geoturbo
tinkerer w/o highly evolved auditory stimulus cpu
I just got this Rel Strata III subwoofer with a non working 100W amp, year of built is around early 2000; I will be trying to share/get suggestions how to fix this amp or failing miserably
The amp board appears heated in multiple spots:
I found some very valuable information googling the internet about other similar issues:
https://www.diyaudio.com/forums/solid-state/198466-own-rel-sorm-iii-sub.html
Some components in the burnt areas appear to be those suggested to be swapped:
Change Q9 & Q10 (BF469, NPN) to MJE340
Change Q4 & Q5 (BF470, PNP) to MJE350
Change R8 (12k, 2 Watt) whilst measuring ok to 15K, 3 Watt or better, 5%
Change R6 (10k, smd, 1/8 Watt, drifted to 8400ohm!) to 22K, 1%
plus some other to be checked in values. Of these, smd R1 resistor appears to have drifted.
and will be substituting C2+C3 psu smoothing caps (6800uF 63V per cap to 10000uF 63V) and few electrolytics (C5, C14, C16 from 100uF 25V to 100uF 35V or better).
so I just ordered the parts mentioned and will try a repair in house.
I would also like to ask whether anyone has made some modifications to the output mosfets with good experience.
The amp is having a single set of BUZ900 + BUZ905 output mosfets which are rated at 125W 160V, however due to heating conditions in standard form I reckon it is not very safe to upgrade the mosfets to BUZ900D/901D + BUZ905D/906D rated at 250W or add a second pair of BUZ900 + BUZ905 in parallel..
The amp board appears heated in multiple spots:
I found some very valuable information googling the internet about other similar issues:
https://www.diyaudio.com/forums/solid-state/198466-own-rel-sorm-iii-sub.html
Some components in the burnt areas appear to be those suggested to be swapped:
Change Q9 & Q10 (BF469, NPN) to MJE340
Change Q4 & Q5 (BF470, PNP) to MJE350
Change R8 (12k, 2 Watt) whilst measuring ok to 15K, 3 Watt or better, 5%
Change R6 (10k, smd, 1/8 Watt, drifted to 8400ohm!) to 22K, 1%
plus some other to be checked in values. Of these, smd R1 resistor appears to have drifted.
and will be substituting C2+C3 psu smoothing caps (6800uF 63V per cap to 10000uF 63V) and few electrolytics (C5, C14, C16 from 100uF 25V to 100uF 35V or better).
so I just ordered the parts mentioned and will try a repair in house.
I would also like to ask whether anyone has made some modifications to the output mosfets with good experience.
The amp is having a single set of BUZ900 + BUZ905 output mosfets which are rated at 125W 160V, however due to heating conditions in standard form I reckon it is not very safe to upgrade the mosfets to BUZ900D/901D + BUZ905D/906D rated at 250W or add a second pair of BUZ900 + BUZ905 in parallel..