Apparently the power switch got kicked/knocked by accident and now doesn’t work 🙁 Can’t get to it easily so it’s front panel off time again, 51 million screws and knobs! (The switch is secured to the chassis behind the panel with two screws) Oops 1: Oops 2: A rather hard to find lever switch (centre […]
The Technics SU-3500 is back Read More »
Customer didn’t find the output particularly pleasing and wanted a better speaker fitting, but not to go overboard… Old speaker out: New budget 6.5″ Eurotec 30W speaker arrived: Much beefier (probably too good for it!): Installed into cabinet and tested, customer happy.
Speaker upgrade for small practice amp cabinet Read More »
What quite shocking PCB build quality! This small amp came in dead, and whilst looks ok from the outside, the inside leaves a lot to be desired… Everything is… sort of… just all over the place: The soldering is some of, if not the worst I’ve ever seen… Even one transistor leg wasn’t even soldered:
Mini Mofo 15 watt valve amp head Read More »
A friend bought a faulty Kairn and asked me if I could fix… Sold as ‘doesn’t power on’. Now the first thing that was spotted is that someone’s been messing, with a regulator completely missing: and it doesn’t get any better (battery removed, clearly faffed with to try get working, even looks like they swapped
Could this be the worst Kairn battery damage yet? Read More »
Turns out to be plastic failure in the RV4 balance fader. An ALPS part no longer made so repaired it instead… A juggling act to remove as it is levered remotely from front panel: Can see the break in the lower side and the contacts are no longer pressing against the track Nothing a good
Quad 34 one channel not working Read More »
Customer states problem started a couple of weeks previously with a crackling sound, thought it was one of their speakers at first but now got a burning smell when plugged it in so turned it off right away. Found R115 burned up – part of zobel network: Removed in order to clean up – it
Ampeg PF500 crackling/burning smell Read More »
Another dead kairn and seeing the signs already (gulp): Yep we have sparklies! But not the worst I’ve seen. it just travels everywhere mainly along the negative current paths. Typically happens when battery is flat (not been plugged in for a long time) Cleaned up with water, neutralised with citric acid, and repair any traces
Another Linn Kairn battery leak repair Read More »
Right hand channel output transistors BDV 65B and BDV64B shorted and took out 0.22 ohm emitter resistors which very quickly went open circuit. NOS ST brand BDV parts acquired and fitted to the dead channel, along with new 1W wirewound resistors Always wise to check output for DC offsets etc before connecting to speaker and
Bang and Olufsen Beomaster 5500 amplifier blown channel Read More »
This was one of the more unusual repairs (if there is such a thing) – tractor mower JCB D20/50 dead in the water, nothing working, was playing up but now doesn’t do anything, main pc board module failure suspected. Was potted in silicone, so scraped off the bottom (came away quite easily as the whole
JCB/Countax D20-50 lawnmower main pcb/computer module Read More »
This lovely example of 70’s Japanese workmanship came in with no output. Turns out +57V and -57V rail rectifiers (double-diodes D501 and D502) one had gone short circuit, and taken out both 2.2 ohm R501/R502 1/8W fusible resistors. As these were now unobtainium (CO8P-1 and CO8P-1R) they were temporarily replaced with 1/8W and couple of
Technics SU-3500 powers up but no output Read More »
Customer asked to check state of valves in case they needed replacement and a quick check over everything else, plus a rattle… Very impressed by the build quality: Valves recommended to be replaced after 5000 hours use, am seeing no degradation or need to change at this stage: However a couple of minor issues were
Avalon VT737SP valve compressor checkup/service Read More »
No power, fuse blown, found mosfet switching transistor shorted in PSU section, perhaps due to a power spike, and usually other stuff blows, but could be lucky and only be that… Mosfet (STB36NM60ND) was a pig to get out as not much space and the heatsink soldered to the board, but a combination of hot
Peavey Mini Max class D bass amp dead Read More »
Dishwasher was not heating up, element had continuity and relay was clicking but no power getting to element. Relay contacts worn out: Replacement Omron relay ordered and fitted Then after replacing the board back in the machine to test, discovered the ULN2003A IC had subsequently failed, so this was also replaced and everything back in
Baumatic dishwasher not heating Read More »
Intermittent crackling noise – which proved to be quite elusive… There was some aluminium shielding tape which exhibited a little noise when amp module was moved slightly, so made a better connection to that, also found a dry solder joint and replaced NE5532 op-amp. And whilst in there, gave all the sliders and pots a
Dynacord BS412 Bass Amp Read More »
Missing knob, reverb not functioning, loud pop on shutdown, volume pots very sensitive (almost full volume by quarter point). Genuine Fender replacement pots with audio taper ordered from US to replace existing linear (not sure why they were linear): and fitted: Added an arc suppression cap across switch load contacts to reduce power off pop
Fender Princeton 112 Plus repairs Read More »
