Tascam 38 No sound in Sync Mode!

[vhbram]

All fuses are working. Everything else is soldered fine.

Is there a way to check if the IC's are not broken? I put 2 SN7400N's in place of the exploded ones. Is there maybe a difference in the old IC's and the new ones? Or can I just use SN7400N as a part replacement?

Thanks

 

[Gcalo]

If the SN7400N's are what is called for then you should be OK there. If not you have a problem. Make sure you have the Xref correct.

Give me the Tascam IC# and I will check a Xref table.

I would also go through and check every transistor on the control board. I would start with the large rail mounted unit, and then move on from there to everyone.

You are probably not getting a signal to the IC's due to gating through some switching transistors.

 

[vhbram]

I've already checked all the transistors. They seem fine, they all measure around 700. I'll check them again.

Tascam IC: M74LS00P (614002)
and the one SN7474N: M74LS74AP (5170E2)

The new I swichted with the exploded ones:
SN7400N (09E76VK)

Thanks again!

 

[Gcalo]

I do not know what the "700" measurement is you ststed. That makes no sense to me. Either there is conductivity across the pins or there is not.

I think you need to check all the transistors again.

I'll look at the Xref for those IC's

 

[Gcalo]

Tascam IC: M74LS00P (614002) - I do not see this one in there. I see a SN7400N
Where did you get the "P" designation?

 

[vhbram]

I have a digital multimeter that can measure diodes. I've checked every transistor and they all measure around 567 when I measure PN and zero when I measure NP. I suppose that should be right and the transistors should be working?

Concerning the my SN7400N IC, I've found one on ebay:
http://www.benl.ebay.be/itm/M74LS00P-Ma ... 56513a84f4

What do you mean with the "P" designation?

 

[Gcalo]

This is the one you stated- Tascam IC: M74LS00P (614002)

Where did the "P" designation come from?

 

[vhbram]

I don't now where the designation comes from, the original Tascam IC code is stated like that. I've just read it from the IC itself.

I've just found a control PCB on ebay:
http://www.ebay.co.uk/itm/Tascam-34B-Re ... 0948852173

It's from a Tascam 34B, but it looks exactly the same. Do you think it could be switchable with mine?

 

[Gcalo]

Definitely No! They may be similar but not the same.

Don't waste your $.

You need a 38 series control board from a unit that is well below unit S/N 4000000 series.