was bored, could not read blog yesterday. So out of sheer boredom I had a look at my Nakamichi OMS-2. Using a scalpel I cut out those 2 caps in the audio path atop of the glue that looked, umm, suspicious.
After a wee bit of desoldering they came out just fine. Only problem was the grumpy husband who had to hold the pcb - I did not want to remove it from the chassis as I would have had to disconnect the laser pickup. Which is extremely susceptible to ESD, any Nak service manual warns that if you disconnect it without shorting it out first, you will blow the laser.
The original caps are no longer available. Looking at the caps that were originally used, these were Nichicons for the PSU and ELNA for the audio circuits.
This is what I got.
2 x (ELNAC-115) - 220uF 16V Elna Cerafine Electrolytic Capacitor - £2.04 (£1.02 each)
SKU: ELNAC-115, Location: AJ09, Tariff Code: 8532220000
2 x (ELNAS-165) - 1000uF 6.3V Elna Silmic II Electrolytic Capacitor - £2.76 (£1.38 each)
SKU: ELNAS-165, Location: AJ10, Tariff Code: 8532220000
4 x (ELNAS-150) - 470uF 16V Elna Silmic II Electrolytic Capacitor - £5.72 (£1.43 each)
SKU: ELNAS-150, Location: AJ10, Tariff Code: 8532220000
2 x NFG-870 - 2200uF 16V FG Nichicon type, UFG1C222MHM - £3.20 (£1.60 each)
SKU: NFG-870, Location: AJ11, Tariff Code: 8532250000
2 x NFG-890 - 2200uF 35V FG Nichicon type, UFG1V222MHM - £4.10 (£2.05 each)
SKU: NFG-890, Location: AJ11, Tariff Code: 8532250000
Inspecting the first pair of ELNAs after desoldering it turned out that the Caps themselves did not show any physical sign of damage. Measuring them gave me 451 / 452u which puts them within 5% of the advertized rating. Also they seem to be very well matched.
However some of that glue was sticking to one of the + terminals (eees zeees ze right word ? sorry my terminology sucks) and was seriously discolored and was crystallizing (?) which just does not seem right.
Anyway. After fixing this up when using a headphone I could not make out any more distortions.
So next step is to hook this up to the big preamp and give it a go.