Hi folks!
Hoping somebody out there can help - I have just got hold of a lovely Technics SP.10 Mk.II turntable and PSU.
It works fine and all runs to speed.
However when checking out the capacitors underneath the turntable there are a few with 'green legs' so they all obviously need to be replaced immediately. I have a complete set of replacement electrolytics on order for both the turntable and the PSU.
Whilst the seperate PSU is very easy for an electronics layman to set up with just a multimeter, the turntable is a different prospect.
According to the service manual one needs a dual trace scope. Unfortunately I haven't got much money to spare at the moment, but I do need something that'll allow me to adjust the SP-10 Mk.II to the following:
My question is, would the following VERY cheap PC Oscilloscope by adequate for just setting these two adjustment points:
NEW 2 Channel PC Computer Digital mini USB Oscilloscope | eBay UK
Many thanks!
- John
P.S. Full service manual available here: http://downloads.nakedresource.com/...p?technics/technics_sp10mkii_euro_service.pdf
Hoping somebody out there can help - I have just got hold of a lovely Technics SP.10 Mk.II turntable and PSU.
It works fine and all runs to speed.
However when checking out the capacitors underneath the turntable there are a few with 'green legs' so they all obviously need to be replaced immediately. I have a complete set of replacement electrolytics on order for both the turntable and the PSU.
Whilst the seperate PSU is very easy for an electronics layman to set up with just a multimeter, the turntable is a different prospect.
According to the service manual one needs a dual trace scope. Unfortunately I haven't got much money to spare at the moment, but I do need something that'll allow me to adjust the SP-10 Mk.II to the following:
An externally hosted image should be here but it was not working when we last tested it.
My question is, would the following VERY cheap PC Oscilloscope by adequate for just setting these two adjustment points:
NEW 2 Channel PC Computer Digital mini USB Oscilloscope | eBay UK
Many thanks!
- John
P.S. Full service manual available here: http://downloads.nakedresource.com/...p?technics/technics_sp10mkii_euro_service.pdf
The scope you posted only claims a useable frequency response to 3kHz...in order to set the above timing relationship to an accuracy of +/- 0.1ms I would want to use a scope with a bandwith in the low MHz range. In my experience if you replace the caps with parts of matching specification there is a good chance it will work without adjustment. These pots have probably not been disturbed since the TT was new.
Thanks for your reply Kevin.
DId you mean that - in general - caps can usually be replaced like-for-like without any adjustments being made, or have you had experience doing this with the SP-10?
Just read the service manual and it states:
"If you repair the Control circuit board or the Drive Circuit board, you have to adjust VR101 and VR102".
Thankfully the bad caps are not on any of those two boards, so I think I'll be OK just replacing those for the time being.
DId you mean that - in general - caps can usually be replaced like-for-like without any adjustments being made, or have you had experience doing this with the SP-10?
Just read the service manual and it states:
"If you repair the Control circuit board or the Drive Circuit board, you have to adjust VR101 and VR102".
Thankfully the bad caps are not on any of those two boards, so I think I'll be OK just replacing those for the time being.
Another project John 
So it would matter if the gain of the Sony was lowered
I agree with Kevin that it will work without any adjustment... I haven't looked at the circuit but what you posted is typical of older Japanese stuff. Hall effect DD motors in many early VCR's had similar adjustment procedures.
If the pots were a mile off then the motor would tend to "kick" as it fights the servo. Just leave them be I would say or use the "proper engineers" method of setting to the midpoint between the two points where lock is lost
So it would matter if the gain of the Sony was lowered I agree with Kevin that it will work without any adjustment... I haven't looked at the circuit but what you posted is typical of older Japanese stuff. Hall effect DD motors in many early VCR's had similar adjustment procedures.
If the pots were a mile off then the motor would tend to "kick" as it fights the servo. Just leave them be I would say or use the "proper engineers" method of setting to the midpoint between the two points where lock is lost
That was a very blanket statement.
In any circuit where the capacitor is used as a timing or tuning element, the circuit will almost invariably have to be adjusted.
The Service Manual, quite correctly, states that any repair to the Servo Board may require setting up of the board afterwards. Especially if the pots have been disturbed or replaced.
If the caps are simply decoupling or smoothing, then no adjustment will normally be necessary.
Thanks Andy, and greetings Mooly
I guess it would be handy to know for future reference - and anyone else who ever happens to be in the same situation as myself - which caps inside the actual deck could safely be replaced without having to worry about making any adjustments (assuming the unit was working well before!), and those which might well entail having to adjust the unit with an oscilloscope.
Recapping the separate PSU is comparatively simple and only requires a multimeter to adjust two voltages so I'll be able to do that OK.
Mooly: yep I'll leave the internal gain of the Sony WELL alone haha!
I guess it would be handy to know for future reference - and anyone else who ever happens to be in the same situation as myself - which caps inside the actual deck could safely be replaced without having to worry about making any adjustments (assuming the unit was working well before!), and those which might well entail having to adjust the unit with an oscilloscope.
Recapping the separate PSU is comparatively simple and only requires a multimeter to adjust two voltages so I'll be able to do that OK.
Mooly: yep I'll leave the internal gain of the Sony WELL alone haha!
I have a 30+ year old Technics SL1300 with a similar control system and adjustment procedure which had slow speed drift issues. I replaced all of the electrolytics in the power supply and it locked right in without any adjustments other than centering the coarse speed pots. The caps in question are voltage stabilizers which do not critically impact the timing synchronization.
In any case, take great care replacing the caps. As the SP-10 is from the 70ies, it's likely using card boards (paper pcbs) where traces lift off extremely easy. (Not like todays fiberglass boards that are close to indestructible).
Better take great care than repair the traces with wires.
Otherwise, enjoy! Hannes
Better take great care than repair the traces with wires.
Otherwise, enjoy! Hannes
Thankfully didn't manage to lift any traces, and also used a fairly low wattage iron (25w) so that probably helped.
Completely recapped the external PSU and set the voltages for that.
Also recapped two of the boards (the ones with the caps that looked past their best - green legs!). What a swine that was - desoldered the caps OK. But no matter how much I cleaned and defluxed the solder pads the new solder would instantly start 'bubbling' and set whilst bubbling. Had to resolder several caps until I was reasonably happy with the solder joints. Wondering if there's some reaction between the solder and the PCB material or something? Very frustrating!
Still all back together now and appears to be working fine
Completely recapped the external PSU and set the voltages for that.
Also recapped two of the boards (the ones with the caps that looked past their best - green legs!). What a swine that was - desoldered the caps OK. But no matter how much I cleaned and defluxed the solder pads the new solder would instantly start 'bubbling' and set whilst bubbling. Had to resolder several caps until I was reasonably happy with the solder joints. Wondering if there's some reaction between the solder and the PCB material or something? Very frustrating!
Still all back together now and appears to be working fine
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If I wanted to get a simple, basic oscilloscope for setting up this deck properly (which might also help with the odd future project too) would this be up to the task:
Hitachi Battery Oscilloscope V-209 20 Mhz | eBay UK
There's also a list here:
Oscilloscopes
Unfortunately my budget is less than £100...
Hitachi Battery Oscilloscope V-209 20 Mhz | eBay UK
There's also a list here:
Oscilloscopes
Unfortunately my budget is less than £100...
I see the time is ticking...
20mhz is fine for 99% of the stuff in these forums. Dual trace, yes.
The Hitachi V series were good, I used to use a 50mhz bench one as part of the day job.
Given a choice (not sure what this is) you should look for one with a high final anode voltage to the CRT as that gives a bright sharp trace. Something of the order of 6kv or more.
20mhz is fine for 99% of the stuff in these forums. Dual trace, yes.
The Hitachi V series were good, I used to use a 50mhz bench one as part of the day job.
Given a choice (not sure what this is) you should look for one with a high final anode voltage to the CRT as that gives a bright sharp trace. Something of the order of 6kv or more.
Thanks Mooly/Andy
Just realised that that Hitachi is collection only - so I'll have to leave that one.
There's a Tektronix 475 currently for £40 which ends in a couple days so I'll keep my fingers crossed for that (he says, probably having scuppered his chances at getting it cheap by mentioning it on a public forum!).
Having gotten the SP-10 back together again, it's all working fine. Strobe is rock steady on 33 & 45rpm, but I noticed on 78rpm the strobe moves VERRYYY very slightly to the left, and then to the right every couple seconds or so. Perhaps this is normal, though I suspect that I probably do need to re-adjust those pots using an oscilloscope to ensure everthing is absolutely spot on (damn... I hate being a perfectionist!). So really I'll be buying the oscilloscope just for that as I cannot afford to get it serviced.
Just realised that that Hitachi is collection only - so I'll have to leave that one.
There's a Tektronix 475 currently for £40 which ends in a couple days so I'll keep my fingers crossed for that (he says, probably having scuppered his chances at getting it cheap by mentioning it on a public forum!).
Having gotten the SP-10 back together again, it's all working fine. Strobe is rock steady on 33 & 45rpm, but I noticed on 78rpm the strobe moves VERRYYY very slightly to the left, and then to the right every couple seconds or so. Perhaps this is normal, though I suspect that I probably do need to re-adjust those pots using an oscilloscope to ensure everthing is absolutely spot on (damn... I hate being a perfectionist!). So really I'll be buying the oscilloscope just for that as I cannot afford to get it serviced.
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Gould,
Gould OS300 Dual trace 20MHz oscilloscope and probes | eBay UK
Why don't you mark the pot (VR102) and just tweak it slightly left and right. I haven't looked at the circuits for turntable and I might be wrong, but I wouldn't be surprised if it doesn't make much difference until the point where lock is lost
Gould OS300 Dual trace 20MHz oscilloscope and probes | eBay UK
Why don't you mark the pot (VR102) and just tweak it slightly left and right. I haven't looked at the circuits for turntable and I might be wrong, but I wouldn't be surprised if it doesn't make much difference until the point where lock is lost
Thanks for the Ebay link Mooly - I got outbid by a POUND in the last 20 seconds! Arghhhhhh
I'll try for that Tektronix one if it doesn't go sky high.
I would try the pots, but it looks so complicated (judging by the rows upon rows of chips and transistors and the circuit diagrams) I wouldn't want to run the risk of making anything worse. It might actually be spot on as it is, but I have a feeling that slight strobe 'judder' on the 78rpm setting shouldn't be there on this direct drive motor system, and that will translate into flutter when listening... though to be honest I'll probably never play a 78!
You can see how complex a circuit it is here: http://downloads.nakedresource.com/...p?technics/technics_sp10mkii_euro_service.pdf
I'll try for that Tektronix one if it doesn't go sky high.
I would try the pots, but it looks so complicated (judging by the rows upon rows of chips and transistors and the circuit diagrams) I wouldn't want to run the risk of making anything worse. It might actually be spot on as it is, but I have a feeling that slight strobe 'judder' on the 78rpm setting shouldn't be there on this direct drive motor system, and that will translate into flutter when listening... though to be honest I'll probably never play a 78!
You can see how complex a circuit it is here: http://downloads.nakedresource.com/...p?technics/technics_sp10mkii_euro_service.pdf
If you really want a 'scope from E-Bay don't risk bidding for it.
Decide on how much you want to pay as a MAXIMUM price. Don't bid until the last 10 seconds and bid that maximum amount. That takes away the temptation to overbid and will always win against the opportunist bidders who hope to get something for nothing.
If you can risk the last 3 seconds then even better.
Good Luck.
Decide on how much you want to pay as a MAXIMUM price. Don't bid until the last 10 seconds and bid that maximum amount. That takes away the temptation to overbid and will always win against the opportunist bidders who hope to get something for nothing.
If you can risk the last 3 seconds then even better.
Good Luck.
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