Crate TD70 fades out

[sam0812]

HI Ive got an old CRATE TD 70, tube preamp SS power amp.Everything works fine but after an hour or so of playing [either loud or quiet] it fades out to nothing over a period of about 5 seconds, not instantly.If I plug a lead into the line out socket it crackles,pops etc comes back to life, but only for 5 or 10 minutes then fades out again. Ive replaced the 12ax7 preamp tube but as far as ive got.Any Ideas THANKS SCOTT

[Enzo]

If you have a jack marked power amp in or effects return or even insert, clean its inner contacts. I would suspect it is failing.

[sam0812]

Thanks enzo, I pulled the chassis out and wd40'd all the jacks[which by the way are the wierdest jacks ive seen,enclosed complicated looking]Amp went for 3 hours straight ,no problem Thanks again SCOTT

[bluesman123]

I had the same problem

Hi there I had the same problem with my TD70 and found it to be the voltage rail zener diodes which were failing the longer the amp ran they are IN5353B type fault was the same fading out low volume then back in for short period loud as hell you'll find them top left on the board I'll attach schematic and board layout you'll probably find evidence of overheating on the P.C.B. around them.

[Gtr_tech]

Oh my GAWD....do we need to go thru THIS again?

FFS, DO NOT USE WD40 for *anything* involving electronics. It is NOT electronic grade contact cleaner, its a cheap lubricant. And it turns into a goop that attracts dust/dirt.

What you need to do now.....get some cleaner/degreaser that won't attack plastic. Naptha (wick lighter fluid <Zippo type>) works pretty well. Flush out the jack several times while working the contacts to get that shit outta there.

This stuff is cheap and works well to clean jacks and pots as well as other connectors:
GC Electronics - 19-638 - Chemicals - Chemicals & Adhesives - Allied Electronics

Now....what you shoulda used the first time:
Amazon.com: GC Electronics DE-OX-ID Contact Cleaner (4 oz.) : 19-1906: Electronics

Thats the stuff that will actually deoxidize contacts.


NO WD40!!!!!

[GainFreak]

By the way thanks for the schematic. I had no luck finding it some time ago.

[Enzo]

Relax, that WD40 comment came from a 2008 post.

[Gtr_tech]

Heh....didn't even look at the date. At any rate....people should know that WD40 has no business being used as a contact cleaner. I tend to get fired up when I hear of this happening....

[Enzo]

Well, no wonder... WD40 is flammable. (No drummer pun intended) Not the stuff to have around if it gets you fired up.

[sam0812]

Ok ... It was me....Im Sorry I used WD40 on my amp...I Didnt know

I Got the amp fixed ..[one of the best little amps Ive ever had] and I sold it. The Guy who fixed it said it was a transformer problem.[I think maybe bullshit] Thanks for the replies and info regards Scott

[anubismaximus]

good day

can you send the file to my email maxivanegas.yupi@gmail.com does not let me download attachments

thanks

[g1]

Here is the schematic: https://music-electronics-forum.com/...5&d=1560974103

[anubismaximus]

Here is the schematic: https://music-electronics-forum.com/...5&d=1560974103

someone has the design of the circuit board as it comes in the service manual,

[DrGonz78]

If the manufacturer doesn't supply a board layout then I don't think you will find it.
https://supportloudtech.netx.net/fil...nal/attachment

[nosaj]

someone has the design of the circuit board as it comes in the service manual,

Why do you need the layout? by the schematic it doesn;t look to be a very complex amp. Are you having problems finding something?
nosaj