GK 250ML Blowing Fuse

[g1]

That's better.
No swords. And no pistols either, whatever that's doing there.

[sweatyk]

If I had a working channel I would leave it alone...it works. Transistors don't "wear out", they just fail. They might run for thirty years.

TIP35C/36C? Sure, why not? They are beefier versions of the other.

I've had to take a few weeks off from this and still have not ordered the parts. Before I do I wanted to ask being I don't have a true understanding when comparing transistors like this but I noticed that the C - B and C - E voltage ratings on the datasheet for the TIP34C (original part) are listed as 140V and on the TIP36C (possible replacement) lists at 100V. Is that going to make a huge difference if any at all?

[The Dude]

The actual rail voltage in the amp is only +&-45V, so no- it won't matter.

[sweatyk]

The actual rail voltage in the amp is only +&-45V, so no- it won't matter.

Thanks!

[Enzo]

Imagine you weigh 200 pounds and you need a stepladder. The one you used to use before it was stolen was rated for 250 pounds. Seems pretty safe. Now a suggested new one has a 300 pound rating. Will that be a problem?

[sweatyk]

Imagine you weigh 200 pounds and you need a stepladder. The one you used to use before it was stolen was rated for 250 pounds. Seems pretty safe. Now a suggested new one has a 300 pound rating. Will that be a problem?

I get it. Makes perfect sense. However to use the same analogy I would be going from a 300 pound rating down to a 250 pound rating but still works for the application.....correct?

[Enzo]

A part either has sufficient specs or it does not.

[g1]

I noticed that the C - B and C - E voltage ratings on the datasheet for the TIP34C (original part) are listed as 140V and on the TIP36C (possible replacement) lists at 100V. Is that going to make a huge difference if any at all?

You are mixing up C-B and C-E voltage ratings. If both parts are 'C' suffix, the voltage ratings are the same (140V C-B, 100V C-E). Current and power dissipation are also both higher for 36 compared to 34 (25A vs 10, 125W vs 80). So TIP36 is superior part when both have same suffix.

I get it. Makes perfect sense. However to use the same analogy I would be going from a 300 pound rating down to a 250 pound rating but still works for the application.....correct?

Not really, see above.

[sweatyk]

Finally got some parts in for this. I replaced those that were bad and a couple of electrolytic caps in the power supply section while I was at it. I've highlighted on the schematic what has been replaced. Just powered it up using my dim bulb rig. So far it's a success. Before the bulb would light up like Broadway. I have very little spare time right now to go much further but wanted to share where I am with it at the moment. I will check voltages next to see where it is at before plugging my guitar in.

[sweatyk]

IT LIVES!!!!.....IT LIVE I TELL YOU!

I'm a happy camper today. Over a decade ago it was in a local shop for a humming issue. Unfortunately it was returned to me not working at all. So I held on to it until recently when I decided to dig into it. I'm glad I did. The last time it worked my 15 year old son was playing thru it......he's now 32

What a welcomed sound hearing it after all of these years. Just got thru playing it hooked to the current limiter just to make sure everything would be ok. Next I will need to replace the surrounds on the speakers to get it finished. Once I'm done with this one I have one more to repair but it only has one speaker in it. Any suggestions on where to get decent replacements for these? Has anyone found the perfect speakers for it? Also I'm debating on going ahead and replacing the 2 filter caps while I have it apart.....comments?

I want to thank you all for your input, comments, and advice......You guys rock!!!!

[Enzo]

The perfect speaker? Oh come on... That is right in there with the perfect woman or the perfect song.

[sweatyk]

The perfect speaker? Oh come on... That is right in there with the perfect woman or the perfect song.

Yeah Enzo looking back at that comment.......silly.

Let me trade that word out for the word suitable......If I had to buy speakers would like to know what would pair well with them..........to bring out their best quality as limited as it is.


Does that seem more appropriate......lol

[sweatyk]

It has been a slow process but so far I have managed to get the amp functioning, replace the surround edges on the speakers, and now it works however it has a chirping noise. This was with no input source, all controls turned to zero and no effects engaged. It sounds like a small bird like a squeaky wheel. I'll try to get a recording of it posted here.

[sweatyk]

[g1]

That has pretty stable timing. I'd say it's either related to the chorus, or some kind of outside electronic noise getting picked up.