1cheesepasty
New Member
Afternoon all,
With the similarities between Marantz and Superscope, I'm hoping that this is an appropriate forum to post this request. Sorry for the length of the post but I feel it's helpful to know where I'm coming from. A bit of history first...
I picked up a mid-seventies Superscope R-1270 on eBay for £50. The seller said that it was in showroom cosmetic condition but all bulbs needed replacing. This was all true.
I replaced the bulbs, switched on and it sounded fine, for all of five minutes. Gradually, the sound quality got worse and worse and worse until it was unlistenable. After a week of research on AK and with the use of my trusty multimeter, I discovered that the voltages from the power supply board (P800) were all over the place and any attempt to adjust them failed.
So after careful planning, I took a deep breath, lashed up a DBT and ordered a batch of replacement caps and a transistor with the intent of recapping P800 to see if this made any difference. To cut a long story short, despite congenital issues with my hand\eye co-ordination, I managed to install the new components and was as surprised as anyone, when the receiver sprang into life first time following my repair.
Perhaps this is foolishness on my part, but the sense of achievement I got from that job has lead me to consider recapping other boards on this receiver. I feel that, although the R-1270 is quite a small unit, the one that I have can perform better than it currently does.
The next board to work on on my list is PE01 tone amp. Compared to the power supply board, it looks reasonably accessible and working on it will also give me the chance to thoroughly clean the treble and bass pots. Here's my outline plan of attack.
- Carefully pull back board until it is wholly visible, mark "Front" position on all capacitors and confirm values.
- Take lots of photos of board and confirm wire colours attached to jumpers
- Compare capacitor values to parts list and resolve any discrepancies. Installed cap takes preference.
- Consult Mouser and identify potential replacement parts. In general, any electrolytics less than or equal to 4.7uF will be Wima MKS2s while the sole one above that value (100uF, 35v) will be an Elna Simlic
- Compare size\lead spacing between installed and proposed parts to ensure that proposed will fit.
- Order parts
- Clean pots and worry about how I'm eventually going to replace the dual section filter capacitor while waiting for parts
- Install new components, carefully ensuring that the polarity of replacements matches that of the originals then sit back and enjoy the improved performance.
There's not much information on recapping Superscopes on AK so I've based a lot of my reasoning on similar Marantz devices. I would be extremely grateful if folks could point out any problems with my reasoning or make recommendations based of the schematics that I've uploaded.
Oh, almost forgot. If you think that I should accept that having a working Superscope receiver from 1976 is a result in itself and that playing about with capacitors isn't going to make that much difference, I'm happy to take that as an answer too.
Thanks very much for your help,
Clive
With the similarities between Marantz and Superscope, I'm hoping that this is an appropriate forum to post this request. Sorry for the length of the post but I feel it's helpful to know where I'm coming from. A bit of history first...
I picked up a mid-seventies Superscope R-1270 on eBay for £50. The seller said that it was in showroom cosmetic condition but all bulbs needed replacing. This was all true.
I replaced the bulbs, switched on and it sounded fine, for all of five minutes. Gradually, the sound quality got worse and worse and worse until it was unlistenable. After a week of research on AK and with the use of my trusty multimeter, I discovered that the voltages from the power supply board (P800) were all over the place and any attempt to adjust them failed.
So after careful planning, I took a deep breath, lashed up a DBT and ordered a batch of replacement caps and a transistor with the intent of recapping P800 to see if this made any difference. To cut a long story short, despite congenital issues with my hand\eye co-ordination, I managed to install the new components and was as surprised as anyone, when the receiver sprang into life first time following my repair.
Perhaps this is foolishness on my part, but the sense of achievement I got from that job has lead me to consider recapping other boards on this receiver. I feel that, although the R-1270 is quite a small unit, the one that I have can perform better than it currently does.
The next board to work on on my list is PE01 tone amp. Compared to the power supply board, it looks reasonably accessible and working on it will also give me the chance to thoroughly clean the treble and bass pots. Here's my outline plan of attack.
- Carefully pull back board until it is wholly visible, mark "Front" position on all capacitors and confirm values.
- Take lots of photos of board and confirm wire colours attached to jumpers
- Compare capacitor values to parts list and resolve any discrepancies. Installed cap takes preference.
- Consult Mouser and identify potential replacement parts. In general, any electrolytics less than or equal to 4.7uF will be Wima MKS2s while the sole one above that value (100uF, 35v) will be an Elna Simlic
- Compare size\lead spacing between installed and proposed parts to ensure that proposed will fit.
- Order parts
- Clean pots and worry about how I'm eventually going to replace the dual section filter capacitor while waiting for parts
- Install new components, carefully ensuring that the polarity of replacements matches that of the originals then sit back and enjoy the improved performance.
There's not much information on recapping Superscopes on AK so I've based a lot of my reasoning on similar Marantz devices. I would be extremely grateful if folks could point out any problems with my reasoning or make recommendations based of the schematics that I've uploaded.
Oh, almost forgot. If you think that I should accept that having a working Superscope receiver from 1976 is a result in itself and that playing about with capacitors isn't going to make that much difference, I'm happy to take that as an answer too.
Thanks very much for your help,
Clive
