Sharp GF-508ST low volume and no LED in left ch

[Mota74V8]

Hello!
This is my first post.
I just bought a Sharp GF-508ST, apparently never repaired before.
The left channel volume is too low in stereo mode. And the left channel LED doesn't work when playing, but turns on when I check the battery level.

The sliders are OK
The right side works fine.

Can anyone help me find out where the problem is?
I also need a service manual. Can someone send it to me?

Thanks,

Mota.

 

[BoomboxLover48]

It was a bad solder with my unit.

Check the following thread.....

Sharp GF508 no sound at all. | Boomboxery

Royce

 

[BoomboxLover48]

See the bad solder joint next to the plastic tie. That was the bad solder joint causing the problem with the LED VU meter malfunction and sound with one channel. You have to get to the back side of the PC board to locate it.

 

[Mota74V8]

Today I changed the belts and cleaned the tape drive. The "capstan" was locked!
Tomorrow I will disassemble the main board and check the solders.
I'm connecting the 508 to the 127v voltage in my country, which doesn't have 100v. This will be a future issue for me to fix. I'm considering the idea of buying a 15v charger and putting it in the battery compartment.

Later I will share the results.

Thank you for your help.

 

[Mota74V8]

Hi Royce
I was looking for bad solder. I smelled burning. The IC uPC1185H (1) on the left side burned out.
I found uPC1185H2, but I don't know if it's the same as uPC1185H.

I really need the 508ST service manual. Can you send it to me please?

Thanks,

Mota

 

[Superduper]

NOBODY has that service manual. That is a Japan only model, your only hope is to buy the manual from Japan, and if you are lucky enough to find it, it will be in japanese writing, and I don't even think they call them service manuals there. The worldwide equivalent is probably a GF-9696, but there are different suffix versions of that GF-9696 as well. Anyone that buys a japan only model should know that servicing them will potentially have these issues.

 

[BoomboxLover48]

Hi,



Superduper is the tech Guru here.
Like he said we don't have a manual for this unit. Actually, he told me to flex the board and check for any loose solder connections and that is how I figured it.

Oh my! IC issues? Good luck with getting the replacement IC! There must be a reason for it to malfunction. May be higher voltage to a 100V unit?
Our expert members here can help with the IC selection.

Now this is a good time to clean the long record bar switch which is a culprit for many problems. Clean the record bar squirting Deoxit Fader 5 and work it a minimum of 25 times. Also clean all the sliding switches.





~Royce

 

[Mota74V8]

Hi!

I found several IC 1185H2. But no 1185H (1).
I found a datasheet for the 1185H2, but nothing about the 1185H (1).
I found manuals too, but they were very expensive.
My current challenge is to figure out if the 1185H2 is just an update to its predecessor or is completely different.
I've already cleaned all the controls.
More news later :>)

Thanks,

Mota

 

[BoomboxLover48]

​

UPC1158H2 Product details

​

​ DESCRIPTION The μPC1158H2 is a silicon monolithic integrated circuit designed for high gain, low noise preamplifier with Automatic Level Control (ALC). As an advanced production process is used, the device has an excellent feature of very low pulsive noise characteristics. It is ideally suitable for use as a recording and playing amplifier in a cassette tape recorder.

UPC1158H2 pdf, UPC1158H2 Description, UPC1158H2 Datasheet, UPC1158H2 view ::: ALLDATASHEET :::

Contact DigiKey and ask them if they have IC 1185H1. They might be of help.

 

[Superduper]

I don’t see any obvious outward appearance of damage to that chip, are you sure it’s bad? On chips with burning smell, I’ve often seen holes in them. This is a preamp chip and only handles small currents, I wouldn’t expect burning damage. That being said, if it’s bad and only the (2) version is available, I would go ahead and change it, but probably get 2 so you can change the other channel to match in case there is slight difference in characteristics.