Magnavox Model 37MF231D/37 dead

[AlRad]

This TV is dead. After reading some of the technical material on this forum I measured all the pins on the IR/on-off board and there is no voltage present on any of the pins. My understanding is that there should be a %VDC standby voltage here that is used to initiate the other TV functions at turn-on.

I got this TV from my brother-in-law who said it just stopped working and he was going to throw it away. So I am using it as a learning opportunity and trying not to use it for target practice.

I inspected the p/s components and found nothing obvious; no burned parts, buldged caps, or broken components. The TV had been worked before by an unknow technician and the board shows where two cap were replaced (not factory soldering). I don't have a schematic and couldn't find the manual on toms-service-manuals listing. I found a 42MF231D_50MF231 but not similiar to mine.






The pictures are of the under side of the p/s with part number. One picture show 1200/35v and 2200/25v written on the chassis but I couldn't find a 1220ufd 35v cap on the board.

I would appreciate any help in repairing this TV.
Thanks, AlRad

[tom66]

Re: Magnavox Model 37MF231D/37 dead

Can you post a picture of your model # sticker this will have a chassis code like Q523.LA on it which is used for service manuals.

[AlRad]

Re: Magnavox Model 37MF231D/37 dead

Here is the picture of Model# sticker.

[tom66]

Re: Magnavox Model 37MF231D/37 dead

TPE1.0U-LA then.

[AlRad]

Re: Magnavox Model 37MF231D/37 dead

Thanks Tom66 for the info. i will update when i find anything. I didn't see a cap kit for this tv on the forum. Do you have info or source for the caps?

[aaronwt6]

Re: Magnavox Model 37MF231D/37 dead

http://www.ebay.com/itm/230677099638

I just did the swap out myself on one. I'd be skeptical if its the caps or not if you are getting absolutely no voltage on the standby pins. Mine would at least turn on for a bit til it got hot. Also, the light on the front should glow without powering up the TV.

[aaronwt6]

Re: Magnavox Model 37MF231D/37 dead

Here's a couple complete PS's on Ebay for around $30.

http://www.ebay.com/itm/Philips-mode...#ht_133wt_1399


http://www.ebay.com/itm/313815866811...7#ht_64wt_1161

[AlRad]

Re: Magnavox Model 37MF231D/37 dead

I've been trying to figure out the manual which contains info for 26", 32",37", and 42". It seems to apply mainly to the 26" with reference to other models. It does contain a 37" and 42" supplemental material for the P/S. Using the P/S info and probing the board I found that on the
1089 connector to the Main Board:
pin 1and 2, 16v is reading 11v
pin 3, 24A is 24v
pin 4, Bright adjust is 0.788v
pin 5, Inverter on-off is 0.003v
pin 9, standy is 0v
pin 6, 7, 8, and 10 are ground

connector 1088 to the Inverter Board:
pins 1-5, 24v is 0.158v
pin 6, Bright adjust is 0.787v
pin 8-12 are ground

The p/s 16v reading 11v and no 24Av on 1089 pin 3 and no standyby voltage would seem to be a p/s problem but I don't know the start up sequence of this unit. Looking at the schematics it appears that the Main Board supplies the standby voltage to the IR card and the p/s. I am still looking for the schematic for the "Main Board".

I don't mean to ramble, just trying to make sense of 128 pages of info and find the right clues.

Does this info indicate a definite p/s problem or do I need to supply more info? If bad p/s is the answer I will go to ebay as aaronwt6 suggested.
Thanks, AlRad