PSA: That time a blown cap in a 90s VCR taught me to always check the power supply first

Was working on a JVC HR-S9600U last weekend for a collector in Austin. Spent 2 hours chasing a noisy playback issue, swapping out belts, cleaning heads, the whole deal. Finally gave up and looked at the power supply board - sure enough, one of the filter caps was bulging. Replaced it for maybe 50 cents and the thing ran perfect. Now I always start there on anything from that era. Anyone else got a "doh" moment like that where you overcomplicated a simple fix?

3 comments

3 Comments

mark_thomas27d ago

Ever wonder if those bulging caps are actually a symptom and not the root cause? I had a Pioneer receiver from the early 90s where I swapped out three swollen caps only to have them blow again six months later. Turned out the voltage regulator upstream was slowly drifting out of spec and cooking them over time. Now I always check the voltage rails with a multimeter before and after replacing caps, especially on anything that ran hot for years. Saves me from doing the same repair twice.

clark.robin27d ago

That "voltage regulator slowly drifting" thing you mentioned - that's the real kicker. I got burned the same way on a Panasonic VCR. Replaced the caps, felt good about it. Three months later the customer called back, same problem. Felt like an idiot. Now I always probe the DC voltage before and after the regulator. If it's more than 5% off on a 12V rail, the regulator is toast too. Also a good idea to check ripple with a scope if you have one. A cap can look fine but the AC ripple can be way higher than it should be if the regulator is dying. Saves you the embarrassment of a repeat repair.

kim_west27d ago

Betting half those regulators are fine and the real issue is cheap caps. @mark_thomas you buying that?