basstone

I might be interested in your ICEpower modules, especially if they are 125ASX2.

They look great from the pictures on the web site as well. Can't wait to see and hear them on Sunday. I too am a BC112 Mk3 owner/ builder using one of the first batch of cabinet kits so have high expectations! I wonder if there's any possibility of upgrading the DIY design without a total rebuild?

What amp is it? I repair amps, my business is Hurst Batch Services based in Wells and I'll be at the bash. Sadly, some modern amps are not repairable by independent repairers due to method of construction and lack of manufacturer support.

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You live and learn! I don't get involved with much SMT but a short google search came up with the EIA-96 codes which would indicate that 35C is 226 X 100 or 22.6Kohms as 35 is code for 226 and C is a x100 multiplier. All potentially quite confusing and ambiguous if the markings become worn! Fingers crossed for the repair

R140 looks like 350 ohms from this photo and R141 as already noted on the other side of the board. Worth trying a temporary "breadboard" fix with a standard resistor to see if it all springs back to life?

I trade as Hurstbatch Services, based in Wookey Hole, repairing all types of music gear. I'm happy to discuss any specific requirements.

It's possibly just a poor connection. Are all of the controls and switches working well and scratch free? Same for the connectors. It's also worth trying the jumper cable test between the effect send and return in case there is a poor connection in one of the jack sockets. Also a sharpish bang just with your hand when first switched on might help to confirm if there is a poor connection within the circuit? Next stage is to test to see if the DI output and effect send are also affected to help localise the fault. Pretty much whatever it is will require the amp to be opened up, inspected and then fault diagnosis and repair done. Any experienced engineer should be able to help you get it fixed. Good luck

Looks like a conventional class A/B power amp module to me along with auxiliary low voltage power supplies for the preamp, probably + - 15v DC. It is suspicious that the DI output is not working as that comes from the preamp, so the fault may not be the power amp at all or there may be multiple faults. It will also be worth checking that the thermal cutout (mounted on the heatsink) has good continuity. If the transformer is good (likely as it lights up) one option would be to replace the power amp if it is indeed the fault, with a readily available MOSFET power amp module. The power output might not be quite the same but I doubt that you'd notice the difference. Class D modules are available, notably Icepower, which are powered directly from the mains and handily have auxiliary DC power outputs for preamps, however these are not cheap!. You would need to figure out the preamp power requirements and either reuse the existing regulators or provide new and wire it correctly. None of this is technically difficult for an experienced engineer but it might not be cost effective, depending what value you place on the amp. Your best option of all will be to find a competent repairer who will accurately diagnose the problem and propose the best cost effective fix. There is an index of repairers on the forum, although probably a bit out of date now. Where are you based? I'm a repairer based in Somerset if you're anywhere near to me I'd be happy to have a proper look

Looks like R140 and R141 are both missing. Both small SMD items so not much power dissipation I think? Those solder pads also look damaged. It looks like the short was to the pillar on the left judging by the melted bit and black soot?

I'm a repairer based near to Wookey Hole, not too far away. I can't promise anything but happy to have a look if you can get the amp to me.

Agree to all of the above. In my experience Ashdown are great to deal with and always prepared to go the extra mile to help out.

Hopefully if the thread is kept active someone will spot it and offer to take a photo. If you can't get a photo, another, not so easy option, is to trace that part of the circuit out and figure out what the component does. Depending on accessibility and the board construction this could be tricky and time consuming! The only 2 variables are its resistance and power rating. There is hopefully some clue of power rating at least based on the size / lead spacing of the old component. Depending on its function, the exact value may not be that critical.

Can you be sure that this is the only faulty component? Has everything else been tested at component level? Unless the circuit and the failure mode is known there may be other issues lurking in there as well. Of course you may be correct and just a resistor is needed and it's certainly worth a trying a replacement if you can find out what the value is. The only other suggestion that I can offer is that someone else who has the same amp could take a photo of the circuit board to identify the value of the resistor in question. Anyway good luck with it.

Hi there, Sorry to hear that your Markbass combo is faulty. It's probably a back to Markbass or their approved repairer job as Markbass don't encourage or support independent repairers in my experience. It might be worth contacting them to get a quote as a starting point. Having said that, if it's a simple easy to find and repair fault any competent repairer may be able to help and if you know of one it might also be a lower cost option. Where are you based?