Amazing Sansui CA-F1 Preamplifier Repair and Restoration 

Much appreciated, Bruno.

Multiturn trimmers are really only advantageous where adjustment precision calls for it and the circuit supports it, or where the trimmer value is high and provides relatively coarse adjustment making small adjustments difficult. In consumer gear like this, single-turn trimmers work well in most instances. Circuit stability in consumer gear is relatively poor (compared to lab gear for example) and drift often quickly nullifies any perceived advantage offered by a higher resolution adjustment. Sansui often used a coarse and fine single-turn trimmer arrangement in their amplifiers for example which works very well. People often misunderstand the topic of adjustment, precisely setting a DC null point for example that is by design unstable, only to have it drift by hundreds of mV due to the design! Sometimes trimmer value can be changed allowing for a higher precision adjustment over a smaller range, etc.

@@LiquidAudio hi thank you very much for your extremely kind and valuable advice when i see the complexity of units like this one i am amazed and scared at the same time So many parts to check I have the feeling that in order to get top performance like in this case complexity is a necessity Simpler circuits have no hope to provide for instance these distortion figures ? Last question In your experience which has been the best line preamp you have had on your lab bench ? line preamps are my obessions Kind regards gino

Very reasonable request, I know everyone wants this. The big issue for me is that, being so busy with the business part of what I do, I cannot afford to spend much time on videos. I got a DJI phone gimbal for my birthday, so let's see if I can make my one camera method work better!

It's one of my most frequently asked questions!

Thank you, all analog preamps like this are very rare these days and sound amazing. Sonically these are just fantastic!

Very kind of you John, I stock and use a range of capacitors including Panasonic, Nippon Chemi-Con, Nichicon, Kemet, Elna etc.

Absolutely agreed, thanks for commenting!

No problem. By far the most sensible approach for most is to take equipment like this to a specialist and have it repaired properly. That's my opinion as a specialist working on equipment like this every day, and someone who likes to see equipment like this preserved - liquidaudio.com.au/. Forums and a little bit of knowledge can be dangerous, so just be careful. The service manual does contain a list of all parts including capacitors. Just know that simply replacing parts will not resolve the issues you have there, and may not solve any!

@@LiquidAudio Thanks , am from Chennai and finding specialist is an issue , I myself an electronics engineer and after 30 years just started to do on my own for my amps, last month I did recap my Carver CM1090. and I agree just recap will not solve the all the issue. just a try from my end and will try to find specialist for in-depth servicing.. by the way the manual did not have the full list. Thanks for your quick reply , I appreciate it.

@Senthilkumar Nagabooshanam Excellent, I didn't see this reply, it helps that you are an engineer. I agree, finding good people to do this work is the biggest challenge and partly why I am so busy for example. I have a philosophical problem with the shotgun recap approach and the general 'echo-chamber' around black flag caps for example. That being said, if you take a holistic view and test parts rather than blindly replacing them, that's a great start.

​@@LiquidAudio thanks a lot for your time and I had managed to get the caps list myself ,after continuous effort googling and zooming the shematic's (20mins it did helped. now am a Cloud IT professional for 25years , turning back the clock to 90's where I used to assemble amps and Tv's that knowledge is helping now.

My pleasure, happy to chat.

Hi, different sorts of capacitors for different markets and with hugely different costs in most cases. Nichicon focuses on electrolytic caps, AudioNote focuses on low C film caps, so they can't really be compared when looking at what to use in normal consumer gear.

@@LiquidAudio Thank you for the awnser im sorry but i am not really shure i understand when you say "low c film caps" could you pleas explain this? And just to expand on my cuestion a bit more if you dont mind :) I was thinking mabey of replaceing some caps in my preamp and/or mabey my dac in the output stages and i wonder what brands should use to get a superior sound quality? I understand if this is diffurcult to awnser. Best regards David.

@@zerotoxico No problem, can't get into too much detail in youtube comments but C refers to capacitance and film cap is a type of capacitor. These companies make different sorts of capacitors. To know what parts to use, you really need to understand the role they play in the circuit. Unless you have a good grasp of the engineering aspects of parts selection, it's best to leave that to someone with the knowledge needed to make the appropriate changes and improvements.

@@LiquidAudio Ok that makes more sense now! I am mearly a audiophile trying to learn more about the desingns and im handy around tools so im thinking about doing some easy soldering to start with like changing a potmeter ore trying to clean it more thurogh in my vintage preamp and mabey changeing out some soldering point to AudioNote Solder anyway. Thank you for the reply and please keep up making great video content im learing setp buy step and its grear fun watching 👍

You've gotta love the TM500 series!!

Not from me, plus I don't use parts lists or BOMs anyway. There is a service manual though.

@@LiquidAudio the service manual doesn't have EC list. It has everything apart from Electrolytic caps , I can see only 1000mf 63 v. listed . it says some of the caps and parts omitted in this service manual , and asking to look out common parts list appended to service manual

@@senn6k Correct and my apologies, I saw a couple of ECs and didn't check carefully enough!

So did I (just on my tiny phone)... well I knew it was Sansui because he said. I'd forgotten about Sansui, but yes I had to do a double-take. "Thin pre-amp"? Think Burmester.

@@DuncanWEDD2019 I was going to say it's probably because inside is kept as simple as possible, which is best when it comes to preamps.. But this thing is crammed... Lol

@@playbackvintagehifihunter9669 Yes it does look 'busy'. I noticed that too and I am no electronics expert, sadly (a skill I greatly admire). I have no idea, in truth, and was only glancing at the facia. The more I look, the less the resemblance. But thanks for confirming that I wasn't the only one. Why is this honest, personable and highly dedicated engineer so far away? I can never send away my kit there. The only Dundee I know is where one says "That's not a knife - *this* is a knife. And THIS is a needle!"

@@DuncanWEDD2019 lol! Yes I would like to know there is a engineer like him near me, im UK and they are far ans few in between and charge ridiculous prices.

Hi Tadeo, I'd need the unit here of course for proper diagnosis, but this is a sign of aging components and the need for deep service. Full mechanical cleaning and service is the first step and then tracking down and eliminating any leaky or noisy transistors, replacing bad electrolytic capacitors etc.

Because they don't need to be replaced. Tants are used in some of the most expensive test and measurement gear for a number of good reasons.