JVC HRD170/FERGUSON 3V65/Thomson V510 belt change

[ben]

On a tangent from a recent thread.
I have noticed that this late 1980s deck sometimes jams in unlace. There is a small loading belt on the underside which moves the worm gear and cam which is past its best. However, access means removing the whole plate to which the load motor, cam, etc. seems to be attached.

The service manual gives no suggestion on the belt replacement procedure (considering this is probably the number one repair in a VCR: why??!). A quick search of the TV mag database gave nothing either.
I don't want the whole thing to go out of alignment if I can help it. I have put an elastic band round the load arms and removed three screws from the plate. However there are clearly spring-tensioned linkages lurking nearby, so thought I'd check here before proceeding. TIA.

[dj_fivos_sak]

Hi. I've never worked on one of these, but I'm assuming the retaining plate (the one with the "360910" marking), needs to come out. After doing that, the belt should be easily accessible, as well as the mode encoder switch. It would be a good idea to clean the internal contacts of the switch while you have the machine apart.

Fivos

[ben]

Well, I decided to have a go.

The worm gear which the belt drives is held in by a c-clip on its shaft. This then enables you to push the shaft back and slip the belt through - in theory. In practice, there's so little clearance that you have to apply some pressure with the blade of a screwdriver to make this possible. (pic 5)
Getting the new belt in was a similar faff. There's also a grey wire from the pcb on this assembly (just visible in pic 1) that limits your movement unless you unsolder it, just like the early 2000s funai junk.

Reassembled and all the thing now wants to do is rewind without a tape in. Have tried shifting lever /folllower (indicated by screwdriver shaft pic 4) in a few positions to no avail (I had marked the position of the main cam but that served no real purpose).

So unless I come across the required information/diagrams this unit looks like another for the scrap pile thanks to a truly idiotic design (and coupled with a useless service manual) for what is a bread and butter servicing task!

Attached pics in case anyone else is brave enough to ever attempt one of these.

[Red to black]

Hi Ben, there is not usually any problems when timing this deck as there are only a couple of alignment holes in the main cam, sector gear/loading arms and main deck to align, I used to use a couple of jewellers screwdrivers to help with this.

The JVC HRD170 manual has enough info. This machine is also sold under the Fergy FV11R, a few of the early Fergy FV decks are the same.

Most loading problems on this deck was due to the very thick black grease on the sliding metal parts going hard and very sticky.

[vhs doctor]

Hi Ben

Check by hand or using a flat screwdriver to load and unload the mechanism the V mark on mode selector switch and metal plate must be aligned. If your mechanism blocked during loading or unliading you have wrong position in metal plate.

I have done the procedure a lot of times in past. The problem is that when you lift the loading motor mechanism the metal plate moved due to a spring and became misaligned.

In my opinion it is a reliable mechanism due to direct drive in basic motors such as capstan and reel.

[Red to black]

Yes, not a difficult machine to re-time, JVC helpfully put holes in the deck plate and sliding parts as well as the main cam to aid alignment, I found this mechanism fairly reliable apart from the loading belt and the grease going sticky, not a bad deck to work on.
The screw that holds the terminal board to the upper loading/cam gear part (viewed from the bottom) is also the chassis return for the deck sensors etc.and did cause a few problems as it became slack due to the solder pad creeping under mechanical pressure of the screw, I used to fit a serrated/star washer here to stop the problem recurring, it might have even been a recommended mod but I cannot recall.

[ben]

Thanks to Red to black for the info, I have now set up the timing. The main problem was the plate assembly being out of position (it needed some slight tweaking just as the cam bracket assembly was refitted, to seat it fully). I had also been looking at the wrong holes (!) in the plate.

I also added a drop of light oil to the spool table shafts/bearings, as winding was rather noisy. I may have to do the same to the drum motor if I can remove the rather stubborn screws on the bottom rotor to gain more access.

[Red to black]

Glad you got it sorted Ben, they used one of the better decks, all metal for the most part.
The SM is a bit sparse on details compared to earlier decks, I suppose it was a 'given' on how to replace the loading belt once armed with the timing info.