UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players

Notices

Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

Closed Thread
 
Thread Tools
Old 28th Jul 2020, 6:00 pm   #1
RetroRichard
Triode
 
RetroRichard's Avatar
 
Join Date: Feb 2020
Location: Maidenhead, Berkshire, UK.
Posts: 12
Default Shims for Philips N4404 speed correction

Hello, I thought the following info about speed adjustment shims on the N4404 tape recorder might be useful to some.

I have recently been renovating my old Philips N4404 (bought new around 1968) and have done some speed testing using a spreadsheet calculation including input of the time to complete 20 turns and the thickness of the tape (1.4 thou). The results agreed with an old 10 minute accurate timed recording and showed that even after replacing the two main drive belts, the 3.75 inch/sec setting was still running about 1.6% fast.

The original long V-shape belt around the pulley is no longer available so I have replaced it with a 2.6mm diameter round belt which seems to work very well.

For those who want to do an adjustment, the pulley that is fitted to the main motor shaft is in two parts, with thin shim washers in between the two parts. Adding a 0.2mm shim reduces the speed by about 1% I think.

After removing the leaf spring and screw that rest on the little plastic cap at the top of the motor pulley, and unscrewing the two small grub screws that fix the pulley to the shaft, the whole pulley can be pulled off of the shaft. Using a 10mm AF spanner at the top and a 14mm AF spanner at the bottom, unscrew the bottom collar. The original shims were 8.2 mm ID and 10.5 mm OD and about 7 thou thick. I could not find those exact dimensions on the internet but did find that Screws City Ltd on ebay) sell 0.1mm and 0.2mm thick shim washers of size M8 ID and 14 mm OD. I fitted a couple of extra shims and found that the extra diameter did not cause any problem as the belt does not go down the groove enough to touch the new shim edge.

Hope this is some use to any N4404 owners still out there.
Cheers
RDA
RetroRichard is offline  
Old 28th Jul 2020, 6:36 pm   #2
DMcMahon
Dekatron
 
DMcMahon's Avatar
 
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,587
Default Re: Shims for Philips N4404 speed correction

Hello Richard,

Not familiar with Philips much, some very good detail in your Post, a few photos would help to explain it further.

David
DMcMahon is offline  
Old 29th Jul 2020, 12:35 pm   #3
ricard
Octode
 
ricard's Avatar
 
Join Date: Mar 2006
Location: Lund, Sweden
Posts: 1,631
Default Re: Shims for Philips N4404 speed correction

It would seem then that this fine speed adjustment is something intended by the manufacturer and not just a happy coincidence?
ricard is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 5:42 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.