Hi do you think I should replace the caps in My aiwa tp 40 RtoR because lately it sounding funny and the batterys are fine

here is a generic picture of one

"sounding funny"...how? Need more of a description! There probably aren't that many caps in there to begin with, so it wouldn't hurt to recap it anyway, at this point.

If it's a rim drive (as apposed to capstan drive), it will always sound funny. Like the speed is not regulated, because it's a rim drive model.*

*Edited that last sentence, because it didn't make sense at first. Now it does.

OK, I looked into it, and that is a rim-drive model. Personally, I never liked those kind. You're better off with a capstan drive one, but if you like it, then...what can I say? Anyway, if there are fresh batteries in it, and the sound is weak coming out of the speaker:

1. Clean the tape recorder head with high quality isopropyl alcohol (91% is available at Wal-Mart, anything less is not good) using a Q-Tip, and see if that helps.

2. Check to see that the tape head is not worn out.

3. How is the volume control? Maybe a squirt of cleaner needs to be used. Also, check the play-recording switch to make sure it doesn't need the same.

4. If all else fails, it's probably the capacitors.

Good Luck!

how do I check the tape head. I did clean the head and the battery's are ok on My meter

replacing caps is easy so I can replace them

this is no cheapo tape recorder this has PP 2sb61 output. here is the cap list

1 30mf 10v
2 10mf 6v
3 5mf 6v
1 3mf 12v

should I go with all 16v caps on this one

"how do I check the tape head."

with a good magnifying glass, u can look for any obvious signs of damage, especially at the gap.
Sometimes head needs azimuth alignment to optimise.
But I wouldn't mess with any aligments unless I was positive it was out of alignment (ie - upon head replacement),
and had a proper alignment tape.
agree, it would be helpful to be able to hear an audio sample of what "sounds funny".
can you make a video recording say with a phone or sumthin? Then upload someplace like
youtube, dropbox, google docs where other people can hear it.

here is a pic of the underside

amp pic EDIT those resistors are odd

It has PP output because it is Class B, just like almost all transistor radios of the period. That is a very cheap tape recorder -- millions were sold under several brand names in the 1962-64 period for under $20 when a "real" portable tape recorder (capstan drive) was $150. These were sold as children's toys. I remember them well. My two younger brothers both had them.

Personally I wouldn't put any time into it. It will never sound good.

-David

oh but I like it and this is one of the higher quality ones so I am going to replace the caps

Those resistors are the normal "dogbone" type that they made over in Japan back then. If you liked the recorder before it started "sounding funny", it will probably sound better after the recap. The caps won't cost you very much (low voltage type=least expensive to buy), and there aren't that many to do, anyway. They are due to be replaced by now, like I said. Hope that solves the problem for you...good luck!

Believe it or not, you could have bought a fairly cheap capstan drive model, back when this was made. They had them. Mono unit, made for Radio Shack (Realistic) in Japan...I think, and cost $64.88 in their 1964 catalog. This is a big step up from your Aiwa:

For $29.95, you could buy a Panasonic capstan drive, in 1967 (Radio Shack catalog):

On your Aiwa, there is one critical resistor, that provides DC bias to the head during recording
only, and if open, the machine will record but the sounds will be blotchy and distorted.


Your machine is a very solidly built specimen of a 50 year old Japanese product; Someone may
want it for a collection.

what is the resistor value so I can test it if bad I will replace with 1% precision type. I am going to keep it

I do not have the schematic for your tapre recorder, however here is a schematic, which will
be very similar. The bias resistor is at the bottom and is 25 K.

You should not change your resistor until you understand that this is the problem.

I think I will keep it original and just have it as a novelty in My radio collection

do I need the exact mike because I have using a speaker as a mike

In these machines, the two problem areas are germanium transistors developing 'tin whiskers' internally (google it) and the electrolytic capacitors, which lose capacitance, go leaky or go high ESR over time, if used or not.

Start by changing the caps on the audio output stage, they're cheap and easy to find, then try and find silicon equivalents for the output transistors if you still have low audio.

In terms of mic, you need a 'dynamic mic' of 200-300 ohms impedance. Using a speaker will get you atrocious recordings due to the diaphragm being far too insensitive, coupled with the limitations of the machine. In fact, I'm amazed it works for recording at all.

These machines are not constant-speed units and so unsuited to music. They are designed pretty much for speech/ dictation but are great fun (I have an Aiwa TP50 , I think thats the model - needs the amp overhauling just like yours!)

where can I get a 200 ohm mike

I'm pretty sure I saw them new in a branch of Radio Shack when visiting the US 2 years ago. They crop up on ebay too. Often used with 'shoebox' cassette recorders, especially the type with the leatherette cases (journo style) so keep an eye out at flea markets , antique palces, etc.