Crate V50 help

[Cramer1]

I recently pulled a Crate V50 out of the garage of my recently deceased uncle. It was headed for the trash pile so I brought it home and plugged it in and it works!

The input Jack was loose so I pulled the back panel and tightened it up. While I was in there......... I noticed that R102, R103, R104, and D101 are scorched. They may look worse than they are due to the “goop” that crate appears to use to hold things in place.

My initial thoughts are that I should pull the power supply board and replace those components just to be safe. I have read that crappy power tubes may be the cause of this issue in these amps. I looked at the power tubes and they are labeled as “Ruby” tubes, does anyone know or have an opinion about these?

Again, the amp functions, just trying to catch any pending issues.

[Cramer1]

Pic of the affected components

[Cramer1]

Here’s a schematic

[vampwizzard]

not sure if its necessarily heat damage but id replace those components just to be safe. Tubes are tubes.. if they work they work. My memory tells me the crates ran hot.. nothing really to do about it.. may just be the design.

[Latole]

Crate V50 review;

http://mypartition.com/Articles/CrateV18Article/CrateV18Article.html

[Cramer1]

Thanks guys! Yeah I was unsure about tubes being the culprit. Those Particular components getting burnt seems to be a fairly common occurrence based on a little bit of googling. I will just replace them to be safe, I did see a reference to some finned resistors to help with heat dissipation, but no specifics.

Anyone one have any experience with these amps? Seems decent enough.

[PRR]

...Tubes are tubes.. if they work they work....

It's not tubes. He is pointing at the Switch-Mode Power Supply which connects to the wall-power, jiggles a Transistor at 30KHz, and makes 400VDC. Specifically the "catch" network which absorbs some parasitic flyback energy. If the SMPS is designed and built correctly, this won't run warm. I suspect the cost-cutters worked overtime on this one and it is doomed.

[Latole]

Thanks guys! Yeah I was unsure about tubes being the culprit. Those Particular components getting burnt seems to be a fairly common occurrence based on a little bit of googling. I will just replace them to be safe, I did see a reference to some finned resistors to help with heat dissipation, but no specifics.

Anyone one have any experience with these amps? Seems decent enough.

With schematic and amp in front of me it will be easy to find resistors values if we can't read color code on them.
Look a 2 watts resistors. Il'll replace them by 5 watts cement

[Cramer1]

Thanks guys! Yeah I was unsure about tubes being the culprit. Those Particular components getting burnt seems to be a fairly common occurrence based on a little bit of googling. I will just replace them to be safe, I did see a reference to some finned resistors to help with heat dissipation, but no specifics.

Anyone one have any experience with these amps? Seems decent enough.

With schematic and amp in front of me it will be easy to find resistors values if we can't read color code on them.
Look a 2 watts resistors. Il'll replace them by 5 watts cement

So you are suggesting replacing the resistors with something that will take a higher wattage? The schematic shows two 2 watts and a 1 watt.

[j_bruce]

With schematic and amp in front of me it will be easy to find resistors values if we can't read color code on them.
Look a 2 watts resistors. Il'll replace them by 5 watts cement

So you are suggesting replacing the resistors with something that will take a higher wattage? The schematic shows two 2 watts and a 1 watt.

I think he is.

I would use 4 watt resistors. It will cost $1 more for parts and no additional time.

[vampwizzard]

...Tubes are tubes.. if they work they work....

It's not tubes. He is pointing at the Switch-Mode Power Supply which connects to the wall-power, jiggles a Transistor at 30KHz, and makes 400VDC. Specifically the "catch" network which absorbs some parasitic flyback energy. If the SMPS is designed and built correctly, this won't run warm. I suspect the cost-cutters worked overtime on this one and it is doomed.

Agreed. Thats my point. the tubes weren't going to cause this. Even if they ran the bias hot like most crates do from the factory something else was at fault.

[Latole]

Thanks guys! Yeah I was unsure about tubes being the culprit. Those Particular components getting burnt seems to be a fairly common occurrence based on a little bit of googling. I will just replace them to be safe, I did see a reference to some finned resistors to help with heat dissipation, but no specifics.

Anyone one have any experience with these amps? Seems decent enough.

With schematic and amp in front of me it will be easy to find resistors values if we can't read color code on them.
Look a 2 watts resistors. Il'll replace them by 5 watts cement

So you are suggesting replacing the resistors with something that will take a higher wattage? The schematic shows two 2 watts and a 1 watt.

In my town 5 watts resistors are alway on the shelf, not 2 or 1 watts.

I have all 1/2 and 5 watts in any value in stock at home.

[dude]

If the amp plays those power rail resistors are not blown, probably under wattage. You can replace them without taking the bd out. Scrape the goop off, cut the body out leaving the legs as long as you can, solder the new at least 3 watt R’s to the legs. If there 2 watts on the schematic, use 3 watts, a five watt cement R will be too big. They sell 5 watts that are smaller than cement but 3 should be fine.

[Latole]

For a familiar with circuits and soldering, it is not very difficult to install 5 watts.

The best is doing what you can ; order 2 watts if you can't work with 5 watts resistor

[Cramer1]

Based on the schematic I show 1 22 ohm and 2 33k ohm resistors? Also, the goop is baked on so cleaning the components may do more damage than good.

[Latole]

You talk about those resistors  ?

I don't know, I have to see wiring on circuit

[Cramer1]

You talk about those resistors  ?

I don't know, I have to see wiring on circuit

Yes those

[Latole]

You have to follow wiring on the circuit to be sure.  Or you do ?

[Cramer1]

You have to follow wiring on the circuit to be sure.  Or you do ?

I’m not sure I follow?

[Latole]

You have to make sure that the resistors you are going to change on the printed circuit are the ones you are talking about in the diagram.

You will have to confirm that these resistors to replace are connected correctly as the diagram shows it.
They should not be confused with others and put other values.

This is exactly what I said that with the photo alone, I cannot affirm that it is the same resistors.

[Cramer1]

You have to make sure that the resistors you are going to change on the printed circuit are the ones you are talking about in the diagram.

You will have to confirm that these resistors to replace are connected correctly as the diagram shows it.
They should not be confused with others and put other values.

This is exactly what I said that with the photo alone, I cannot affirm that it is the same resistors.

Oh ok. Yes I still need to pull
The board to verify and pull measurements but the labels stamped
on the board point to those components.

[Cramer1]

Ended up putting in 5W resistors and a fresh diode. Also got most of that baked on goop off when I pulled the old components. We’ll see what happens! Thanks for all the advice and help guys!

[Latole]

Ended up putting in 5W resistors and a fresh diode. Also got most of that baked on goop off when I pulled the old components. We’ll see what happens! Thanks for all the advice and help guys!

 

[Cramer1]

Played through it today and didn’t let the magic smoke out so I guess that’s good. The settings are interesting. I can get some serious reverb and a wet tone at lower volume/gain, but to get good drive it’s pretty loud lol.