Hitachi TRK-7620

[Tazboomboxowner]

So yesterday, I came across this Hitachi unit and it looks as if it has been out in a shed for a few too many years.

Anyway, I am trying to get a scan of the service manual, dose anyone have it as a PDF, a copy would be great.

I did have a few questions:

• What is the safest way to clean the dust off the speakers.
• Can I use an air compressor to blast most of the dust off.
• The tape deck dosen't play, anyone know the type and size belt or a belt kit I can buy?

Thank you in advanced for any answers.

A few snaps of my unit.

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[MyOhMy]

Jeez, if when you fix that you deserve a great big pat on the back. Where had it been abused all these years? It looks to me as if it was stuck in the corner of a dumpster for years whilst the dumpster was refilled over and over again!

 

[BassHead]

I clean speakers with a soft paint brush, and pull off debris with tweezers....very carefully! It takes a little time, but worth it. Do it over a beer and it will go quicker.

Canned air works...but I wouldn't do it on the speakers.

 

[Reli]

If you really want to do the best job, take the boombox apart and remove the metal grill. It's usually not very dificult. Then put it back on and use hot glue on the tabs.

 

[MyOhMy]

Can we have a blow-by-blow account, with as many pics as you can, of the resto and are you taking bets on what DNA may lurk on the exposed surfaces or what forms of expired critter life lay within?

 

[Northerner]

Needs a bath!

 

[MyOhMy]

Needs a bath!

Only you could say this so early I can just image you thinking of bathing that BB.............

 

[Northerner]

Lol even the clean ones get a bath so this mucky pup certainly would. Saying that, I did have a 7620 that didn’t! But then it was mint in the box and didn’t need anything doing to it. It was genuinely like new

 

[Stuzy]

Calling international rescue seen worse though.
Look forward to seeing them done

 

[Helmar]

Hi,
I today finished the restauration of a 7620, my now 8th Hitachi 3D.
Your unit looks good, cleaning is the easiest kind of repair.
You need to take it fully apart and give all plastic parts a bobble bath.
Clean the speakers with a soft paint brush as said before.
The tweeters are glued into the front - remove them very carefully.
You do not need to remove the speaker grills, only the front panel where all speakers are mounted.
Belts: there are sets of 30 belts available on eBay (coming directly from China).
Take the best fitting one and adjust the tape speed afterwards.
You also have to take a look at the clutch for the idler gear.
Clean all switches and pots with contact cleaner and clean the main board with compressed air.

If you need more help, let me know. The 7620 is easy to service.

Best regards
Helmar

 

[Tazboomboxowner]

Jeez, if when you fix that you deserve a great big pat on the back. Where had it been abused all these years? It looks to me as if it was stuck in the corner of a dumpster for years whilst the dumpster was refilled over and over again!

Can we have a blow-by-blow account, with as many pics as you can, of the resto and are you taking bets on what DNA may lurk on the exposed surfaces or what forms of expired critter life lay within?

MyOhMy it looks like this unit was left in a shed for a few too many years, for now I can not see any rust, but on the inside, I don't know.

I am intending to do a restoration video, so I will not be posting photos I am afraid, just my lame attempt at a video.

---

If you really want to do the best job, take the boombox apart and remove the metal grill. It's usually not very dificult. Then put it back on and use hot glue on the tabs.

I clean speakers with a soft paint brush, and pull off debris with tweezers....very carefully! It takes a little time, but worth it. Do it over a beer and it will go quicker.

Canned air works...but I wouldn't do it on the speakers.

Thank you for that, I do still have a bit of canned air left.

I think I will have to pick up some hot glue sticks today, I am sure once white ones go yellow, they are best not used.

---

Hi,
I today finished the restauration of a 7620, my now 8th Hitachi 3D.
Your unit looks good, cleaning is the easiest kind of repair.
You need to take it fully apart and give all plastic parts a bobble bath.
Clean the speakers with a soft paint brush as said before.
The tweeters are glued into the front - remove them very carefully.
You do not need to remove the speaker grills, only the front panel where all speakers are mounted.
Belts: there are sets of 30 belts available on eBay (coming directly from China).
Take the best fitting one and adjust the tape speed afterwards.
You also have to take a look at the clutch for the idler gear.
Clean all switches and pots with contact cleaner and clean the main board with compressed air.

If you need more help, let me know. The 7620 is easy to service.

Best regards
Helmar

Would Isopropyl alcohol act as a good contact cleaner?

I might have to take you up on that at some point, thank you.


---

Okay, so for now I have a good idea of what I need to do.
I didn't know I could just dunk the case into a tub of warm water or to clean the speakers, I just use a pain brush (carefully).

My shopping list for now is:

• Car detailing took kit. (Just in case)
• Service manual $13 USD (More because I am Australian) https://www.analogalley.com/osccart/product_info.php?products_id=2090
• And new hot glue sticks.

Thank you again everyone, this will be taking me a few weeks to fully collect and I will try to keep this topic updated as I go.

 

[jimmyjimmy19702010]

Your Hitachi is a first series 3D so the grills will be removable but personally, I wouldn’t bother - it’s tonnes of work and plenty of risk of the grills being damaged in the process.

You can get the grills perfectly clean without removing them.

 

[Reli]

I didn't know I could just dunk the case into a tub of warm water or to clean the speakers, I just use a pain brush (carefully).

Remove the speakers first though.

There's basically 2 choices here:
Remove the front case and then remove the grill, and just brush/wipe the dust away.
Or, remove the front case, remove the speakers, and dunk the case.

There are some people who leave the speakers in when they dunk it, but I don't agree with that

 

[neanderthal]

Id start with a vacuum cleaner t be honest.

 

[Helmar]

With regard to your shopping list:

Instead of car detailer you can take tooth brush for carefully polishing the box (after the bath).
I would first take a look at the service manual from sister models like trk-3d8 oder 3d70 which are similar enough to get an idea how to do the teardown.

https://elektrotanya.com/showresult?what=hitachi%20trk-3d&kategoria=&kat2=all
or
https://www.hifiengine.com/manual_library/hitachi.shtml?category=portable-system

It is personal taste, but after studying the other service manuals, you do not need more literature.
For the bobble bath of the plastic parts you need to remove every screw anyway.

Hot glue? Always good to have in the background, but apart from the dust/dirt, your machine seems to be in good shape (nothing to glue/repair).

Best regards
Helmar

See a picture from last Wednesday. Box before putting it back together - with some small modifications, bluetooth etc.

 

[Tazboomboxowner]

With regard to your shopping list:

Instead of car detailer you can take tooth brush for carefully polishing the box (after the bath).
I would first take a look at the service manual from sister models like trk-3d8 oder 3d70 which are similar enough to get an idea how to do the teardown.

https://elektrotanya.com/showresult?what=hitachi%20trk-3d&kategoria=&kat2=all
or
https://www.hifiengine.com/manual_library/hitachi.shtml?category=portable-system

It is personal taste, but after studying the other service manuals, you do not need more literature.
For the bobble bath of the plastic parts you need to remove every screw anyway.

Hot glue? Always good to have in the background, but apart from the dust/dirt, your machine seems to be in good shape (nothing to glue/repair).

Best regards
Helmar

See a picture from last Wednesday. Box before putting it back together - with some small modifications, bluetooth etc.

I think you must miss understand the car detailing kit, I have had my eye on it for a while now and it was not the brushes, but the rubber nobs I am wanting, here I will link it, https://www.ebay.com.au/itm/202292077290

So for the service manuals, do the TRK-3D8 and TRK-3D70 use the same cassette module?

I see the front mesh is just bent into pace, that will make things easier, thank you.

 

[Helmar]

Ok, now it’s clear.
The deck units are not identical, but similar (and a simple construction) - for changing the belt you have to remove one screw in order to get access to the flywheel.