Look at the belt, the motor pulley, and the capstan flywheel.
You WILL see there's TWO different diameters that the belt can run on.
One is for 60hz, the OTHER is for 50hz.
Thank you! Notes taken. Do you know this because you have this unit yourself? I’d love to see a photo of CR1, I haven’t been able to find any online and it’d be great to know where it is and how it’s wired exactly. Is the cap non polarized?
Alright! I’ll take a look, sounds simpler than I expected. Thank you for dumbing it down for me, I’m clearly not the expert on tape decks just yet
You don't need a photo. Just look up the names I gave you.
I don't have an Akai, but these components are ubiquitous.
I don't have an Akai, but these components are ubiquitous.
Great, thank you. I'll see if my scrapper has all the parts I need, if not, then I'll get the extra components new.
Anyone has an opinion on this idea?
On another note, I'll surely replace the transistors mentioned by #10 and possibly recap the whole unit with Nichicon FG, at least the preamp board. I don't think this deck has seen many hours of use, but the caps are just too old, maybe it'd be good to replace them preemptively before one fails and it becomes a tragedy.
Thank you all!
Again I will have the contrarian opinion..but...
There are a LOT of electrolytic capacitors in there. Everyone on the forums will always tell you they have to be replaced because they decay after 20, 30, 40 years. But I find that the small value caps don't always go bad. Replacing all the caps on this preamp would be a lot of work, and I think there is a 90% chance you won't notice a difference. You could just replace the six 458 transistors and see whether you like how it sounds. One has to weigh the advantage against the risk of damaging the traces on the circuit board. It can be enjoyable to have a completely restored unit, but you won't be able to replace that preamp board.
If you love soldering and you're very confident at it, and you want to be thorough, then go for it!
There are a LOT of electrolytic capacitors in there. Everyone on the forums will always tell you they have to be replaced because they decay after 20, 30, 40 years. But I find that the small value caps don't always go bad. Replacing all the caps on this preamp would be a lot of work, and I think there is a 90% chance you won't notice a difference. You could just replace the six 458 transistors and see whether you like how it sounds. One has to weigh the advantage against the risk of damaging the traces on the circuit board. It can be enjoyable to have a completely restored unit, but you won't be able to replace that preamp board.
If you love soldering and you're very confident at it, and you want to be thorough, then go for it!
I absolutely agree. My observation is that old (smaller) electrolytic capacitors are more reliable than current ones. And old semiconductors are worse than current ones. PSU capacitors are a different story: measure them and replace if dried out. But I would reformat them before they are deemed faulty.
My relationship with soldering is not one of love, no. I agree with you. Every time old electronics are mentioned, some people say you just have to recap the whole thing. In my experience I've only had to recap three devices, a '69 guitar tube amp, a '91 instrument gauge from a car and a 2000's tv powerboard. I just restored a 70's organ that didn't need a single cap replaced.
I just thought if I got into the unit to do some swaps, I might as well just recap it. However, I've counted 40-something capacitors, so, unless one is really wrong, I'll probably leave it be. I'm not a fan of fixing things that aren't broken, so thank you for the tip!
I agree, PSU caps freak me out a little more, so I might end up just replacing them for peace of mind. They are only 5 or 6 in this board, so it's not a swap of the magnitude of the preamp board. There are a few Mylar caps aswell, but, as far as I know, those are very unlikely to go wrong, am I right?
Thank you!
@fernandito "Every time old electronics are mentioned, some people say you just have to recap the whole thing."
Rarely do complete re-capping something results in any difference.
It's been an INTERNET-BRED 'idiotic' law since the early 2000's due to an issue with a stolen/defective electrolyte formula that turned millions of certain caps prematurely bad.
IT'S OVER, PEOPLE!.
It's no longer a justifiable LAW to keep spreading around the internet.
SO to all you that got brainwashed about that, get over it and move on.
Pass this around to others so that this paranoia can finally stop.
Rarely do complete re-capping something results in any difference.
It's been an INTERNET-BRED 'idiotic' law since the early 2000's due to an issue with a stolen/defective electrolyte formula that turned millions of certain caps prematurely bad.
IT'S OVER, PEOPLE!.
It's no longer a justifiable LAW to keep spreading around the internet.
SO to all you that got brainwashed about that, get over it and move on.
Pass this around to others so that this paranoia can finally stop.
@fernandito
Or on billboards along highways.
Granted, electrolytic capacitors DO tend to age over time.
But much of it is due to the quality of manufacturing (including quality control), and the brand names/vendors.
I've got a Marantz preamp on the bench now, after repairing a matching Marantz power amp.
Both were manufactured around 1969/1970, and contained the same blue colored capacitors, which now have obvious dry-rotted rubber seals, and need replacing.
Mind you, both units still work - they don't blow up or cause worldwide terrorism, alien abductions, or covid 19 sickness.
But they do require replacement now.
And that is a reasonable, yet tedious task.
But likely someone, sometime, somewhere, posing as a self-endorsed crusader of mankind came across one of these Marantz products, and decided to flood the internet with.... "Oh my god!, jeepers!, I have to warn the world that every stinking capacitor in every stinking product needs replacing or else!"
HOWEVER....
After 40 plus years of being a professional audio/video servicer, and knowing quite a few others in the field, all of us with plenty of experience know about this internet-driven nonsense, and we laugh about it.
That's right, we laugh at you paranoid idiots!
Because WE know better.
Our feet are on the ground in reality, not brainwashed due to something someone said on the internet.
Or on billboards along highways.
Granted, electrolytic capacitors DO tend to age over time.
But much of it is due to the quality of manufacturing (including quality control), and the brand names/vendors.
I've got a Marantz preamp on the bench now, after repairing a matching Marantz power amp.
Both were manufactured around 1969/1970, and contained the same blue colored capacitors, which now have obvious dry-rotted rubber seals, and need replacing.
Mind you, both units still work - they don't blow up or cause worldwide terrorism, alien abductions, or covid 19 sickness.
But they do require replacement now.
And that is a reasonable, yet tedious task.
But likely someone, sometime, somewhere, posing as a self-endorsed crusader of mankind came across one of these Marantz products, and decided to flood the internet with.... "Oh my god!, jeepers!, I have to warn the world that every stinking capacitor in every stinking product needs replacing or else!"
HOWEVER....
After 40 plus years of being a professional audio/video servicer, and knowing quite a few others in the field, all of us with plenty of experience know about this internet-driven nonsense, and we laugh about it.
That's right, we laugh at you paranoid idiots!
Because WE know better.
Our feet are on the ground in reality, not brainwashed due to something someone said on the internet.
@wiseoldtech well said! I’m more of a guitar tech guy, but I get my hands on electronics for myself or friends and my experience has also been that capacitors are not faulty often at all. I’m sure time itself causes them to fail if they’re not well manufacted, as you mentioned, but I believe hours of use is much more of an indicator of how much the capacitors will be operating correctly. I feel like most audio gear from 50 years ago has been unplugged 99% of the time since manufactured.
About the Akai, I got a voltage converter while I figure out the mod and get the parts, just to check overall condition.
Mechanically, the take up reel shaft is slightly bent, but it seems to work ok. The capstan wheel doesn’t pinch the tape unless you push it a little and then it stays in position, probably fixable adding some tension to the levers or springs. I’m missing the little screw-on bike-wheel-kind cap for the speeds, which I’ve read is necessary to keep it at speed. The speed cylinder is there in fact, although it’s impossible to remove by hand (I eventually will with some pliers, clean out rust and lubricate)
Sound wise, monitoring source works for both channels and so do the VU’s. However, I can’t get it to monitor tape, record or playback. I tried those functions via headphones out only yet, as I haven’t had the time to plug it into an stereo out. The heads don’t look brand new but they look ok to me. Changing from Stereo to 1-2 or 3-4 does a little cough sound and channels seem to be a little out of balance for now, probably easy to fix with the trimpots.
I will post pics in a few days when I’m back home so I can get some more input. Meanwhile, a really dumb tape question... Is the tape a one side only thing? Meaning, is there one side of the tape that essentially works and the other is just plastic coated and won’t play or record anything?
I’m new to tape, please don’t stone me yet 🙂
Thank you!
About the Akai, I got a voltage converter while I figure out the mod and get the parts, just to check overall condition.
Mechanically, the take up reel shaft is slightly bent, but it seems to work ok. The capstan wheel doesn’t pinch the tape unless you push it a little and then it stays in position, probably fixable adding some tension to the levers or springs. I’m missing the little screw-on bike-wheel-kind cap for the speeds, which I’ve read is necessary to keep it at speed. The speed cylinder is there in fact, although it’s impossible to remove by hand (I eventually will with some pliers, clean out rust and lubricate)
Sound wise, monitoring source works for both channels and so do the VU’s. However, I can’t get it to monitor tape, record or playback. I tried those functions via headphones out only yet, as I haven’t had the time to plug it into an stereo out. The heads don’t look brand new but they look ok to me. Changing from Stereo to 1-2 or 3-4 does a little cough sound and channels seem to be a little out of balance for now, probably easy to fix with the trimpots.
I will post pics in a few days when I’m back home so I can get some more input. Meanwhile, a really dumb tape question... Is the tape a one side only thing? Meaning, is there one side of the tape that essentially works and the other is just plastic coated and won’t play or record anything?
I’m new to tape, please don’t stone me yet 🙂
Thank you!
Yes, that's how it works. One side has the magnetic material and the other side is the plastic backing.
Prying the 7.5ips collar off with pliers will ruin it, period.
The record/play switch inside is likely now tarnished and in bad need of cleaning, as are the other switches and pots.
This unit is in bad shape and has been abused since tape spindles are bent.
Honestly, I'd consider it a parts unit and wouldn't even bother repairing it, because there are many other 4000's out there for sale.
The record/play switch inside is likely now tarnished and in bad need of cleaning, as are the other switches and pots.
This unit is in bad shape and has been abused since tape spindles are bent.
Honestly, I'd consider it a parts unit and wouldn't even bother repairing it, because there are many other 4000's out there for sale.
I agree. Unfortunately, many times it is left in a damp garage or basement for about 49 years 😒
Again, this site is called DIY audio, not buy-a-brand-new-component-in-perfect-condition audio. You're free to embrace the challenge of tinkering with it to get a device that will do something you like. Obviously this is not your hifi music playback device in 2023.
The bent shaft happens, can be bent back gently and isn't as bad as it looks. You will need to clean out the dried orange grease inside and then things like the pinch wheel mechanism will move better. If the capstan sleeve for 7.5ips is there, leave it, no point in using low speed - the rust will help it grip. 🤣 If it's missing the nut, you can use another 2mm nut of approximately the right thread size, also similar story for the pinch wheel cap.
If you don't have tape playback audio, check whether that part of the preamp board is getting its 24v power. Channels will have uneven levels because of the bad old transistors mentioned above. You can calibrate them with the trim pots but likely one will have worse signal to noise for that reason, until you replace the transistors, because you're just compensating with gain. Does it not record, or just can't monitor tape while showing recording on playback VUs?
If you buy another deck, you're likely just buying a different set of problems to overcome.
I'm not sure if fernandito is still visiting this forum ?
I'm using his thread, I hope it won't bother him.
I got an akai 4000DSMKii
The original LET-18 transformer is down.
I found another LET-17 transformer.
According to the above schematic can I swap one another ?
Here is the mod list :
-remove wires from pin 3 and 4
-connect motor cap to pin 2 (2 pins)
-move tension switch between pin 1 and 2
-add CRI 0.1+120/300W.V (should I buy another one ?, mine is 0.033+120/300W.V)
-add a ground wire ?
Thanks
