Out with the old.
There's a few of those pesky VD1212's in there that got replaced with series 1N4148* along with any fusistors and all the trimpots were replaced with Bourns multiturn units.
FG series on the VR/MC amp board. All boards cleaned and defluxed after the rework.
Mostly KW on the power board, yea overkill, but cheap enough for me when ordered in bulk from Mouser.
I may just start using KT (105* audio caps) for power if I can find all the right values.
Raised the power trans heatsinks off board with a couple shoulder washers. There's a .47uf polar lytic still hiding in there still to be dealt with. I didn't clean the dust off well enough when I was gathering info to see it was not simply the same as the other one nearby.
The A-1 already has polypropylene film bypass caps installed with the filter caps. Panasonic T-HA series and a couple ES Muse bipolars here. Preemptively replaced the speaker relay as I usually have a few of these popular relays in the bin.
Vampire BPHEX goodness.
Stock screw insert block removed intact and replaced with a solid delrin backing plate to mount the new posts.
A near perfect fit. No trimming required.
Heatsinks get washed and new mica/thermal paste used just like Yamaha intended.
Those OE Sankens are heavy duty puppies.
No lytics whatsoever on the amp board.
I felt a bit let down by all the A-1 hype when I first got it. I thought it was a little thin at first listen. It sounds fuller now than it did prior to the recap. Bass has more punch to it and the soundstage is slightly improved. I didn't get a chance to listen to any vinyl on it before, and don't own an MC cart, but surely the move from regular ol caps to FG series Nichicons should improve things. If nothing else, I know it's good for another 30 years.
Now if I could just get the idle current to adjust... :scratch2:
The SM wants a 8* 70W load connected to the speaker outputs during adjustment and I don't have anything built yet. Seems bench speakers aren't cutting it.
* I wasn't paying attention to the board markings and mis-oriented one of the 4148 series pairs used to replace the VD1212 regulator diodes. That little mistake caused a fair bit more work, one 2SA914 transistor and a grip of resistors.
Edit 12-18-2011 -- I seem to get a lot of PM's asking for parts lists.
As can be found readily on AK, VD1212 diodes are replaced with two 1N4148 or similar switching diodes wired in series.
Here's my Bourns Trimmer parts list, those used in the A-1 bolded:
Mfr PN MFR VALUE Watts Temp Range Dim Product
3299P-1-101LF Bourns 100 Horiz - side Trimmer, multiturn (pair on Amp Drive card)
3299P-1-201LF Bourns 200 Horiz - side Trimmer, multiturn
3299P-1-102LF Bourns 1k Horiz - side Trimmer, multiturn
3299P-1-202LF Bourns 2k Horiz - side Trimmer, multiturn (single 2.2K on PS card)
3299P-1-502LF Bourns 5k Horiz - side Trimmer, multiturn
3299Y-1-101LF Bourns 100 Vertical Trimmer, multiturn (pair on Pre-amp board)
3299Y-1-201LF Bourns 200 Vertical Trimmer, multiturn (pair 220 on Tone board) (pair 220 Ohm [VR301/VR302] on the VR/SW board for MC head amp distortion)*
3299Y-1-102LF Bourns 1K Vertical Trimmer, multiturn (pair on Electrolytic board)
3299Y-1-202LF Bourns 2k Vertical Trimmer, multiturn
3299Y-1-502LF Bourns 5k Vertical Trimmer, multiturn
This series of trimmer cases fit well on nearly every Yamaha I've redone. However, they do require the leads be bent to fit the PCB. I'll try to get a pic posted of the method I use.
Fusistors were replaced with metal film flameproof. Depending on voltage and current flow, 1/4W or 1/2W are preferred. However, all I had on hand were 1W so I'm risking some damage if there's a catastrophic failure. On the other hand, it's well known that transistors will always sacrifice themselves to protect their fusistors. My main goal was to provide stability and prevent drift that's common with the little buggers.
I used a common Omron MY02-DC12 for the speaker relay (5A)
Avionic has found a higher rated Panasonic(10A?) lately but I can't find his post.
*VR301 and VR302 (220 Ohm) are adjusted through a hole in this upside down board. If you replace them with 200 Ohm vertical pots, you will have to mount them on the back side (trace side) of the board and perform an adjustment that requires a distortion meter.
There's a few of those pesky VD1212's in there that got replaced with series 1N4148* along with any fusistors and all the trimpots were replaced with Bourns multiturn units.
FG series on the VR/MC amp board. All boards cleaned and defluxed after the rework.
Mostly KW on the power board, yea overkill, but cheap enough for me when ordered in bulk from Mouser.
I may just start using KT (105* audio caps) for power if I can find all the right values.
Raised the power trans heatsinks off board with a couple shoulder washers. There's a .47uf polar lytic still hiding in there still to be dealt with. I didn't clean the dust off well enough when I was gathering info to see it was not simply the same as the other one nearby.
The A-1 already has polypropylene film bypass caps installed with the filter caps. Panasonic T-HA series and a couple ES Muse bipolars here. Preemptively replaced the speaker relay as I usually have a few of these popular relays in the bin.
Vampire BPHEX goodness.
Stock screw insert block removed intact and replaced with a solid delrin backing plate to mount the new posts.
A near perfect fit. No trimming required.
Heatsinks get washed and new mica/thermal paste used just like Yamaha intended.
Those OE Sankens are heavy duty puppies.
No lytics whatsoever on the amp board.
I felt a bit let down by all the A-1 hype when I first got it. I thought it was a little thin at first listen. It sounds fuller now than it did prior to the recap. Bass has more punch to it and the soundstage is slightly improved. I didn't get a chance to listen to any vinyl on it before, and don't own an MC cart, but surely the move from regular ol caps to FG series Nichicons should improve things. If nothing else, I know it's good for another 30 years.
Now if I could just get the idle current to adjust... :scratch2:
The SM wants a 8* 70W load connected to the speaker outputs during adjustment and I don't have anything built yet. Seems bench speakers aren't cutting it.
* I wasn't paying attention to the board markings and mis-oriented one of the 4148 series pairs used to replace the VD1212 regulator diodes. That little mistake caused a fair bit more work, one 2SA914 transistor and a grip of resistors.
Edit 12-18-2011 -- I seem to get a lot of PM's asking for parts lists.
As can be found readily on AK, VD1212 diodes are replaced with two 1N4148 or similar switching diodes wired in series.
Here's my Bourns Trimmer parts list, those used in the A-1 bolded:
Mfr PN MFR VALUE Watts Temp Range Dim Product
3299P-1-101LF Bourns 100 Horiz - side Trimmer, multiturn (pair on Amp Drive card)
3299P-1-201LF Bourns 200 Horiz - side Trimmer, multiturn
3299P-1-102LF Bourns 1k Horiz - side Trimmer, multiturn
3299P-1-202LF Bourns 2k Horiz - side Trimmer, multiturn (single 2.2K on PS card)
3299P-1-502LF Bourns 5k Horiz - side Trimmer, multiturn
3299Y-1-101LF Bourns 100 Vertical Trimmer, multiturn (pair on Pre-amp board)
3299Y-1-201LF Bourns 200 Vertical Trimmer, multiturn (pair 220 on Tone board) (pair 220 Ohm [VR301/VR302] on the VR/SW board for MC head amp distortion)*
3299Y-1-102LF Bourns 1K Vertical Trimmer, multiturn (pair on Electrolytic board)
3299Y-1-202LF Bourns 2k Vertical Trimmer, multiturn
3299Y-1-502LF Bourns 5k Vertical Trimmer, multiturn
This series of trimmer cases fit well on nearly every Yamaha I've redone. However, they do require the leads be bent to fit the PCB. I'll try to get a pic posted of the method I use.
Fusistors were replaced with metal film flameproof. Depending on voltage and current flow, 1/4W or 1/2W are preferred. However, all I had on hand were 1W so I'm risking some damage if there's a catastrophic failure. On the other hand, it's well known that transistors will always sacrifice themselves to protect their fusistors. My main goal was to provide stability and prevent drift that's common with the little buggers.
I used a common Omron MY02-DC12 for the speaker relay (5A)
Avionic has found a higher rated Panasonic(10A?) lately but I can't find his post.
*VR301 and VR302 (220 Ohm) are adjusted through a hole in this upside down board. If you replace them with 200 Ohm vertical pots, you will have to mount them on the back side (trace side) of the board and perform an adjustment that requires a distortion meter.
Last edited: