Repairs

Rather forlorn-looking woofer from a Technics organ with disintegrated foam surround. Cut away the old material before prepping for surround replacement: New surround interior-glued to the cone and wait for curing Support the edges of the cone and verify central placement (important to ensure the coil is free from dragging in the narrow gap –

Customer stated that they inadvertently connected the speaker output to a mixer rather than the line output, and claimed it stopped working, no longer any output. Clean some of the compound away to see the damage (obliteration and vaporisation of the ICs and surrounding tracks).. This one is going to be a challenge: Ordered replacement

Customer brought in a couple of Lux91 300B-based amps, one suddenly stopped working. First off noticed customer had inadvertently managed to remove and reinsert the 300B 4-pin valve rotated 90 degrees (as a ‘diy’ check swapping valves between units) prior to bringing to me which of course failed to fix anything. Thankfully nothing damaged being

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

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:

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

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

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

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