LPE 200 Power Issues

[VE3RADIO]

So I have a loaded LPE 200 with AEGIS, Provoice etc but I have one problem, there is no power! I read the service manual, and it suggested it would be bad contacts, a bad battery or a dead fuse. I have confirmed that the contacts are fine as is the battery.. but I cant find the fuse anywhere! Does anyone know where the fuse is located on one of these LPE 200? Any suggestions or am I out of luck? I paid almost nothing for the radio and the house is in MINT condition as is the battery and charger, so I am already on top.. but it would be amazing to get it working!

 

[mitaux8030]

Its not going to be the fuse. The fuse also protects the receiver, IF, synth and logic sections of the radio and they're obviously working fine.

There could be a problem where power output may have been inhibited in software (either through deliberate settings in Programmer, or perhaps corruption of the tracking data). These should be easy to find with a bit of digging.

Or it could be a hardware problem, such as the directional coupler or antenna switch, or associated power control loop (the LPE has an incredibly fast PCL by the way). It could be the PA amps or preceeding buffers could be faulty. Perhaps the PA power control voltages, or the TX BPF tuning voltages from Attie are faulty. Or perhaps the I&Q mod from Jacqui is faulty.

What is the current draw on TX? If its about 1.5 ampere, you're in the ballpark and that would indicate the PA is doing its thing, and everything ahead of it.
Do you get any transmitted RF, even just leakage? Check on a service monitor or similar, holding the LPE close to, but not right at, the monitor antenna. If you're hearing something (with correct I&Q modulation) then you can eliminate Jacqui as being faulty.
Its all a process of elimination first, then go looking for specific problems in the areas you've narrowed it down to.

 

[Thunderknight]

I think we need a clarification from the OP. Do you mean no power as in it will not turn on, or no power as in no RF (transmit) power?

I read your post to mean the whole unit will not power on (where as mitaux8030 read it to mean no RF power).

 

[VE3RADIO]

I think we need a clarification from the OP. Do you mean no power as in it will not turn on, or no power as in no RF (transmit) power?

I read your post to mean the whole unit will not power on (where as mitaux8030 read it to mean no RF power).

You are correct, no power at all, the unit is a brick. If it powered up I could use it as a scanner at least Any suggestions? Can the fuse be purchased at an electronics store etc etc?

 

[mitaux8030]

OK well the fuse F190 is located on the 'front' side of the main board, next to the B+ pin of the battery contact. Its a surface mount component that lays 'horizontally'. After that, diode V190 (which protects against reverse polarity) is also nearby, laying horizontally, in line with and at the end of F190. Check that its not gone short circuit.
N902 is a switch mode 5 volt regulator that powers the digital circuits. It'd be good to check for correct voltage input and output here too. Its a 16 pin surface mount device, down in the bottom left corner of the 'front' side of the main board... its a TL75LP48Q. Input pins 8, 9 & 10 from B+, and output pins 14 & 15. TP902 is a convenient point to monitor this output. Also, the device needs to be 'enabled' on pin 6, monitor this at TP900.

See how you go with that lot.

 

[VE3RADIO]

OK well the fuse F190 is located on the 'front' side of the main board, next to the B+ pin of the battery contact. Its a surface mount component that lays 'horizontally'. After that, diode V190 (which protects against reverse polarity) is also nearby, laying horizontally, in line with and at the end of F190. Check that its not gone short circuit.
N902 is a switch mode 5 volt regulator that powers the digital circuits. It'd be good to check for correct voltage input and output here too. Its a 16 pin surface mount device, down in the bottom left corner of the 'front' side of the main board... its a TL75LP48Q. Input pins 8, 9 & 10 from B+, and output pins 14 & 15. TP902 is a convenient point to monitor this output. Also, the device needs to be 'enabled' on pin 6, monitor this at TP900.

See how you go with that lot.

So yeah, I took it apart and found F190 (its not a pop-off job like I was hoping for) I also do not know how to test it.. Do you guys know any places that could fix this radio for me fairly cheap?

Also that add on board that is below on the front side that snaps on and off.. would that be where the options are stored?

 

[mitaux8030]

Hmm. Testing a fuse, even a SMD fuse, is "electronics 101" stuff, really easy. If you're not sure how to do this, I'm not sure how successful your attempts to repair delicate and quite small SMD electronic circuitry would be. It might be best to seek a repair shop for this as you've indicated.
I'm not near you, so probably won't be of any use suggesting any places to seek repairs from in your area. If you don't get any where, let me know... might be able to assist in some way.

That snap in board is the DSP module, and is responsible for CG filtering, AtoD conversion and many other jobs vital to the radios operation. Don't leave it out, and don't loose it!

Options, as in software options, are held in E2PROM memory in the form of a Feature Encryption Code. This code, along with a ROM serial number (unique to each unit) decode internally into a 'list' of features. The radio already has all the 'hardware' required to do everything, its just a matter of permitting - or inhibiting - use of each feature based on the list so generated.

 

[SCPD]

broken LPE200

Hey there, does anyone in Canada or the US know of a depot that would repair my radio at a fair price?


thanks