garydean
Member
Does anyone know who makes an output transformer for a 1990 .50 Caliber +, 1x12 combo?
any leads would be greatly appreciated.
Gary
any leads would be greatly appreciated.
Gary
Output Transformer for a .50 caliber + 1990
- Thread starter garydean
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garydean
Member
Thanks for the lead Stomper. I just shot them an email. They do look pricey.
Gary
Gary
disassembled
Well-known member
Is your original bad? If so are you positive or just guessing?
Greg
Greg
garydean
Member
The amp came in for repair with the OT dangling from one tab. I built a bracket around it and secured it to the chassis. The signal is very weak, hardly audible with the volume knobs turned up to 10. At one point it did suddenly kick in with plenty of static to boot. The 60 cycle hum was too obvious as well. Then the signal stopped and the symptoms were back. I swapped out all the tubes and applied a 1000hz signal to the input and traced it to the output. All seemed fine till I got to the lug on the 8 or 4 ohm output jack, where I lost the signal. I disconnected the leads from the dummy load end and the signal appeared perfectly. Am I missing something here? All voltages were in spec. and I cleaned the board and all contacts.
Thanks,
Gary
Thanks,
Gary
What's the bolt pattern dimensions? Seems like lots of Mesas, especially the older ones, share transformer envelope dimensions with Fenders. Might be that a Bassman-size OT would bolt in, and would be a LOT cheaper than Mercury.
If you need lots of taps, the Prosonic OT has 4/8/16 taps and is Bassman sized.
If you need lots of taps, the Prosonic OT has 4/8/16 taps and is Bassman sized.
garydean
Member
Has 2 mounting tabs total.
4/8 ohm.
hole spacing 3 1/8
2 1/2 x 2 3/4 wide , 2 7/8" tall
4/8 ohm.
hole spacing 3 1/8
2 1/2 x 2 3/4 wide , 2 7/8" tall
garydean
Member
WoW that sure looks like a perfect match for what I have. Thanks for the lead, and the price is on the money.
Gary
Gary
garydean
Member
The curious side of me wants to remove the bad OT and disassemble it and see what's up in there. I've repaired a few analog meters in the past because I needed to know if I could. I'm figuring if a tab is cracked or broken I may be able to do something with it. An open winding would be a different story. Just because I did get a signal for a brief moment leads me to believe it may be salvageable.
Gary
Gary
scottcrud
Well-known member
Ever noticed how small the trannies are on the .50 cal+? I don't believe they ever put out 50 watts at all, maybe 30-35 tops. I put mine up against a Trayner 50 watt reverbmaster and a 50 watt Marshall and the Boogie was buried by both of them.
disassembled
Well-known member
Definitely sounds repairable.
So what you're saying is after you scoped it out and removed the load resistor it worked fine?
Let us know what the hell is going on if you find out.
Grge
So what you're saying is after you scoped it out and removed the load resistor it worked fine?
Let us know what the hell is going on if you find out.
Grge
garydean
Member
I'm still in the position of weather or not the OT is bad or not. I did notice a slight discoloration on the board around R261. I guess I just need to bite the bullet and order in a new OT. I've had 4 repairs come through and still this Boogie sits waiting to be fixed. Can someone explain to me why I loose the signal on this amp when I'm connect to the dummy load? Weather or not I plug into 4ohm or 8ohm, the signal goes flat. I'm probing at the jack lug and when I pull out the plug to the dummy load the signal comes back. If the OT was bad I wouldn't get such a great signal at all.....right?
aaahhhh!!
aaahhhh!!
I bought a DC-2 years ago that had a bad OT. It would play fine at lower volumes and sounded incredible. It sounded much like you are describing at higher volumes.
It had a burned, but not quite open, wire in one of the coils. There was 1/4" size burn in the paper that surrounded the coils.
I could have fixed it, but chose to use a Mojotone (Heyboer) replacement instead. It fixed the problem immediately and sounded better than ever.
With the price of the Allens being lower than Mercury (both are great transformers by the way), I would say just get it and see if it fixes your problem.
It had a burned, but not quite open, wire in one of the coils. There was 1/4" size burn in the paper that surrounded the coils.
I could have fixed it, but chose to use a Mojotone (Heyboer) replacement instead. It fixed the problem immediately and sounded better than ever.
With the price of the Allens being lower than Mercury (both are great transformers by the way), I would say just get it and see if it fixes your problem.
garydean
Member
Thanks for the push Monsta. It's one of those...should I, or shouldn't I situations. I'm not gonna fix it till I eliminate the OT as a potential problem. the other thing is the electrolytic caps are from 1990 (original) and should be replaced as well. This amp needs plenty of work.
thanks again,
thanks again,
You might try a cap job 1st to see if that helps. I always replace the Bias cap too when replacing electrolytics.
I know what you mean about having to eliminate things. When I first started working on amps, I always pointed to the OT, and was always wrong. The DC-2 was the 1st & only OT that I've ever had go bad.
I have bought a few amps that simply did not have them when they arrived though. :x
I know what you mean about having to eliminate things. When I first started working on amps, I always pointed to the OT, and was always wrong. The DC-2 was the 1st & only OT that I've ever had go bad.
I have bought a few amps that simply did not have them when they arrived though. :x
garydean
Member
I wouldn't have even considered the OT but it came to me dangling by the wires. Do you think I need to remove the board or can I replace the caps from the top? I'm not used to seeing this kind of board where there is a bead of solder on both sides.
thanks,
thanks,
I've never looked inside a .50 cal, but I had a Studio 22+ for a while, and all of the components were on the bottom of the board. Made it a huge pain to get to them.
I heated them up and pryed them out with a dental pick. Then, I replaced them on the top of the board for easier access.
Every Mesa that I've seen has the double plated pads. I really like them.
All you have to do is heat the pad up and pull on the lead a tiny bit with a dental pick. Then suck the solder out, it's much easier to do if the part is removed 1st.
The hole that the lead goes through is plated also, so it should heat up the entire solder connection. Be careful on more delicate parts like LDR's though, because it is easy to overheat them.
I heated them up and pryed them out with a dental pick. Then, I replaced them on the top of the board for easier access.
Every Mesa that I've seen has the double plated pads. I really like them.
All you have to do is heat the pad up and pull on the lead a tiny bit with a dental pick. Then suck the solder out, it's much easier to do if the part is removed 1st.
The hole that the lead goes through is plated also, so it should heat up the entire solder connection. Be careful on more delicate parts like LDR's though, because it is easy to overheat them.
garydean
Member
Great advice... thank you.
Gary
Gary
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