Sony TA-E88 Fet Replacement Problem

[tvi]

It was a HP part: 1855-0434 = IT500

Sphere research is where I found the Cross ref data, they use to list the part too, but I helped a guy on the Asylum with a similar problem awhile ago and now the listings gone. Might be worth an email though.

Click here for the data sheet, I cleaned them up a bit.

militarycomponents.com site say they have 2 IT500s in stock; 19 IT501s, 6x IT502s and lots of IT505s.

Best of luck.

Regards
James

Wouldn't mind a copy of the Shematics if you have them.

 

[zedrider]

James

Thankyou very much for all that information i have sent out searches and emails and will see if any of them produce a result, the guy at the military electrinics place i have spoken to on line (http://finance.groups.yahoo.com/group/buys_sells_consignments/) and he tells me that he is waiting for his supplier to confirm that he has the two shown as being in stock.

I will scan in the schemetic for this pre-amp, i will have to do it in sections as i ony have a A4 size scanner, do you want me to email them to you or put a link on here

Thanks
Gary

 

[zedrider]

It was a HP part: 1855-0434 = IT500

Sphere research is where I found the Cross ref data, they use to list the part too, but I helped a guy on the Asylum with a similar problem awhile ago and now the listings gone. Might be worth an email though.

Click here for the data sheet, I cleaned them up a bit.

militarycomponents.com site say they have 2 IT500s in stock; 19 IT501s, 6x IT502s and lots of IT505s.

Best of luck.

Regards
James

Wouldn't mind a copy of the Shematics if you have them.

Hello james
I have scanned in the schemetic diagram each one is about 2 meg so if you are not on broadband they may take a while to come through, it was the only way i could preserve the detail on them

http://www.btinternet.com/~swlthr/ebay/pcb1.jpg

http://www.btinternet.com/~swlthr/ebay/pcb2.jpg

http://www.btinternet.com/~swlthr/ebay/pcb3.jpg

I hope they are of use to you

Gary

 

[tvi]

I will scan in the schemetic for this pre-amp, i will have to do it in sections as i ony have a A4 size scanner, do you want me to email them to you or put a link on here

Either way suits me, but a link would let everyone interested have a look.

Regards
James
tvi@optusnet.com.au

 

[tvi]

Should have reloaded the thread/page before post.

Thanks
James

 

[zedrider]

Hello james

and anyone who is looking at the pix, you will need to switch off the "enable automatic image resizing" option in your browser to get these scans at full size. If you want to save them and view them properly


Gary

 

[wrenchone]

If you have no luck getting the original replacement part, I would try matching a pair of 2SK170s (MCM has them). You can match for Vgs using a current source set to 1/2 the idle current of the differential stage (a 2-transistor current source works well), and a couple of 9V batteries to bias everything up. "Air" construction will be ok for the current source, since this is more or less a one-time deal. I have a dedicated jig for this, but I match JFETs all the time...You would probably need 20 pieces of 2SK170 to find a decent match. The pair you select would constitute the bottom half of the differential pair. The cascode FETs on top need to be either from a higher IDSS group or from a different family, so that some voltage is impressed on the bottom pair of FETs. I would use PN4393s to make sure there is some voltage, but that's because I have both FET types lying about. Exact matching is not critical on the top cascode FETs. I can understand why the original FETs are out of production, as there must be four separate die in that little package, two matched....

 

[zedrider]

Hello

Thanks very much for your advice on replacement fets to try in place of the IT500s.

I have given up trying to get IT500s from places that claim to have them.

I have now removed two IT503's from the headphone amps (one in each channel), i have put the IT500 from the good channel (right) into the left channel buffer amp and can use the trimmer pot to obtain "O" volts DC on the output so that channel is working fine now, i then put one of the IT503's in the right channel and tried it, this one i could not get rid of all the DC so i tried the other IT503 and this one i can trim out the DC.......christ these fets are ******s!.....i do not know what sort of tolerencing they have on them.......so after all this fiddling about with other fets patched together etc....it is all working now.
The headphones socket i have just connected to the Line out and this works fine, why Sony went to all the trouble of building a headphone amp i do not know. But the fets in it have been useful.

But your comments about trying about 20 pairs to get a well matched pair makes absolute sense.......the originals have 4 fets and 4 diodes in them.......i wonder how many they must rejected when making them.

So thankyou to everyone who has replied with advise and tips on this thread.

Gary

 

[mlloyd1]

schematic for sony ta-e88?

a friend is planning to send me a sony ta-e88 preamp he wants fixed.
before i get it, i'm looking for a schematic. i'm really hoping the problem does not involve replacing those funky cascode jfets.


anyways ...

a search brought me here but all the links appear no longer valid.
any pointers to a schematic are much appreciated.


thx,
mlloyd1

 

[tvi]

I have the Schematic as a pdf, 5.5meg, will need a email address.

Regards
James

 

[tiefbassuebertr]

In this case I have started this thread:
http://www.diyaudio.com/forums/soli...kin-2sj28-2sj18-2sk60-2sj26-2sk76-2sk180.html

 

[jackx]

Sony TA-E88

I have the Schematic as a pdf, 5.5meg, will need a email address.

Regards
James

Hi James,
I have a Sony TA-E88 on the way and I plan to recap it as suggested when it arrives. Would really appreciate it if you could share with me a copy of the schematic!

Regards.
Jack
hjackxiao@hotmail.com