Simon Minstrelle

[DMcMahon]

Powered up just the tape deck direct from the mains with a 1 amp fuse in the mains 3 pin plug and monitored the current.

Both motors working OK.

Just powered up, the drive motor runs continuously and rotates the flywheel nicely via the intermediate rubber idler wheel, current drain is around 90 mA.

In Play and Record modes (no tape fitted) the current drain increases to around 128 mA and Take Up spool is driven in low power (low speed) mode.

In Wind mode (no tape fitted) the current drain increases to around 260mA and Take Up spool is driven in high power mode (high speed).

All 3 current drain figures above are lower than values listed in the Garrard manual (which are 110mA, 150mA & 290mA respectively), I expect the actual current drains to increase somewhat when driving a tape.

I was about to load the tape magazine but did another Wind test and as soon as I pushed the switch towards Wind, it blew the 1 amp fuse in the mains plug.

Motor windings continuity is good and Meggar OK to ground. There is a click suppressor device wired across the Tape Up motor low power (low speed) switch contacts, which on the schematic is shown as a series CR transorb (0.05uF + 220 ohms). The fitted device is a potted Hunts ZX250.

Am wondering if the transorb could be intermittently breaking down and causing the fuse to blow. Would be nice as would be an easy fix. I will remove it and replace with a new transorb once I remember where I have a couple of spares stored.

Cleaned up rusty capstan shaft. Managed to remove some of the unsightly rust bubbling on the deck white paintwork. Cleaned the heads.

[terry123]

Hi David , making good progress with this . Change or restuff though , these cause no end of issues. They can quickly breakdown when frightened with mains, and get very hot in the process.




Terry

[DMcMahon]

Hi Terry, I am definitely not into restuffing, for me personally little point in the extra time, if item is internal and not normally seen. Also as this is a potted item, probably extremely difficult to get inside it without wrecking it.

Struggling at the moment to find my spare transorbs, will probably have to make one from a normal X2 filter capacitor plus resistor.

David

[unitelex]

I have some GE V275LA15A varistors, NOS
You are welcome to one of these for the cost of postage

Pic here: https://wellgainelectronics.com/vari...v275la15a.html

Best Regards
Chris

[DMcMahon]

Chris thank you for the offer, I think I will be OK though.

Have not yet found my spare transorbs but I have removed/borrowed one from my Grundig TK 819, will fit this to the Garrard deck later. Meggered the old Hunts transorb and it was pretty poor, 30kohm at 50V and down to 10kohm at 500V.

Do you find the varistors do a good filtering job and are they more immune to damage ?

David

[unitelex]

Originally Posted by DMcMahon

Chris thank you for the offer, I think I will be OK though.

Have not yet found my spare transorbs but I have removed/borrowed one from my Grundig TK 819, will fit this to the Garrard deck later. Meggered the old Hunts transorb and it was pretty poor, 30kohm at 50V and down to 10kohm at 500V.

Do you find the varistors do a good filtering job and are they more immune to damage ?

David

Hi David,
10K Ohm at 500V won't be great at absorbing transients IMHO.
The metal oxide varistor would be much better and good enough for the application. Semiconductor transient suppressors have an even sharper clamping effect but probably not necessary for this application.

You can often salvage good MOVs from the input stage of a modern Switched-Mode PSU, a good brand, not the cheaply built asian ones.

Best Regards
Chris

[DMcMahon]

Fitted the transorb from my TK 819 to the Garrard tape deck. The transorb is a Kemet (Rifa) PMR209 which as I covered in my TK 819 Thread I was not that happy to use at that time because they are only rated at 250 Vac (but are X2 safety rated) and are Metalised Paper, higher AC voltage rated Metalised Polypropylene versions being hard to source and expensive.

The transorb insulation resistance measured > 2G Ohms (after initial 200M Ohms kick) when checked on the Megger at 500 volts.

The replacement transorb would have been too large length wise to fit in the old transorb body (without removing one end panel) but I did try to open up the old Hunts transorb with the idea of removing one end panel and gluing the replacement inside so I could utilise the hold down screw that secured the old transorb down.

But the potting compound was like hard rock and the transorb case just fell apart when trying to break through the potting compound.

After loads of motor operations the fuse blowing looks fixed.

On Wind (Fast Forward) there is an issue where towards the end of the tape (on both sides) Wind struggles and comes to a stop. It looks like something is binding up in the tape magazine.

Next will try the tape magazine tape/spools without the magazine being fitted plus try standard tape spools.

[DMcMahon]

With the tape/spools removed from the magazine and refitted to the deck, Wind then works fine.

Only small thing I found with the magazine was a small build up of tape oxide on the 2 metal tape guides which I cleaned off, which has helped a lot. If the Wind button is held to the end of Wind (operationally you have to manually hold it in position) Wind works fine to the end of the tape. If you stop the Wind very close to the end of the tape then Wind may still struggle a bit, strangely Play does not, but I can live with this.

The metal tape guides in the magazine are fixed (do not rotate), which must create extra friction.

Next to refit the tape deck back into the chassis, reconnect the wiring and see if any sound obtained on Playback.

[DMcMahon]

While refitting the tape deck, the inputs panel got knocked off, its wooden mounting block that was screwed and glued to the thin plywood frame broke away.

So had to remove the deck to be able to clamp down the block after gluing it back on.