ahpook Posted June 22, 2014 Share Posted June 22, 2014 For some time now my trusty old SVP-Pro has been cutting out, I've had it serviced and tried replacing what seemed to be a dodgy valve, but to no avail. Finally today it completely died. I buckled down witha multimeter this afternoon and finally traced the fault to the transformer, which isn't putting out any juice at all (Plate volatge, heater current, etc - all zero). (Sob) From what I can find on the web, replacement transformers are hard to find short of getting another SVP-Pro. Anyone had any experience of having a transformer rewound ? Any idea on how much it would cost ? Quote Link to comment Share on other sites More sharing options...
paul_5 Posted June 22, 2014 Share Posted June 22, 2014 Panic music in Cambridge ( I think) are the only authorised dealer for Ampeg spares in the UK, but the trannies you get these days just don't seem to be that good. If I remember correctly there's a company in Ipswitch who rewind transformers. Quote Link to comment Share on other sites More sharing options...
ahpook Posted June 22, 2014 Author Share Posted June 22, 2014 Thanks- I'll try and track them down. Quote Link to comment Share on other sites More sharing options...
paul_5 Posted June 22, 2014 Share Posted June 22, 2014 The transformer rewir company were recommended by Derek at Watford Valves, so it might be worth giving them a call. If you speak to Derek it won't be a short phone call, but what he doesn't know about about 'pegs ain't worth knowing. Quote Link to comment Share on other sites More sharing options...
ahpook Posted June 22, 2014 Author Share Posted June 22, 2014 [quote name='paul_5' timestamp='1403469934' post='2483041'] The transformer rewir company were recommended by Derek at Watford Valves, so it might be worth giving them a call. If you speak to Derek it won't be a short phone call, but what he doesn't know about about 'pegs ain't worth knowing. [/quote] Brilliant - I've been looking around for some people to call, I'll give them a bell tomorrow. Quote Link to comment Share on other sites More sharing options...
ahpook Posted June 23, 2014 Author Share Posted June 23, 2014 Just had my 1st quote back - almost £300 including VAT. feck. Quote Link to comment Share on other sites More sharing options...
paul_5 Posted June 23, 2014 Share Posted June 23, 2014 (edited) Edited June 23, 2014 by paul_5 Quote Link to comment Share on other sites More sharing options...
ahpook Posted June 24, 2014 Author Share Posted June 24, 2014 (edited) Last night I decided to give the power board one more thorough check - still nothing.... So, what the hell I thought....it's going to have to come out anyway, and carefull desoldered and removed the transformer. And there it was... One of the tags on the transformer's primaries had snapped inside the board hole, so although the tag looked nice and secure there was no solid connection - in fact I've continuity tested all these tags before to make sure there was a good solder connection to the board. It must have just been resting against the unsnapped part that was soldered to the PCB. Hence the intermittent cut-outs in the past. So I installed a flying wire on the transformer tag and ran it to the next solid connection on the board, resoldered the good tags in and at ~3am this morning i finally got it working. My pessimistic outlook means I'll refrain from calling it 'fixed' for a while, but all the evidence points to this being the problem. Oh, and I only electrocuted myself once ! Edited June 24, 2014 by ahpook Quote Link to comment Share on other sites More sharing options...
JTUK Posted June 24, 2014 Share Posted June 24, 2014 Sounds a good outcome. Good work. Quote Link to comment Share on other sites More sharing options...
paul_5 Posted June 24, 2014 Share Posted June 24, 2014 Brilliant news! Also, do you find that your post-electric shock soldering is a bit tricky until the shakes have stopped? Quote Link to comment Share on other sites More sharing options...
ahpook Posted June 24, 2014 Author Share Posted June 24, 2014 [quote name='JTUK' timestamp='1403606541' post='2484321'] Sounds a good outcome. Good work. [/quote] Thanks ! [quote name='paul_5' timestamp='1403609326' post='2484359'] Brilliant news! Also, do you find that your post-electric shock soldering is a bit tricky until the shakes have stopped? [/quote] Very much so ! Just be careful of those smoothing caps folks...watch where your fingers are going when you touch the underside of the board ! Quote Link to comment Share on other sites More sharing options...
Dad3353 Posted June 24, 2014 Share Posted June 24, 2014 [URL=http://www.smileyvault.com/][IMG]http://www.smileyvault.com/albums/userpics/13049/applause.gif[/IMG][/URL] Brilliant..! Would get full marks except for the electrocution. That's just a warning shot; some folks have been killed or seriously injured from working in valve amps without adequate precautions. You were lucky, there. Enjoy your newly repaired amp..! Quote Link to comment Share on other sites More sharing options...
ahpook Posted June 24, 2014 Author Share Posted June 24, 2014 [quote name='Dad3353' timestamp='1403613292' post='2484452'] [url="http://www.smileyvault.com/"][/url] Brilliant..! Would get full marks except for the electrocution. That's just a warning shot; some folks have been killed or seriously injured from working in valve amps without adequate precautions. You were lucky, there. Enjoy your newly repaired amp..! [/quote] Thank you, and an entirely fair point about the shock - I may joke, but I'm disappointed with myself about getting it - I know I know better ! Quote Link to comment Share on other sites More sharing options...
BassTractor Posted June 24, 2014 Share Posted June 24, 2014 [quote name='ahpook' timestamp='1403604414' post='2484289'] My realistic outlook means I'll call it 'fixed', as all the evidence points to this being the problem. [/quote] Fixed! Congrats, and well done! (except maybe the Virgil Ovid Hawkins part) Quote Link to comment Share on other sites More sharing options...
ahpook Posted June 24, 2014 Author Share Posted June 24, 2014 [quote name='BassTractor' timestamp='1403622651' post='2484641'] Fixed! Congrats, and well done! (except maybe the Virgil Ovid Hawkins part) [/quote] Had to check that, but Quote Link to comment Share on other sites More sharing options...
goingdownslow Posted June 24, 2014 Share Posted June 24, 2014 It's not a real shock unless your skeleton was exposed. Quote Link to comment Share on other sites More sharing options...
icastle Posted June 24, 2014 Share Posted June 24, 2014 [quote name='ahpook' timestamp='1403610409' post='2484385'] Just be careful of those smoothing caps folks...watch where your fingers are going when you touch the underside of the board ! [/quote] +1 It's unpleasant. I now habitually use a couple of big wirewound resistors wrapped in shrinksleeve with flyleads coming out to discharge smoothing caps. Quote Link to comment Share on other sites More sharing options...
ahpook Posted June 24, 2014 Author Share Posted June 24, 2014 [quote name='icastle' timestamp='1403627552' post='2484702'] +1 It's unpleasant. I now habitually use a couple of big wirewound resistors wrapped in shrinksleeve with flyleads coming out to discharge smoothing caps. [/quote] Just what I was thinking of building ! What value resistors did you use ? Quote Link to comment Share on other sites More sharing options...
paul_5 Posted June 24, 2014 Share Posted June 24, 2014 [size=6]Big 'u[/size][size="5"]ns! [/size] Quote Link to comment Share on other sites More sharing options...
BassTractor Posted June 24, 2014 Share Posted June 24, 2014 [quote name='ahpook' timestamp='1403625532' post='2484688'] Had to check that [/quote] Me too! Quote Link to comment Share on other sites More sharing options...
Subthumper Posted June 25, 2014 Share Posted June 25, 2014 10K 2 watt should do for discharging smoothing caps. Worth looking over the whole board on ampeg, they went through a period of seeing what was the least amount of solder they could use. Especially check the joints that are under stress mechanically such as the the pots, jacks and switches on the front panel. Zap anything that looks remotely poor. Well done on the fix. £300 for a pre amp transformer is ludicrous. Even an SVT transformer for Tube Amp Doctor is only about £220. Someone's taking the p#ss. Quote Link to comment Share on other sites More sharing options...
ahpook Posted June 25, 2014 Author Share Posted June 25, 2014 (edited) [quote name='Subthumper' timestamp='1403735306' post='2485881'] 10K 2 watt should do for discharging smoothing caps. Worth looking over the whole board on ampeg, they went through a period of seeing what was the least amount of solder they could use. Especially check the joints that are under stress mechanically such as the the pots, jacks and switches on the front panel. Zap anything that looks remotely poor. Well done on the fix. £300 for a pre amp transformer is ludicrous. Even an SVT transformer for Tube Amp Doctor is only about £220. Someone's taking the p#ss. [/quote] I've been over the power board and reflowed all the solder joints once already It was a tidy job to start with, but I wanted to remove it from the equation. I'll give the preamp board it a going over next time I've got it open - I've checked it with a mangnifier, but maybe some reflows might be order there too. Good advice, thanks. I'm still waiting for another quote for rewinding the transformer, I hope it's cheaper too - I just wish there was space in the case to move it off the power board. It [i]should[/i] have been chassis-mounted in the first place, not held on to the board by solder and ziplock tags ! Edited June 25, 2014 by ahpook Quote Link to comment Share on other sites More sharing options...
paul_5 Posted June 26, 2014 Share Posted June 26, 2014 I'd also question how exactly it was 'serviced' and nobody noticed the fault. Quote Link to comment Share on other sites More sharing options...
ahpook Posted July 4, 2014 Author Share Posted July 4, 2014 (edited) It's cutting out again. Edited July 4, 2014 by ahpook Quote Link to comment Share on other sites More sharing options...
ahpook Posted July 4, 2014 Author Share Posted July 4, 2014 [quote name='paul_5' timestamp='1403808801' post='2486746'] I'd also question how exactly it was 'serviced' and nobody noticed the fault. [/quote] Indeed. I think my next port of call will be the Bass Gallery for a 'real' service. Quote Link to comment Share on other sites More sharing options...
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