warwickhunt Posted April 9, 2008 Share Posted April 9, 2008 I need to make a decision as to whether to take a GK 800rb in as part-ex but it has some issues. Namely; it pops on power up and down and it has a degree of distortion, especially as the note dies away. I'm a bit critical of noise but the guy at my local rehearsal rooms that I've just called into (another thread) reckoned he's gigged worse amps! My question is... has anyone any experience of similar issues? Obviously I can take it to a tech but it's going to cost me money to even have it looked at and if it's an expensive fix I'll not even bother. However, if as it has been suggested by the guy at the rehearsal rooms it is capacitors failing and it's an easy inexpensive fix (would it be?) I'll strike a deal. A GK800rb anyone? Quote Link to comment Share on other sites More sharing options...
clauster Posted April 9, 2008 Share Posted April 9, 2008 Nice amp, I like those 800RBs! Could be caps. Cost of replacing them depends exactly on what they are. Only way to be certain is open the thing up, make sure the caps are safely discharged and get a multimeter on them. If you don't mind me asking, what trade-in value is riding on the amp? Quote Link to comment Share on other sites More sharing options...
warwickhunt Posted April 9, 2008 Author Share Posted April 9, 2008 [quote name='clauster' post='173129' date='Apr 9 2008, 02:18 PM']Nice amp, I like those 800RBs! Could be caps. Cost of replacing them depends exactly on what they are. Only way to be certain is open the thing up, make sure the caps are safely discharged and get a multimeter on them. If you don't mind me asking, what trade-in value is riding on the amp?[/quote] As it stands, if the amp were working with no issues he wants £330. I have no use for the amp so I'd need to ensure that whatever I knock off for it I need to get back by selling it on here or in the local paper. I'm not about to ruin a reputation by selling something that is duff so I'm not diving in feet first. I need to do a search really as I'm sure someone on here was asking about 800rbs in an unrelated thread a while back. We'll see. Quote Link to comment Share on other sites More sharing options...
clauster Posted April 9, 2008 Share Posted April 9, 2008 Wise move. Quote Link to comment Share on other sites More sharing options...
warwickhunt Posted April 9, 2008 Author Share Posted April 9, 2008 Just come off the phone from speaking to the owner. He's lived with these issues for a while but has conceded it may need a service so we're looking at £250 - £275 (the latter figure is his but the former is my interpretation ) I'd still like to know if capacitors failing gives these symptoms. Hopefully I've got a Sparkie coming around any way so I may get him to test them. I'm a bit green when it comes to the guts of amps, so what do capacitors look like (don't worry my fingers won't go internal)? I'd assume that a common or garden Sparkie will know what amplifier capacitors look like! Quote Link to comment Share on other sites More sharing options...
clauster Posted April 9, 2008 Share Posted April 9, 2008 If it's the big output stage caps they'll probably look a bit like a very small drinks can on pins. Every competent amateur can tell the main components apart. so with a qualified electrician you've got no worries. Quote Link to comment Share on other sites More sharing options...
tauzero Posted April 10, 2008 Share Posted April 10, 2008 [quote name='warwickhunt' post='173191' date='Apr 9 2008, 03:10 PM']I'd still like to know if capacitors failing gives these symptoms.[/quote] I have a Laney DP150 combo that started distorting somewhat - rather scrapey sort of noise. Over headphones, it sounded fine. I was worried about a failing speaker driver but somehow (can't remember how) worked out it was the amp. Replaced the power supply capacitors (summat like 22000 uF) and that solved the problem. Quote Link to comment Share on other sites More sharing options...
warwickhunt Posted April 10, 2008 Author Share Posted April 10, 2008 [quote name='tauzero' post='173903' date='Apr 10 2008, 01:42 PM']I have a Laney DP150 combo that started distorting somewhat - rather scrapey sort of noise. Over headphones, it sounded fine. I was worried about a failing speaker driver but somehow (can't remember how) worked out it was the amp. Replaced the power supply capacitors (summat like 22000 uF) and that solved the problem.[/quote] What sort of cost for that job (I realise it may not be that or that the cost may well vary due to manufacturer/power etc.)? Quote Link to comment Share on other sites More sharing options...
tauzero Posted April 11, 2008 Share Posted April 11, 2008 [quote name='warwickhunt' post='173973' date='Apr 10 2008, 03:29 PM']What sort of cost for that job (I realise it may not be that or that the cost may well vary due to manufacturer/power etc.)?[/quote] Cost me somewhere round a tenner for the two capacitors IIRC. I did the work myself, it's not hard (except for remembering where you've put the bolts that hold the amp into the top of the cab, must get some new ones...). Quote Link to comment Share on other sites More sharing options...
warwickhunt Posted April 11, 2008 Author Share Posted April 11, 2008 [quote name='tauzero' post='174668' date='Apr 11 2008, 04:34 PM']Cost me somewhere round a tenner for the two capacitors IIRC. I did the work myself, it's not hard (except for remembering where you've put the bolts that hold the amp into the top of the cab, must get some new ones...).[/quote] £10... if it's anywhere near that (I've budgeted £40) for a DIY job then I'll be happy. Saying that I'd love to hear from 800RB owners as I've phoned an amp tech up and he reckons that it's just what 800RBs do! Quote Link to comment Share on other sites More sharing options...
clauster Posted April 12, 2008 Share Posted April 12, 2008 I've not owned an 800RB (yet ) but I was reading the other day that they can make some odd noises - the fix is to put a patch-lead in the effects loop (assuming nthing else is there already). Sounds mad, but it might be worth a try? Quote Link to comment Share on other sites More sharing options...
warwickhunt Posted April 12, 2008 Author Share Posted April 12, 2008 [quote name='clauster' post='175128' date='Apr 12 2008, 12:54 PM']I've not owned an 800RB (yet ) but I was reading the other day that they can make some odd noises - the fix is to put a patch-lead in the effects loop (assuming nthing else is there already). Sounds mad, but it might be worth a try?[/quote] I might try that! Cheers. If this one interests you I've got the guy down to a trade in of £240, so that's all I'd want back (+£10 postage). It also has a flightcase but it's not much to write home about. Quote Link to comment Share on other sites More sharing options...
clauster Posted April 14, 2008 Share Posted April 14, 2008 It interests me muchly, but unfortunately skinter than a very skint thing at the mo. Quote Link to comment Share on other sites More sharing options...
warwickhunt Posted April 17, 2008 Author Share Posted April 17, 2008 I've fired the amp up today (road works no longer outside and no gennie powering traffic lights) and it seems to be fine. I'll give it a thorough test tonight and then stick it up for sale with the case. Thanks one and all Quote Link to comment Share on other sites More sharing options...
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