015V equals 20mV? One channel was around 30mV, the other was around 90. I did wriggle the pots earlier when using the Deoxit, so may not have gotten them back exactly in the original position, hence the initial incorrect settings. Cheers! SS
surprisetech Posted July 3, 2015 Posted July 3, 2015 Nice job. Great to see you got around to doing this. I should get myself organised and do mine one wet weekend. I must take note of all the suggestions and contributions in this thread before I start.
Sub Sonic Posted July 3, 2015 Author Posted July 3, 2015 Nice job. Great to see you got around to doing this. I should get myself organised and do mine one wet weekend. I must take note of all the suggestions and contributions in this thread before I start. It's definitely an enjoyable one to do as it's so easy, 5 screws and both the top and bottom panels come off, giving full access. The last thing I need to do is to get the VU lights working, haven't had a chance to look at that one yet. Regards, SS
Sub Sonic Posted July 4, 2015 Author Posted July 4, 2015 (edited) Thanks for the tip. Just trying to work out the voltage of the lamps. I'm a bit stuck as they are not labelled, are all in series with each other and also with two resistors. As one is blown I can't even measure the current to work it out from there. Edit: If I'm not mistaken, the supply voltage across the whole setup would be around the 50-55V mark, AC. Edited July 4, 2015 by Sub Sonic
Zaphod Beeblebrox Posted July 5, 2015 Posted July 5, 2015 The lamps will likely be either 6 Volts, 9 Volts or 12 Volts. Remove them all and see if you can locate one that works. Connect it to a 6 Volt power supply (or batteries). It should light up with a yellow glow (not white). Briefly try 9 Volts. WES carry replacements in all Voltages, though I'd replace them all with Lumiledsâ„¢. That would require considerably more effort though. 1
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