kinser Posted June 10, 2022 Report Posted June 10, 2022 Recently had a boost pump regulator go out on me and just replaced the blown diode and transistor to get it back up and going. I'd like to sanity check the voltages coming out of the regulator though... what is considered normal from an output perspective? It is all adjustable via a trimmer potentiometer, just wondering where to start. Quote
carusoam Posted June 11, 2022 Report Posted June 11, 2022 Kinser, This is where it is good to mention your skills as an electrical technician / A&P… etc… Plenty of people that want to help you… They just need to know you are not a pilot fixing his own plane… Let us know how it goes… These things fail every couple of decades… eliminating the Lo fuel output. let’s invite @M20Doc to the conversation… (boost pump regulator question m20r) Best regards, -a- Quote
N201MKTurbo Posted June 11, 2022 Report Posted June 11, 2022 I would look at the boost pump and see what voltage it is rated at and adjust the regulator accordingly. 1 Quote
N201MKTurbo Posted June 11, 2022 Report Posted June 11, 2022 Just looking at the circuit, it doesn't look like a voltage regulator, it looks like some kind of timer. If that's the case, it should be 28 volts coming out. I would replace the relay. Quote
N201MKTurbo Posted June 11, 2022 Report Posted June 11, 2022 That all being said, that's a pretty old school single sided hand routed PCB for 2000. They must have had the old guy do it... Quote
larryb Posted June 11, 2022 Report Posted June 11, 2022 The same guy must have designed the other little boxes like the LED bar graph indicators and the flap relay board. All have the same look and feel. My understanding is that the regulator is for low-boost. In high boost the pump gets full 28V and in low-boost the pump gets a lower regulated voltage. So the question is, what is the proper voltage for low boost? Somebody would probably have to measure it. What is odd about the picture is I don't see any typical larger power handling transistors with heat sinks that you would typically use in this application. Larry Quote
carusoam Posted June 11, 2022 Report Posted June 11, 2022 The start-up transition on Lo must be a killer… If the pump doesn’t start right away… there is probably a ton of heat generated instead. PP thoughts only… Best regards, -a- Quote
Guest Posted June 11, 2022 Report Posted June 11, 2022 15 hours ago, kinser said: Recently had a boost pump regulator go out on me and just replaced the blown diode and transistor to get it back up and going. I'd like to sanity check the voltages coming out of the regulator though... what is considered normal from an output perspective? It is all adjustable via a trimmer potentiometer, just wondering where to start. The procedure is in the engine fuel set up section of the manual. You adjust the pump to set a specific output fuel pressure. Clarence Quote
kinser Posted June 11, 2022 Author Report Posted June 11, 2022 10 hours ago, carusoam said: Kinser, This is where it is good to mention your skills as an electrical technician / A&P… etc… Plenty of people that want to help you… They just need to know you are not a pilot fixing his own plane… Let us know how it goes… These things fail every couple of decades… eliminating the Lo fuel output. let’s invite @M20Doc to the conversation… (boost pump regulator question m20r) Best regards, -a- Oh don't worry, there is a rebuilt unit from an approved shop on the way for the actual aircraft. I just couldn't see a board that looks this straightforward and not try to resolve it. 10 hours ago, N201MKTurbo said: I would look at the boost pump and see what voltage it is rated at and adjust the regulator accordingly. The pump itself is rated at 28v, which it gets when the high boost rocker switch is activated. This regulator is just used for low boost, hence the need for the lower voltage to achieve a lower output. 9 hours ago, N201MKTurbo said: Just looking at the circuit, it doesn't look like a voltage regulator, it looks like some kind of timer. If that's the case, it should be 28 volts coming out. I would replace the relay. Oh it's definitely a regulator. The transistors are on the backside. 9 hours ago, N201MKTurbo said: That all being said, that's a pretty old school single sided hand routed PCB for 2000. They must have had the old guy do it... It kind of looks like what I would make for science projects in high school. And not just the board itself, but also the box containing it. It looks just like what radio shack used to sell as "project boxes". 8 hours ago, larryb said: The same guy must have designed the other little boxes like the LED bar graph indicators and the flap relay board. All have the same look and feel. My understanding is that the regulator is for low-boost. In high boost the pump gets full 28V and in low-boost the pump gets a lower regulated voltage. So the question is, what is the proper voltage for low boost? Somebody would probably have to measure it. What is odd about the picture is I don't see any typical larger power handling transistors with heat sinks that you would typically use in this application. Larry You hit the nail on the head with regard to the low vs high boost aspect. As for the transistors, they're mounted on the backside of the board and use the metal case itself for heat dissipation. That design does make things cumbersome though, because the transistor cannot ground to the case, despite mounting to it. So they couldn't use normal thermal paste for the backside of the transistor and instead has to use fiberglass based thermal pads and plastic screw insulation shims and mounts. It seems... sketchy. 58 minutes ago, M20Doc said: The procedure is in the engine fuel set up section of the manual. You adjust the pump to set a specific output fuel pressure. Clarence Ah, so no set voltage, just whatever is necessary to achieve to desired pressure. Thank you! 2 Quote
Dominik_B Posted August 21, 2023 Report Posted August 21, 2023 Hi kinser, i got a similar problem... Can you tell me what type of transistor you used as a replacement? thanks Dominik Quote
Fly Boomer Posted August 21, 2023 Report Posted August 21, 2023 58 minutes ago, Dominik_B said: Hi kinser, i got a similar problem... Can you tell me what type of transistor you used as a replacement? thanks Dominik Welcome to MooneySpace! It's been almost six months since kinser was here, so he may have moved on. That said, this forum doesn't work like email -- if you want to notify another poster that you have responded, you need to quote part of their post by selecting some of their text and then clicking the "Quote" pop-up, OR by inserting their name with an "at sign" followed immediately (no space) with their screen name. This use of the "at sign" will display a pop-up box with suggested names you can select from. Good luck. Quote
kinser Posted August 21, 2023 Author Report Posted August 21, 2023 2 hours ago, Dominik_B said: Hi kinser, i got a similar problem... Can you tell me what type of transistor you used as a replacement? thanks Dominik Hey @Dominik_B -- there are two components there, the rectifier (2 legs) and the bipolar transistor (3 legs). I'll link to the ones I used below. And just in case someone is reading this years in the future and the reseller has removed their product pages, the rectifier is MUR1540G and the transistor is 2N6668 PBFREE. https://www.mouser.com/ProductDetail/onsemi/mur1540g/?qs=Gev%2bmEvV0iZq6LchZ03NqA%3D%3D&countrycode=US¤cycode=USD https://www.mouser.com/ProductDetail/Central-Semiconductor/2N6668-PBFREE?qs=l7cgNqFNU1ijRYXR1DLWNQ%3D%3D&countrycode=US¤cycode=USD 1 Quote
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