Advise on tape deck

[rhomanski]

I'm working on the cassette deck I bought in 1985. A Sansui DW-10, the belts finally started slipping so I had to open it up. Here's the service manual http://www.hifiengine.com/manual_lib...ui/d-w10.shtml . While I was changing belts I thought about how old the caps were and decided to replace them.

I'm on the record/play amp now. Specifically around IC4, the volume control chip for playback/rec and double speed dubbing. If you look at the CR input, pin 12, you'll see it goes back to the collector of Q2, and Q3. Through C4 and C5, which look like DC blocking caps. I looked at the spec sheet for the chip and it looks like it takes 11 volts max although it was in Japanese. The question is the two caps are 100 volt Elna's, I have 50 volt in hand. I think they'll work just fine. Does anyone think I should order 100 volt? I know 50 is as small as you can get those values today and I'm thinking 100 was the smallest available in 1984. Does that sound right?

Thanks for your time.

[TechGeek]

Re: Advise on tape deck

I would measure the input voltage to those caps(last trace before caps) and if it's somewhere close to 100VDC, get 100VDC caps. 50V caps would grenade on 100VDC.

[rhomanski]

Re: Advise on tape deck

Thank you for the reply, but it's in pieces right now. It took me two days to tear it down and would take the same to put it back together. It's a very complicated deck. The main board I'm working on has about thirty ribbon cables and probably 300 wires total. It's hard to get to some of the caps because of all of the cables.

[stj]

Re: Advise on tape deck

before you chew any tapes - check the pinch rollers.
those cause far more problems than the belts.

[SteveNielsen]

Re: Advise on tape deck

Service manual only available to registered users from that site. Post it if you have it downloaded.

Shelf life on some rubber-like products is no where near 31 years and since no one knows what the belts and rollers are made of it might be a good idea to replace them all if you can.

[rhomanski]

Re: Advise on tape deck

Good advice, the pinch rollers are still good. The belts are shot. It has one flat belt for each well, gears for the rest. That's why it lasted so long. I've got the new belts on the mechs, I just need to know if someone sees something I don't in the schematic. I don't see how the transistor could have anywhere near 100 volts either AC or DC. I think that was the lowest voltage available for an electrolytic in a .22uF in 1984. I've seen it before in other gear but that was made in the seventies. It was also a low noise cap. I used a 50v in that one and it was fine. I'm not sure if 50v were available in the eighties. It's an Elna 0.22 uF 100volt RE series I think. The other is a 0.33uF 100volt Elna. I've got 50v KL Nichicons I can use there. Just wondering if anyone sees a problem if I do it.

[rhomanski]

Re: Advise on tape deck

here's the manual maybe, ahh, looks like it went through.

[stj]

Re: Advise on tape deck

.22 is obsolete, even .47 is hard to get decent brands and 50v is minimum.
i'd use a polyester or ceramic myself.

[rhomanski]

Re: Advise on tape deck

I looked at Elna's offerings now, they have a RE3 line which is general purpose. I don't know if they're the same as the old RE series. They only go down to 1uF at 50 volts. I got some Nichicon KL series last year at .22 and .33 50 volt. I was planning on using them, but they also have the same at 100 volt. I would have to order them though or any other kind. It would save me money to use what I have since it costs about $10 shipping for 2 day delivery from Mouser.

[SteveNielsen]

Re: Advise on tape deck

Schematic label says IC4 as LA-7530 but it's not, it's LC-7530 and that threw me for a loop (at least the parts list has it right). I can't see anything in that part of the circuit that would be above B+ which is 12.8v but it doesn't help that the spec sheet for that chip is in Japanese (as you said). I bet 50v caps would be fine.

[rhomanski]

Re: Advise on tape deck

Yeah, that got me too. I didn't see any reason not to use it but wanted a second, or more, set of eyes on it. Appreciate all the replies, I'll carry on with the 50 volt KL's I have here.

Sansui schematics are notorious for being different. So many revisions and none documented.