Repairing my HB-F1XD

Rookie (20)

07-12-2018, 01:17

Hi folks. My friend is repairing my Sony HB-F1XD and he asked me to find him the following information:

"Found 2 issues with your msx. Seems at least one capacitor on the HIC1 has popped and taken out a transistor marked F4. I believe it's a BJT BC857 but so far cannot verify. Any chance the forums you're in can verify the transistor type? I've checked the (Japanese) service manual myself but the diagrams aren't that clear"

My electronics knowledge is zero, can anyone here answer? I can pass along any followup questions to him if need be...

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By RetroTechie

Paragon (1563)

07-12-2018, 02:59

You mean the one marked Q4, type F...something, that serves to mute the output sound?

Judging from how that's used, probably any common NPN transistor like a BC546 should do. Or whatever surface mount equivalent you can find. Just make sure the correct transistor terminals (emitter, base, collector) are connected to the correct points in the circuit (read: same way original transistor was connected). So if that Q4 was a surface mount part, would be useful to find replacement with same pinout.

By meits

Scribe (6534)

07-12-2018, 03:04

All smd capacitors on the hic must be replaced. If you're unlucky, the hic has to be cleaned and/or fixed as well.
Here's an old service manual.
There are some experienced "Sony hic computer fixing users" here who can help you further.

hic, notorious suicide board :(

By conceitedjerk

Rookie (20)

07-12-2018, 04:19

Thank you, I'll pass this info along to my friend, may have further questions.

By Pac

Scribe (6971)

07-12-2018, 12:14

More information here. And don't forget to check this great tutorial about its brother :) , I'm sure it will help.

By conceitedjerk

Rookie (20)

07-12-2018, 13:31

PERFECT! I'll forward these links to him, thank you!

By conceitedjerk

Rookie (20)

10-12-2018, 04:45

My friend just texted me a few minutes ago saying my MSX2 is fixed and seems to work fine. Thank you for your help, can't wait to have it back!

By meits

Scribe (6534)

10-12-2018, 11:25

That is so nice to read. Have joy with it.

By mals

Supporter (2)

11-12-2018, 07:53

Thanks to everyone for the help.

Now to return somethings to the community.

The damaged part was physically marked F4, and was listed on the schematic as Q1 "2SA1037" (an smd part).
The closest PNP part I had, was a Through Hole part 2N2907.
Watching the datasheets, you will have to twist and re-aligning the legs to match the original 2SA1037.

The following photo shows the new part highlighted in red

This second one has the Cap values listed and the location of Q1 written in red.

https://ibb.co/MgKG4bv