SONY TC-355 Tape speed

[JimTekSound]

Hello,

I have a Sony TC-355 that has slow playback. I found that adding tension to the spring help the problem. The idler wheel was dried up and did not have good grip. I sent the old idler in and received a replacement. The unit plays but it is still slow even will added spring tension. When playing a t 3.15KHz test tone tape on this unit the actual frequency is at ~2.90KHz. I fear that the replacement idler may not be the correct diameter. Does anyone know the correct diameter of this idler? Also, what should the RPM of the motor shaft be?

Thanks for your time.

 

[audiojones]

The diameter of the idler wheel will not have any effect on the final speed of the driven flywheel, it is only the diameter of the motor pulley and the diameter of the flywheel/capstan that can change the final speed. Make sure all of the linkages are clean and properly moving into place. The idler linkage is a two piece articulating linkage so make sure both joints move freely or it may slip/drag. Adding spring tension will also add drag, try to put it back where it was or as close as you can get to it. Also make sure the motor and capstan/flywheel bearings are properly lubricated as old gummed up lube can slow things down too. The motor is a synchronous type and is locked to the frequency of the AC line so it's speed can't be regulated, however a bad run capacitor will throw the motor out of phase and slow it down.

If it's still running a little slow or slowing down after it runs for a while you might need a new motor run capacitor. Sony typically uses 2.2uf 250 volt motor caps, you can use a ceiling fan motor poly cap to replace the old can capacitor. The replacement cap voltage can be higher but never lower than the original rating, the MFD (also called UF) rating must be exactly the same as the original. Check your actual capacitor for the correct value rather than depending on the service manual, it may be different.

 

[D'qYdj]

I have the same issue except intermittent. most of the time it runs slow then it will have a good day and run perfectly fine.
pulling my hair out over this. every thing else works perfectly. Record and playback sound fantastic and it's in near new condition.
That's it as my avatar.
I've dis-assembled and lubed every moving part on this thing even removed the head mount and cleaned and lubed the capstan pulley from the under side.
I've replaced the idle pulley between the motor pulley and the capstan pulley and also replaced the motor pulley (new old stock still factory sealed) run capacitor looked
fine, wasn't leaking or anything but I went on to mouser electronics and ordered a new one and installed it. Success! for about 2 days then more of the same...
Any ideas? (cause I'm out). The cap I installed had the same uF rating as well as voltage rating as the original. opps, the replacement is 470 vac but should be fine.

 

[dhnash]

Sonytypically uses 2.2uf 250 volt motor caps, you can use a ceiling fan motor poly cap to replace the old can capacitor. Thereplacement cap voltage can be higher but never lower than the original rating, the MFD (also called UF) rating must be exactly the same as the original. Check your actual capacitor for the correct value rather than depending on the service manual, it may be different.

run capacitor looked fine, wasn't leaking or anything but I went on to mouser electronics and ordered a new one and installed it. Success! for about 2 days then more of the same... Any ideas? (cause I'm out). The cap I installed had the same uF rating as well as voltage rating as the original.

Was the capacitor that you used as a replacement a bipolar type? If not, this could be reason why things worked initially but stopped working after a short period of operation.

 

[D'qYdj]

good question, here is the original cap and the pick label for the new cap I also have a link to the data sheet I don't see
anything mentioning bipoler or not. https://www.mouser.com/datasheet/2/212/KEM_F3063_C87-1101634.pdf

 

[dhnash]

The capacitor you purchased is AC rated for a higher voltage than the original so it should be suitable for this application.