News:

Forum upgrade to SMF 2.1.2, still working on re-theming.

Main Menu
Welcome to Solid State Guitar Amp Forum | DIY Guitar Amplifiers. Please login or sign up.

May 17, 2022, 05:19:53 PM

Login with username, password and session length

Recent Posts

 

Hartke HA5000 tripping relay

Started by markorock37, December 05, 2021, 05:20:23 PM

Previous topic - Next topic

markorock37

Working on a Hartke HA5000. Had 3 blown power transistors and both drivers on right amp. Replaced those with exact part numbers and also replaced the six .47 ohm resistors. The amp works fine in mono mode and in bi-amp mode through the high output jacks. When plugged into the low output jacks the relay opens after 30 seconds or so and cuts the sound. I can't find any info or setting the amp (there is 2 trim pots on the board) just a schematic. Both channels have equal B+ voltage going to them. Anything else I should check?

Enzo

Sure.  Power up with no load.  Allow the few seconds so the speaker relay clicks on.  Now, is there any DC voltage sitting on the output?   Something is off on the low side power module.

Bias?  Maybe, is the heat sink getting hot in that 30 seconds?   I'd just turn the bias to the coldest setting and see if it stays awake.  If so, fine tune it later.

markorock37

Nothing is getting hot. But yes I measured high dc on the low side .195v. High side is at .053V but that side works and that seems alright.

Enzo

You said it has to run 30 seconds before it trips.  Does that offset voltage slowly grow?  or is it just 0.2v high from the start?

The TA7317 circuit could be acting up.  The chip itself is usually reliable,  but I often find the little electrolytics are not.  The amp is what, 15-20 years old?  Those age.  Let us explore that.

There is a tiny negative supply to pin 1, with a little 1uf/50v cap.  That supply is a reference for the chip.  Off pin 7 is a teensy 0.47uf/50v e-cap.  and to the right is another 1uf/50v.  Those are always suspect whenever I chase shut off issues in these amps.  And when I replace those, I go ahead and replace the 470uf/10v and the 100uf/25v too.  All those are clustered around the 73317 IC on the schematic.

markorock37

Sometimes it shuts off sooner. I was thinking the aged electrolytics may be causing the problem. I'll change those out and see what happens.

markorock37

Finally I had a chance to change all of the electrolytics on the offending amplifier board. That was it! The amp is working great now and sounds good too. Thanks Enzo for pointing me in the right direction. Your help is always appreciated.

Mark

joecool85

Quote from: markorock37 on December 23, 2021, 10:16:17 PM
Finally I had a chance to change all of the electrolytics on the offending amplifier board. That was it! The amp is working great now and sounds good too. Thanks Enzo for pointing me in the right direction. Your help is always appreciated.

Mark

Rock and roll!  Glad to hear it's working and good job with the repair!  :tu:
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com